[PATCH v4 00/17] perf: KVM: Fix, optimize, and clean up callbacks

[PATCH v4 00/17] perf: KVM: Fix, optimize, and clean up callbacks

[Sean Christopherson]

This is a combination of ~2 series to fix bugs in the perf+KVM callbacks,
optimize the callbacks by employing static_call, and do a variety of
cleanup in both perf and KVM.

For the non-perf patches, I think everything except patch 13 (Paolo) and
patches 15 and 16 (Marc) has the appropriate acks.

Patch 1 fixes a set of mostly-theoretical bugs by protecting the guest
callbacks pointer with RCU.

Patches 2 and 3 fix an Intel PT handling bug where KVM incorrectly
eats PT interrupts when PT is supposed to be owned entirely by the host.

Patches 4-9 clean up perf's callback infrastructure and switch to
static_call for arm64 and x86 (the only survivors).

Patches 10-17 clean up related KVM code and unify the arm64/x86 callbacks.

Based on Linus' tree, commit cb690f5238d7 ("Merge tag 'for-5.16/drivers...).

v4:
  - Rebase.
  - Collect acks and reviews.
  - Fully protect perf_guest_cbs with RCU. [Paolo].
  - Add patch to hide arm64's kvm_arm_pmu_available behind
    CONFIG_HW_PERF_EVENTS=y.

v3:
  - https://lore.kernel.org/all/20210922000533.713300-1-seanjc@google.com/
  - Add wrappers for guest callbacks to that stubs can be provided when
    GUEST_PERF_EVENTS=n.
  - s/HAVE_GUEST_PERF_EVENTS/GUEST_PERF_EVENTS and select it from KVM
    and XEN_PV instead of from top-level arm64/x86. [Paolo]
  - Drop an unnecessary synchronize_rcu() when registering callbacks. [Peter]
  - Retain a WARN_ON_ONCE() when unregistering callbacks if the caller
    didn't provide the correct pointer. [Peter]
  - Rework the static_call patch to move it all to common perf.
  - Add a patch to drop the (un)register stubs, made possible after
    having KVM+XEN_PV select GUEST_PERF_EVENTS.
  - Split dropping guest callback "support" for arm, csky, etc... to a
    separate patch, to make introducing GUEST_PERF_EVENTS cleaner.
  
v2 (relative to static_call v10):
  - Split the patch into the semantic change (multiplexed ->state) and
    introduction of static_call.
  - Don't use '0' for "not a guest RIP".
  - Handle unregister path.
  - Drop changes for architectures that can be culled entirely.

v2 (relative to v1):
  - https://lkml.kernel.org/r/20210828003558.713983-6-seanjc@google.com
  - Drop per-cpu approach. [Peter]
  - Fix mostly-theoretical reload and use-after-free with READ_ONCE(),
    WRITE_ONCE(), and synchronize_rcu(). [Peter]
  - Avoid new exports like the plague. [Peter]

v1:
  - https://lkml.kernel.org/r/20210827005718.585190-1-seanjc@google.com

v10 static_call:
  - https://lkml.kernel.org/r/20210806133802.3528-2-lingshan.zhu@intel.com

Like Xu (1):
  perf/core: Rework guest callbacks to prepare for static_call support

Sean Christopherson (16):
  perf: Protect perf_guest_cbs with RCU
  KVM: x86: Register perf callbacks after calling vendor's
    hardware_setup()
  KVM: x86: Register Processor Trace interrupt hook iff PT enabled in
    guest
  perf: Stop pretending that perf can handle multiple guest callbacks
  perf: Drop dead and useless guest "support" from arm, csky, nds32 and
    riscv
  perf: Add wrappers for invoking guest callbacks
  perf: Force architectures to opt-in to guest callbacks
  perf/core: Use static_call to optimize perf_guest_info_callbacks
  KVM: x86: Drop current_vcpu for kvm_running_vcpu + kvm_arch_vcpu
    variable
  KVM: x86: More precisely identify NMI from guest when handling PMI
  KVM: Move x86's perf guest info callbacks to generic KVM
  KVM: x86: Move Intel Processor Trace interrupt handler to vmx.c
  KVM: arm64: Convert to the generic perf callbacks
  KVM: arm64: Hide kvm_arm_pmu_available behind CONFIG_HW_PERF_EVENTS=y
  KVM: arm64: Drop perf.c and fold its tiny bits of code into arm.c
  perf: Drop guest callback (un)register stubs

 arch/arm/kernel/perf_callchain.c   | 28 ++------------
 arch/arm64/include/asm/kvm_host.h  | 11 +++++-
 arch/arm64/kernel/image-vars.h     |  2 +
 arch/arm64/kernel/perf_callchain.c | 13 ++++---
 arch/arm64/kvm/Kconfig             |  1 +
 arch/arm64/kvm/Makefile            |  2 +-
 arch/arm64/kvm/arm.c               | 10 ++++-
 arch/arm64/kvm/perf.c              | 59 ------------------------------
 arch/arm64/kvm/pmu-emul.c          |  2 +
 arch/csky/kernel/perf_callchain.c  | 10 -----
 arch/nds32/kernel/perf_event_cpu.c | 29 ++-------------
 arch/riscv/kernel/perf_callchain.c | 10 -----
 arch/x86/events/core.c             | 13 ++++---
 arch/x86/events/intel/core.c       |  5 +--
 arch/x86/include/asm/kvm_host.h    |  7 +++-
 arch/x86/kvm/Kconfig               |  1 +
 arch/x86/kvm/pmu.c                 |  2 +-
 arch/x86/kvm/svm/svm.c             |  2 +-
 arch/x86/kvm/vmx/vmx.c             | 25 ++++++++++++-
 arch/x86/kvm/x86.c                 | 58 +++++------------------------
 arch/x86/kvm/x86.h                 | 17 +++++++--
 arch/x86/xen/Kconfig               |  1 +
 arch/x86/xen/pmu.c                 | 32 +++++++---------
 include/kvm/arm_pmu.h              | 19 ++++++----
 include/linux/kvm_host.h           | 10 +++++
 include/linux/perf_event.h         | 44 ++++++++++++++++------
 init/Kconfig                       |  4 ++
 kernel/events/core.c               | 41 +++++++++++++++------
 virt/kvm/kvm_main.c                | 44 ++++++++++++++++++++++
 29 files changed, 246 insertions(+), 256 deletions(-)
 delete mode 100644 arch/arm64/kvm/perf.c

-- 
2.34.0.rc0.344.g81b53c2807-goog

[PATCH v4 01/17] perf: Protect perf_guest_cbs with RCU

[Sean Christopherson]

Protect perf_guest_cbs with RCU to fix multiple possible errors.  Luckily,
all paths that read perf_guest_cbs already require RCU protection, e.g. to
protect the callback chains, so only the direct perf_guest_cbs touchpoints
need to be modified.

Bug #1 is a simple lack of WRITE_ONCE/READ_ONCE behavior to ensure
perf_guest_cbs isn't reloaded between a !NULL check and a dereference.
Fixed via the READ_ONCE() in rcu_dereference().

Bug #2 is that on weakly-ordered architectures, updates to the callbacks
themselves are not guaranteed to be visible before the pointer is made
visible to readers.  Fixed by the smp_store_release() in
rcu_assign_pointer() when the new pointer is non-NULL.

Bug #3 is that, because the callbacks are global, it's possible for
readers to run in parallel with an unregisters, and thus a module
implementing the callbacks can be unloaded while readers are in flight,
resulting in a use-after-free.  Fixed by a synchronize_rcu() call when
unregistering callbacks.

Bug #1 escaped notice because it's extremely unlikely a compiler will
reload perf_guest_cbs in this sequence.  perf_guest_cbs does get reloaded
for future derefs, e.g. for ->is_user_mode(), but the ->is_in_guest()
guard all but guarantees the consumer will win the race, e.g. to nullify
perf_guest_cbs, KVM has to completely exit the guest and teardown down
all VMs before KVM start its module unload / unregister sequence.  This
also makes it all but impossible to encounter bug #3.

Bug #2 has not been a problem because all architectures that register
callbacks are strongly ordered and/or have a static set of callbacks.

But with help, unloading kvm_intel can trigger bug #1 e.g. wrapping
perf_guest_cbs with READ_ONCE in perf_misc_flags() while spamming
kvm_intel module load/unload leads to:

  BUG: kernel NULL pointer dereference, address: 0000000000000000
  #PF: supervisor read access in kernel mode
  #PF: error_code(0x0000) - not-present page
  PGD 0 P4D 0
  Oops: 0000 [#1] PREEMPT SMP
  CPU: 6 PID: 1825 Comm: stress Not tainted 5.14.0-rc2+ #459
  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
  RIP: 0010:perf_misc_flags+0x1c/0x70
  Call Trace:
   perf_prepare_sample+0x53/0x6b0
   perf_event_output_forward+0x67/0x160
   __perf_event_overflow+0x52/0xf0
   handle_pmi_common+0x207/0x300
   intel_pmu_handle_irq+0xcf/0x410
   perf_event_nmi_handler+0x28/0x50
   nmi_handle+0xc7/0x260
   default_do_nmi+0x6b/0x170
   exc_nmi+0x103/0x130
   asm_exc_nmi+0x76/0xbf

Fixes: 39447b386c84 ("perf: Enhance perf to allow for guest statistic collection from host")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/arm/kernel/perf_callchain.c   | 17 +++++++++++------
 arch/arm64/kernel/perf_callchain.c | 18 ++++++++++++------
 arch/csky/kernel/perf_callchain.c  |  6 ++++--
 arch/nds32/kernel/perf_event_cpu.c | 17 +++++++++++------
 arch/riscv/kernel/perf_callchain.c |  7 +++++--
 arch/x86/events/core.c             | 17 +++++++++++------
 arch/x86/events/intel/core.c       |  9 ++++++---
 include/linux/perf_event.h         | 13 ++++++++++++-
 kernel/events/core.c               | 13 ++++++++++---
 9 files changed, 82 insertions(+), 35 deletions(-)

diff --git a/arch/arm/kernel/perf_callchain.c b/arch/arm/kernel/perf_callchain.c
index 3b69a76d341e..1626dfc6f6ce 100644
--- a/arch/arm/kernel/perf_callchain.c
+++ b/arch/arm/kernel/perf_callchain.c
@@ -62,9 +62,10 @@ user_backtrace(struct frame_tail __user *tail,
 void
 perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
 {
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	struct frame_tail __user *tail;
 
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
+	if (guest_cbs && guest_cbs->is_in_guest()) {
 		/* We don't support guest os callchain now */
 		return;
 	}
@@ -98,9 +99,10 @@ callchain_trace(struct stackframe *fr,
 void
 perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
 {
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	struct stackframe fr;
 
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
+	if (guest_cbs && guest_cbs->is_in_guest()) {
 		/* We don't support guest os callchain now */
 		return;
 	}
@@ -111,18 +113,21 @@ perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *re
 
 unsigned long perf_instruction_pointer(struct pt_regs *regs)
 {
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest())
-		return perf_guest_cbs->get_guest_ip();
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
+
+	if (guest_cbs && guest_cbs->is_in_guest())
+		return guest_cbs->get_guest_ip();
 
 	return instruction_pointer(regs);
 }
 
 unsigned long perf_misc_flags(struct pt_regs *regs)
 {
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	int misc = 0;
 
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
-		if (perf_guest_cbs->is_user_mode())
+	if (guest_cbs && guest_cbs->is_in_guest()) {
+		if (guest_cbs->is_user_mode())
 			misc |= PERF_RECORD_MISC_GUEST_USER;
 		else
 			misc |= PERF_RECORD_MISC_GUEST_KERNEL;
diff --git a/arch/arm64/kernel/perf_callchain.c b/arch/arm64/kernel/perf_callchain.c
index 4a72c2727309..86d9f2013172 100644
--- a/arch/arm64/kernel/perf_callchain.c
+++ b/arch/arm64/kernel/perf_callchain.c
@@ -102,7 +102,9 @@ compat_user_backtrace(struct compat_frame_tail __user *tail,
 void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
 			 struct pt_regs *regs)
 {
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
+
+	if (guest_cbs && guest_cbs->is_in_guest()) {
 		/* We don't support guest os callchain now */
 		return;
 	}
@@ -147,9 +149,10 @@ static bool callchain_trace(void *data, unsigned long pc)
 void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
 			   struct pt_regs *regs)
 {
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	struct stackframe frame;
 
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
+	if (guest_cbs && guest_cbs->is_in_guest()) {
 		/* We don't support guest os callchain now */
 		return;
 	}
@@ -160,18 +163,21 @@ void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
 
 unsigned long perf_instruction_pointer(struct pt_regs *regs)
 {
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest())
-		return perf_guest_cbs->get_guest_ip();
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
+
+	if (guest_cbs && guest_cbs->is_in_guest())
+		return guest_cbs->get_guest_ip();
 
 	return instruction_pointer(regs);
 }
 
 unsigned long perf_misc_flags(struct pt_regs *regs)
 {
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	int misc = 0;
 
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
-		if (perf_guest_cbs->is_user_mode())
+	if (guest_cbs && guest_cbs->is_in_guest()) {
+		if (guest_cbs->is_user_mode())
 			misc |= PERF_RECORD_MISC_GUEST_USER;
 		else
 			misc |= PERF_RECORD_MISC_GUEST_KERNEL;
diff --git a/arch/csky/kernel/perf_callchain.c b/arch/csky/kernel/perf_callchain.c
index ab55e98ee8f6..35318a635a5f 100644
--- a/arch/csky/kernel/perf_callchain.c
+++ b/arch/csky/kernel/perf_callchain.c
@@ -86,10 +86,11 @@ static unsigned long user_backtrace(struct perf_callchain_entry_ctx *entry,
 void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
 			 struct pt_regs *regs)
 {
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	unsigned long fp = 0;
 
 	/* C-SKY does not support virtualization. */
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest())
+	if (guest_cbs && guest_cbs->is_in_guest())
 		return;
 
 	fp = regs->regs[4];
@@ -110,10 +111,11 @@ void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
 void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
 			   struct pt_regs *regs)
 {
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	struct stackframe fr;
 
 	/* C-SKY does not support virtualization. */
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
+	if (guest_cbs && guest_cbs->is_in_guest()) {
 		pr_warn("C-SKY does not support perf in guest mode!");
 		return;
 	}
diff --git a/arch/nds32/kernel/perf_event_cpu.c b/arch/nds32/kernel/perf_event_cpu.c
index 0ce6f9f307e6..f38791960781 100644
--- a/arch/nds32/kernel/perf_event_cpu.c
+++ b/arch/nds32/kernel/perf_event_cpu.c
@@ -1363,6 +1363,7 @@ void
 perf_callchain_user(struct perf_callchain_entry_ctx *entry,
 		    struct pt_regs *regs)
 {
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	unsigned long fp = 0;
 	unsigned long gp = 0;
 	unsigned long lp = 0;
@@ -1371,7 +1372,7 @@ perf_callchain_user(struct perf_callchain_entry_ctx *entry,
 
 	leaf_fp = 0;
 
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
+	if (guest_cbs && guest_cbs->is_in_guest()) {
 		/* We don't support guest os callchain now */
 		return;
 	}
@@ -1479,9 +1480,10 @@ void
 perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
 		      struct pt_regs *regs)
 {
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	struct stackframe fr;
 
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
+	if (guest_cbs && guest_cbs->is_in_guest()) {
 		/* We don't support guest os callchain now */
 		return;
 	}
@@ -1493,20 +1495,23 @@ perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
 
 unsigned long perf_instruction_pointer(struct pt_regs *regs)
 {
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
+
 	/* However, NDS32 does not support virtualization */
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest())
-		return perf_guest_cbs->get_guest_ip();
+	if (guest_cbs && guest_cbs->is_in_guest())
+		return guest_cbs->get_guest_ip();
 
 	return instruction_pointer(regs);
 }
 
 unsigned long perf_misc_flags(struct pt_regs *regs)
 {
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	int misc = 0;
 
 	/* However, NDS32 does not support virtualization */
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
-		if (perf_guest_cbs->is_user_mode())
+	if (guest_cbs && guest_cbs->is_in_guest()) {
+		if (guest_cbs->is_user_mode())
 			misc |= PERF_RECORD_MISC_GUEST_USER;
 		else
 			misc |= PERF_RECORD_MISC_GUEST_KERNEL;
diff --git a/arch/riscv/kernel/perf_callchain.c b/arch/riscv/kernel/perf_callchain.c
index 0bb1854dce83..8ecfc4c128bc 100644
--- a/arch/riscv/kernel/perf_callchain.c
+++ b/arch/riscv/kernel/perf_callchain.c
@@ -56,10 +56,11 @@ static unsigned long user_backtrace(struct perf_callchain_entry_ctx *entry,
 void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
 			 struct pt_regs *regs)
 {
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	unsigned long fp = 0;
 
 	/* RISC-V does not support perf in guest mode. */
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest())
+	if (guest_cbs && guest_cbs->is_in_guest())
 		return;
 
 	fp = regs->s0;
@@ -78,8 +79,10 @@ static bool fill_callchain(void *entry, unsigned long pc)
 void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
 			   struct pt_regs *regs)
 {
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
+
 	/* RISC-V does not support perf in guest mode. */
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
+	if (guest_cbs && guest_cbs->is_in_guest()) {
 		pr_warn("RISC-V does not support perf in guest mode!");
 		return;
 	}
diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 38b2c779146f..32cec290d3ad 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -2768,10 +2768,11 @@ static bool perf_hw_regs(struct pt_regs *regs)
 void
 perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
 {
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	struct unwind_state state;
 	unsigned long addr;
 
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
+	if (guest_cbs && guest_cbs->is_in_guest()) {
 		/* TODO: We don't support guest os callchain now */
 		return;
 	}
@@ -2871,10 +2872,11 @@ perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry_ctx *ent
 void
 perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
 {
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	struct stack_frame frame;
 	const struct stack_frame __user *fp;
 
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
+	if (guest_cbs && guest_cbs->is_in_guest()) {
 		/* TODO: We don't support guest os callchain now */
 		return;
 	}
@@ -2951,18 +2953,21 @@ static unsigned long code_segment_base(struct pt_regs *regs)
 
 unsigned long perf_instruction_pointer(struct pt_regs *regs)
 {
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest())
-		return perf_guest_cbs->get_guest_ip();
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
+
+	if (guest_cbs && guest_cbs->is_in_guest())
+		return guest_cbs->get_guest_ip();
 
 	return regs->ip + code_segment_base(regs);
 }
 
 unsigned long perf_misc_flags(struct pt_regs *regs)
 {
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	int misc = 0;
 
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
-		if (perf_guest_cbs->is_user_mode())
+	if (guest_cbs && guest_cbs->is_in_guest()) {
+		if (guest_cbs->is_user_mode())
 			misc |= PERF_RECORD_MISC_GUEST_USER;
 		else
 			misc |= PERF_RECORD_MISC_GUEST_KERNEL;
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 603964408d2d..cde29bd5bb53 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -2837,6 +2837,7 @@ static int handle_pmi_common(struct pt_regs *regs, u64 status)
 {
 	struct perf_sample_data data;
 	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
+	struct perf_guest_info_callbacks *guest_cbs;
 	int bit;
 	int handled = 0;
 	u64 intel_ctrl = hybrid(cpuc->pmu, intel_ctrl);
@@ -2903,9 +2904,11 @@ static int handle_pmi_common(struct pt_regs *regs, u64 status)
 	 */
 	if (__test_and_clear_bit(GLOBAL_STATUS_TRACE_TOPAPMI_BIT, (unsigned long *)&status)) {
 		handled++;
-		if (unlikely(perf_guest_cbs && perf_guest_cbs->is_in_guest() &&
-			perf_guest_cbs->handle_intel_pt_intr))
-			perf_guest_cbs->handle_intel_pt_intr();
+
+		guest_cbs = perf_get_guest_cbs();
+		if (unlikely(guest_cbs && guest_cbs->is_in_guest() &&
+			     guest_cbs->handle_intel_pt_intr))
+			guest_cbs->handle_intel_pt_intr();
 		else
 			intel_pt_interrupt();
 	}
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 0dcfd265beed..318c489b735b 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1240,7 +1240,18 @@ extern void perf_event_bpf_event(struct bpf_prog *prog,
 				 enum perf_bpf_event_type type,
 				 u16 flags);
 
-extern struct perf_guest_info_callbacks *perf_guest_cbs;
+extern struct perf_guest_info_callbacks __rcu *perf_guest_cbs;
+static inline struct perf_guest_info_callbacks *perf_get_guest_cbs(void)
+{
+	/*
+	 * Callbacks are RCU-protected and must be READ_ONCE to avoid reloading
+	 * the callbacks between a !NULL check and dereferences, to ensure
+	 * pending stores/changes to the callback pointers are visible before a
+	 * non-NULL perf_guest_cbs is visible to readers, and to prevent a
+	 * module from unloading callbacks while readers are active.
+	 */
+	return rcu_dereference(perf_guest_cbs);
+}
 extern int perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *callbacks);
 extern int perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *callbacks);
 
diff --git a/kernel/events/core.c b/kernel/events/core.c
index f2253ea729a2..0cc775f702f8 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6526,18 +6526,25 @@ static void perf_pending_event(struct irq_work *entry)
  * Later on, we might change it to a list if there is
  * another virtualization implementation supporting the callbacks.
  */
-struct perf_guest_info_callbacks *perf_guest_cbs;
+struct perf_guest_info_callbacks __rcu *perf_guest_cbs;
 
 int perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
 {
-	perf_guest_cbs = cbs;
+	if (WARN_ON_ONCE(rcu_access_pointer(perf_guest_cbs)))
+		return -EBUSY;
+
+	rcu_assign_pointer(perf_guest_cbs, cbs);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(perf_register_guest_info_callbacks);
 
 int perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
 {
-	perf_guest_cbs = NULL;
+	if (WARN_ON_ONCE(rcu_access_pointer(perf_guest_cbs) != cbs))
+		return -EINVAL;
+
+	rcu_assign_pointer(perf_guest_cbs, NULL);
+	synchronize_rcu();
 	return 0;
 }
 EXPORT_SYMBOL_GPL(perf_unregister_guest_info_callbacks);
-- 
2.34.0.rc0.344.g81b53c2807-goog

Re: [PATCH v4 01/17] perf: Protect perf_guest_cbs with RCU

[Paolo Bonzini]

On 11/11/21 03:07, Sean Christopherson wrote:
> Protect perf_guest_cbs with RCU to fix multiple possible errors.  Luckily,
> all paths that read perf_guest_cbs already require RCU protection, e.g. to
> protect the callback chains, so only the direct perf_guest_cbs touchpoints
> need to be modified.
> 
> Bug #1 is a simple lack of WRITE_ONCE/READ_ONCE behavior to ensure
> perf_guest_cbs isn't reloaded between a !NULL check and a dereference.
> Fixed via the READ_ONCE() in rcu_dereference().
> 
> Bug #2 is that on weakly-ordered architectures, updates to the callbacks
> themselves are not guaranteed to be visible before the pointer is made
> visible to readers.  Fixed by the smp_store_release() in
> rcu_assign_pointer() when the new pointer is non-NULL.
> 
> Bug #3 is that, because the callbacks are global, it's possible for
> readers to run in parallel with an unregisters, and thus a module
> implementing the callbacks can be unloaded while readers are in flight,
> resulting in a use-after-free.  Fixed by a synchronize_rcu() call when
> unregistering callbacks.
> 
> Bug #1 escaped notice because it's extremely unlikely a compiler will
> reload perf_guest_cbs in this sequence.  perf_guest_cbs does get reloaded
> for future derefs, e.g. for ->is_user_mode(), but the ->is_in_guest()
> guard all but guarantees the consumer will win the race, e.g. to nullify
> perf_guest_cbs, KVM has to completely exit the guest and teardown down
> all VMs before KVM start its module unload / unregister sequence.  This
> also makes it all but impossible to encounter bug #3.
> 
> Bug #2 has not been a problem because all architectures that register
> callbacks are strongly ordered and/or have a static set of callbacks.
> 
> But with help, unloading kvm_intel can trigger bug #1 e.g. wrapping
> perf_guest_cbs with READ_ONCE in perf_misc_flags() while spamming
> kvm_intel module load/unload leads to:
> 
>    BUG: kernel NULL pointer dereference, address: 0000000000000000
>    #PF: supervisor read access in kernel mode
>    #PF: error_code(0x0000) - not-present page
>    PGD 0 P4D 0
>    Oops: 0000 [#1] PREEMPT SMP
>    CPU: 6 PID: 1825 Comm: stress Not tainted 5.14.0-rc2+ #459
>    Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
>    RIP: 0010:perf_misc_flags+0x1c/0x70
>    Call Trace:
>     perf_prepare_sample+0x53/0x6b0
>     perf_event_output_forward+0x67/0x160
>     __perf_event_overflow+0x52/0xf0
>     handle_pmi_common+0x207/0x300
>     intel_pmu_handle_irq+0xcf/0x410
>     perf_event_nmi_handler+0x28/0x50
>     nmi_handle+0xc7/0x260
>     default_do_nmi+0x6b/0x170
>     exc_nmi+0x103/0x130
>     asm_exc_nmi+0x76/0xbf
> 
> Fixes: 39447b386c84 ("perf: Enhance perf to allow for guest statistic collection from host")
> Cc: stable@vger.kernel.org
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>

One nit:

>   EXPORT_SYMBOL_GPL(perf_register_guest_info_callbacks);
>   
>   int perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
>   {
> -	perf_guest_cbs = NULL;
> +	if (WARN_ON_ONCE(rcu_access_pointer(perf_guest_cbs) != cbs))
> +		return -EINVAL;
> +
> +	rcu_assign_pointer(perf_guest_cbs, NULL);
> +	synchronize_rcu();
This technically could be RCU_INIT_POINTER but it's not worth a respin.
There are dozens of other occurrences, and if somebody wanted they
could use Coccinelle to fix all of them.

Paolo

Re: [PATCH v4 01/17] perf: Protect perf_guest_cbs with RCU

[Peter Zijlstra]

On Thu, Nov 11, 2021 at 08:26:58AM +0100, Paolo Bonzini wrote:
> On 11/11/21 03:07, Sean Christopherson wrote:

> >   EXPORT_SYMBOL_GPL(perf_register_guest_info_callbacks);
> >   int perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
> >   {
> > -	perf_guest_cbs = NULL;
> > +	if (WARN_ON_ONCE(rcu_access_pointer(perf_guest_cbs) != cbs))
> > +		return -EINVAL;
> > +
> > +	rcu_assign_pointer(perf_guest_cbs, NULL);
> > +	synchronize_rcu();
> This technically could be RCU_INIT_POINTER but it's not worth a respin.
> There are dozens of other occurrences, and if somebody wanted they
> could use Coccinelle to fix all of them.

I've been pushing the other way, trying to get rid of RCU_INIT_POINTER()
since rcu_assign_pointer(, NULL) actualy DTRT per __builtin_constant_p()
etc.

There's a very few sites where we use RCU_INIT_POINTER() with a !NULL
argument, and those are 'special'.

Re: [PATCH v4 01/17] perf: Protect perf_guest_cbs with RCU

[Paolo Bonzini]

On 11/11/21 11:47, Peter Zijlstra wrote:
>> This technically could be RCU_INIT_POINTER but it's not worth a respin.
>> There are dozens of other occurrences, and if somebody wanted they
>> could use Coccinelle to fix all of them.
> I've been pushing the other way, trying to get rid of RCU_INIT_POINTER()
> since rcu_assign_pointer(, NULL) actualy DTRT per __builtin_constant_p()
> etc.

Oh, that's pretty cool to know, thanks!

Paolo

> There's a very few sites where we use RCU_INIT_POINTER() with a !NULL
> argument, and those are 'special'.
> 

[tip: perf/core] perf: Protect perf_guest_cbs with RCU

[tip-bot2 for Sean Christopherson]

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     ff083a2d972f56bebfd82409ca62e5dfce950961
Gitweb:        https://git.kernel.org/tip/ff083a2d972f56bebfd82409ca62e5dfce950961
Author:        Sean Christopherson <seanjc@google.com>
AuthorDate:    Thu, 11 Nov 2021 02:07:22 
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Wed, 17 Nov 2021 14:49:06 +01:00

perf: Protect perf_guest_cbs with RCU

Protect perf_guest_cbs with RCU to fix multiple possible errors.  Luckily,
all paths that read perf_guest_cbs already require RCU protection, e.g. to
protect the callback chains, so only the direct perf_guest_cbs touchpoints
need to be modified.

Bug #1 is a simple lack of WRITE_ONCE/READ_ONCE behavior to ensure
perf_guest_cbs isn't reloaded between a !NULL check and a dereference.
Fixed via the READ_ONCE() in rcu_dereference().

Bug #2 is that on weakly-ordered architectures, updates to the callbacks
themselves are not guaranteed to be visible before the pointer is made
visible to readers.  Fixed by the smp_store_release() in
rcu_assign_pointer() when the new pointer is non-NULL.

Bug #3 is that, because the callbacks are global, it's possible for
readers to run in parallel with an unregisters, and thus a module
implementing the callbacks can be unloaded while readers are in flight,
resulting in a use-after-free.  Fixed by a synchronize_rcu() call when
unregistering callbacks.

Bug #1 escaped notice because it's extremely unlikely a compiler will
reload perf_guest_cbs in this sequence.  perf_guest_cbs does get reloaded
for future derefs, e.g. for ->is_user_mode(), but the ->is_in_guest()
guard all but guarantees the consumer will win the race, e.g. to nullify
perf_guest_cbs, KVM has to completely exit the guest and teardown down
all VMs before KVM start its module unload / unregister sequence.  This
also makes it all but impossible to encounter bug #3.

Bug #2 has not been a problem because all architectures that register
callbacks are strongly ordered and/or have a static set of callbacks.

But with help, unloading kvm_intel can trigger bug #1 e.g. wrapping
perf_guest_cbs with READ_ONCE in perf_misc_flags() while spamming
kvm_intel module load/unload leads to:

  BUG: kernel NULL pointer dereference, address: 0000000000000000
  #PF: supervisor read access in kernel mode
  #PF: error_code(0x0000) - not-present page
  PGD 0 P4D 0
  Oops: 0000 [#1] PREEMPT SMP
  CPU: 6 PID: 1825 Comm: stress Not tainted 5.14.0-rc2+ #459
  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
  RIP: 0010:perf_misc_flags+0x1c/0x70
  Call Trace:
   perf_prepare_sample+0x53/0x6b0
   perf_event_output_forward+0x67/0x160
   __perf_event_overflow+0x52/0xf0
   handle_pmi_common+0x207/0x300
   intel_pmu_handle_irq+0xcf/0x410
   perf_event_nmi_handler+0x28/0x50
   nmi_handle+0xc7/0x260
   default_do_nmi+0x6b/0x170
   exc_nmi+0x103/0x130
   asm_exc_nmi+0x76/0xbf

Fixes: 39447b386c84 ("perf: Enhance perf to allow for guest statistic collection from host")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20211111020738.2512932-2-seanjc@google.com
---
 arch/arm/kernel/perf_callchain.c   | 17 +++++++++++------
 arch/arm64/kernel/perf_callchain.c | 18 ++++++++++++------
 arch/csky/kernel/perf_callchain.c  |  6 ++++--
 arch/nds32/kernel/perf_event_cpu.c | 17 +++++++++++------
 arch/riscv/kernel/perf_callchain.c |  7 +++++--
 arch/x86/events/core.c             | 17 +++++++++++------
 arch/x86/events/intel/core.c       |  9 ++++++---
 include/linux/perf_event.h         | 13 ++++++++++++-
 kernel/events/core.c               | 13 ++++++++++---
 9 files changed, 82 insertions(+), 35 deletions(-)

diff --git a/arch/arm/kernel/perf_callchain.c b/arch/arm/kernel/perf_callchain.c
index 3b69a76..1626dfc 100644
--- a/arch/arm/kernel/perf_callchain.c
+++ b/arch/arm/kernel/perf_callchain.c
@@ -62,9 +62,10 @@ user_backtrace(struct frame_tail __user *tail,
 void
 perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
 {
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	struct frame_tail __user *tail;
 
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
+	if (guest_cbs && guest_cbs->is_in_guest()) {
 		/* We don't support guest os callchain now */
 		return;
 	}
@@ -98,9 +99,10 @@ callchain_trace(struct stackframe *fr,
 void
 perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
 {
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	struct stackframe fr;
 
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
+	if (guest_cbs && guest_cbs->is_in_guest()) {
 		/* We don't support guest os callchain now */
 		return;
 	}
@@ -111,18 +113,21 @@ perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *re
 
 unsigned long perf_instruction_pointer(struct pt_regs *regs)
 {
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest())
-		return perf_guest_cbs->get_guest_ip();
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
+
+	if (guest_cbs && guest_cbs->is_in_guest())
+		return guest_cbs->get_guest_ip();
 
 	return instruction_pointer(regs);
 }
 
 unsigned long perf_misc_flags(struct pt_regs *regs)
 {
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	int misc = 0;
 
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
-		if (perf_guest_cbs->is_user_mode())
+	if (guest_cbs && guest_cbs->is_in_guest()) {
+		if (guest_cbs->is_user_mode())
 			misc |= PERF_RECORD_MISC_GUEST_USER;
 		else
 			misc |= PERF_RECORD_MISC_GUEST_KERNEL;
diff --git a/arch/arm64/kernel/perf_callchain.c b/arch/arm64/kernel/perf_callchain.c
index 4a72c27..86d9f20 100644
--- a/arch/arm64/kernel/perf_callchain.c
+++ b/arch/arm64/kernel/perf_callchain.c
@@ -102,7 +102,9 @@ compat_user_backtrace(struct compat_frame_tail __user *tail,
 void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
 			 struct pt_regs *regs)
 {
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
+
+	if (guest_cbs && guest_cbs->is_in_guest()) {
 		/* We don't support guest os callchain now */
 		return;
 	}
@@ -147,9 +149,10 @@ static bool callchain_trace(void *data, unsigned long pc)
 void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
 			   struct pt_regs *regs)
 {
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	struct stackframe frame;
 
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
+	if (guest_cbs && guest_cbs->is_in_guest()) {
 		/* We don't support guest os callchain now */
 		return;
 	}
@@ -160,18 +163,21 @@ void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
 
 unsigned long perf_instruction_pointer(struct pt_regs *regs)
 {
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest())
-		return perf_guest_cbs->get_guest_ip();
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
+
+	if (guest_cbs && guest_cbs->is_in_guest())
+		return guest_cbs->get_guest_ip();
 
 	return instruction_pointer(regs);
 }
 
 unsigned long perf_misc_flags(struct pt_regs *regs)
 {
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	int misc = 0;
 
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
-		if (perf_guest_cbs->is_user_mode())
+	if (guest_cbs && guest_cbs->is_in_guest()) {
+		if (guest_cbs->is_user_mode())
 			misc |= PERF_RECORD_MISC_GUEST_USER;
 		else
 			misc |= PERF_RECORD_MISC_GUEST_KERNEL;
diff --git a/arch/csky/kernel/perf_callchain.c b/arch/csky/kernel/perf_callchain.c
index ab55e98..35318a6 100644
--- a/arch/csky/kernel/perf_callchain.c
+++ b/arch/csky/kernel/perf_callchain.c
@@ -86,10 +86,11 @@ static unsigned long user_backtrace(struct perf_callchain_entry_ctx *entry,
 void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
 			 struct pt_regs *regs)
 {
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	unsigned long fp = 0;
 
 	/* C-SKY does not support virtualization. */
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest())
+	if (guest_cbs && guest_cbs->is_in_guest())
 		return;
 
 	fp = regs->regs[4];
@@ -110,10 +111,11 @@ void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
 void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
 			   struct pt_regs *regs)
 {
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	struct stackframe fr;
 
 	/* C-SKY does not support virtualization. */
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
+	if (guest_cbs && guest_cbs->is_in_guest()) {
 		pr_warn("C-SKY does not support perf in guest mode!");
 		return;
 	}
diff --git a/arch/nds32/kernel/perf_event_cpu.c b/arch/nds32/kernel/perf_event_cpu.c
index 0ce6f9f..f387919 100644
--- a/arch/nds32/kernel/perf_event_cpu.c
+++ b/arch/nds32/kernel/perf_event_cpu.c
@@ -1363,6 +1363,7 @@ void
 perf_callchain_user(struct perf_callchain_entry_ctx *entry,
 		    struct pt_regs *regs)
 {
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	unsigned long fp = 0;
 	unsigned long gp = 0;
 	unsigned long lp = 0;
@@ -1371,7 +1372,7 @@ perf_callchain_user(struct perf_callchain_entry_ctx *entry,
 
 	leaf_fp = 0;
 
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
+	if (guest_cbs && guest_cbs->is_in_guest()) {
 		/* We don't support guest os callchain now */
 		return;
 	}
@@ -1479,9 +1480,10 @@ void
 perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
 		      struct pt_regs *regs)
 {
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	struct stackframe fr;
 
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
+	if (guest_cbs && guest_cbs->is_in_guest()) {
 		/* We don't support guest os callchain now */
 		return;
 	}
@@ -1493,20 +1495,23 @@ perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
 
 unsigned long perf_instruction_pointer(struct pt_regs *regs)
 {
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
+
 	/* However, NDS32 does not support virtualization */
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest())
-		return perf_guest_cbs->get_guest_ip();
+	if (guest_cbs && guest_cbs->is_in_guest())
+		return guest_cbs->get_guest_ip();
 
 	return instruction_pointer(regs);
 }
 
 unsigned long perf_misc_flags(struct pt_regs *regs)
 {
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	int misc = 0;
 
 	/* However, NDS32 does not support virtualization */
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
-		if (perf_guest_cbs->is_user_mode())
+	if (guest_cbs && guest_cbs->is_in_guest()) {
+		if (guest_cbs->is_user_mode())
 			misc |= PERF_RECORD_MISC_GUEST_USER;
 		else
 			misc |= PERF_RECORD_MISC_GUEST_KERNEL;
diff --git a/arch/riscv/kernel/perf_callchain.c b/arch/riscv/kernel/perf_callchain.c
index 0bb1854..8ecfc4c 100644
--- a/arch/riscv/kernel/perf_callchain.c
+++ b/arch/riscv/kernel/perf_callchain.c
@@ -56,10 +56,11 @@ static unsigned long user_backtrace(struct perf_callchain_entry_ctx *entry,
 void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
 			 struct pt_regs *regs)
 {
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	unsigned long fp = 0;
 
 	/* RISC-V does not support perf in guest mode. */
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest())
+	if (guest_cbs && guest_cbs->is_in_guest())
 		return;
 
 	fp = regs->s0;
@@ -78,8 +79,10 @@ static bool fill_callchain(void *entry, unsigned long pc)
 void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
 			   struct pt_regs *regs)
 {
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
+
 	/* RISC-V does not support perf in guest mode. */
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
+	if (guest_cbs && guest_cbs->is_in_guest()) {
 		pr_warn("RISC-V does not support perf in guest mode!");
 		return;
 	}
diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 38b2c77..32cec29 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -2768,10 +2768,11 @@ static bool perf_hw_regs(struct pt_regs *regs)
 void
 perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
 {
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	struct unwind_state state;
 	unsigned long addr;
 
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
+	if (guest_cbs && guest_cbs->is_in_guest()) {
 		/* TODO: We don't support guest os callchain now */
 		return;
 	}
@@ -2871,10 +2872,11 @@ perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry_ctx *ent
 void
 perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
 {
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	struct stack_frame frame;
 	const struct stack_frame __user *fp;
 
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
+	if (guest_cbs && guest_cbs->is_in_guest()) {
 		/* TODO: We don't support guest os callchain now */
 		return;
 	}
@@ -2951,18 +2953,21 @@ static unsigned long code_segment_base(struct pt_regs *regs)
 
 unsigned long perf_instruction_pointer(struct pt_regs *regs)
 {
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest())
-		return perf_guest_cbs->get_guest_ip();
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
+
+	if (guest_cbs && guest_cbs->is_in_guest())
+		return guest_cbs->get_guest_ip();
 
 	return regs->ip + code_segment_base(regs);
 }
 
 unsigned long perf_misc_flags(struct pt_regs *regs)
 {
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	int misc = 0;
 
-	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
-		if (perf_guest_cbs->is_user_mode())
+	if (guest_cbs && guest_cbs->is_in_guest()) {
+		if (guest_cbs->is_user_mode())
 			misc |= PERF_RECORD_MISC_GUEST_USER;
 		else
 			misc |= PERF_RECORD_MISC_GUEST_KERNEL;
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 42cf01e..2258e02 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -2837,6 +2837,7 @@ static int handle_pmi_common(struct pt_regs *regs, u64 status)
 {
 	struct perf_sample_data data;
 	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
+	struct perf_guest_info_callbacks *guest_cbs;
 	int bit;
 	int handled = 0;
 	u64 intel_ctrl = hybrid(cpuc->pmu, intel_ctrl);
@@ -2903,9 +2904,11 @@ static int handle_pmi_common(struct pt_regs *regs, u64 status)
 	 */
 	if (__test_and_clear_bit(GLOBAL_STATUS_TRACE_TOPAPMI_BIT, (unsigned long *)&status)) {
 		handled++;
-		if (unlikely(perf_guest_cbs && perf_guest_cbs->is_in_guest() &&
-			perf_guest_cbs->handle_intel_pt_intr))
-			perf_guest_cbs->handle_intel_pt_intr();
+
+		guest_cbs = perf_get_guest_cbs();
+		if (unlikely(guest_cbs && guest_cbs->is_in_guest() &&
+			     guest_cbs->handle_intel_pt_intr))
+			guest_cbs->handle_intel_pt_intr();
 		else
 			intel_pt_interrupt();
 	}
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 0dcfd26..318c489 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1240,7 +1240,18 @@ extern void perf_event_bpf_event(struct bpf_prog *prog,
 				 enum perf_bpf_event_type type,
 				 u16 flags);
 
-extern struct perf_guest_info_callbacks *perf_guest_cbs;
+extern struct perf_guest_info_callbacks __rcu *perf_guest_cbs;
+static inline struct perf_guest_info_callbacks *perf_get_guest_cbs(void)
+{
+	/*
+	 * Callbacks are RCU-protected and must be READ_ONCE to avoid reloading
+	 * the callbacks between a !NULL check and dereferences, to ensure
+	 * pending stores/changes to the callback pointers are visible before a
+	 * non-NULL perf_guest_cbs is visible to readers, and to prevent a
+	 * module from unloading callbacks while readers are active.
+	 */
+	return rcu_dereference(perf_guest_cbs);
+}
 extern int perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *callbacks);
 extern int perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *callbacks);
 
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 523106a..c552e1b 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6526,18 +6526,25 @@ static void perf_pending_event(struct irq_work *entry)
  * Later on, we might change it to a list if there is
  * another virtualization implementation supporting the callbacks.
  */
-struct perf_guest_info_callbacks *perf_guest_cbs;
+struct perf_guest_info_callbacks __rcu *perf_guest_cbs;
 
 int perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
 {
-	perf_guest_cbs = cbs;
+	if (WARN_ON_ONCE(rcu_access_pointer(perf_guest_cbs)))
+		return -EBUSY;
+
+	rcu_assign_pointer(perf_guest_cbs, cbs);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(perf_register_guest_info_callbacks);
 
 int perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
 {
-	perf_guest_cbs = NULL;
+	if (WARN_ON_ONCE(rcu_access_pointer(perf_guest_cbs) != cbs))
+		return -EINVAL;
+
+	rcu_assign_pointer(perf_guest_cbs, NULL);
+	synchronize_rcu();
 	return 0;
 }
 EXPORT_SYMBOL_GPL(perf_unregister_guest_info_callbacks);

[PATCH v4 02/17] KVM: x86: Register perf callbacks after calling vendor's hardware_setup()

[Sean Christopherson]

Wait to register perf callbacks until after doing vendor hardaware setup.
VMX's hardware_setup() configures Intel Processor Trace (PT) mode, and a
future fix to register the Intel PT guest interrupt hook if and only if
Intel PT is exposed to the guest will consume the configured PT mode.

Delaying registration to hardware setup is effectively a nop as KVM's perf
hooks all pivot on the per-CPU current_vcpu, which is non-NULL only when
KVM is handling an IRQ/NMI in a VM-Exit path.  I.e. current_vcpu will be
NULL throughout both kvm_arch_init() and kvm_arch_hardware_setup().

Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Artem Kashkanov <artem.kashkanov@intel.com>
Cc: stable@vger.kernel.org
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/x86.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c1c4e2b05a63..021b2c1ac9f0 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8567,8 +8567,6 @@ int kvm_arch_init(void *opaque)
 
 	kvm_timer_init();
 
-	perf_register_guest_info_callbacks(&kvm_guest_cbs);
-
 	if (boot_cpu_has(X86_FEATURE_XSAVE)) {
 		host_xcr0 = xgetbv(XCR_XFEATURE_ENABLED_MASK);
 		supported_xcr0 = host_xcr0 & KVM_SUPPORTED_XCR0;
@@ -8600,7 +8598,6 @@ void kvm_arch_exit(void)
 		clear_hv_tscchange_cb();
 #endif
 	kvm_lapic_exit();
-	perf_unregister_guest_info_callbacks(&kvm_guest_cbs);
 
 	if (!boot_cpu_has(X86_FEATURE_CONSTANT_TSC))
 		cpufreq_unregister_notifier(&kvmclock_cpufreq_notifier_block,
@@ -11149,6 +11146,8 @@ int kvm_arch_hardware_setup(void *opaque)
 	memcpy(&kvm_x86_ops, ops->runtime_ops, sizeof(kvm_x86_ops));
 	kvm_ops_static_call_update();
 
+	perf_register_guest_info_callbacks(&kvm_guest_cbs);
+
 	if (!kvm_cpu_cap_has(X86_FEATURE_XSAVES))
 		supported_xss = 0;
 
@@ -11176,6 +11175,8 @@ int kvm_arch_hardware_setup(void *opaque)
 
 void kvm_arch_hardware_unsetup(void)
 {
+	perf_unregister_guest_info_callbacks(&kvm_guest_cbs);
+
 	static_call(kvm_x86_hardware_unsetup)();
 }
 
-- 
2.34.0.rc0.344.g81b53c2807-goog

[tip: perf/core] KVM: x86: Register perf callbacks after calling vendor's hardware_setup()

[tip-bot2 for Sean Christopherson]

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     5c7df80e2ce4c954c80eb4ecf5fa002a5ff5d2d6
Gitweb:        https://git.kernel.org/tip/5c7df80e2ce4c954c80eb4ecf5fa002a5ff5d2d6
Author:        Sean Christopherson <seanjc@google.com>
AuthorDate:    Thu, 11 Nov 2021 02:07:23 
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Wed, 17 Nov 2021 14:49:06 +01:00

KVM: x86: Register perf callbacks after calling vendor's hardware_setup()

Wait to register perf callbacks until after doing vendor hardaware setup.
VMX's hardware_setup() configures Intel Processor Trace (PT) mode, and a
future fix to register the Intel PT guest interrupt hook if and only if
Intel PT is exposed to the guest will consume the configured PT mode.

Delaying registration to hardware setup is effectively a nop as KVM's perf
hooks all pivot on the per-CPU current_vcpu, which is non-NULL only when
KVM is handling an IRQ/NMI in a VM-Exit path.  I.e. current_vcpu will be
NULL throughout both kvm_arch_init() and kvm_arch_hardware_setup().

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20211111020738.2512932-3-seanjc@google.com
---
 arch/x86/kvm/x86.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index dc7eb5f..50f0cd1 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8626,8 +8626,6 @@ int kvm_arch_init(void *opaque)
 
 	kvm_timer_init();
 
-	perf_register_guest_info_callbacks(&kvm_guest_cbs);
-
 	if (boot_cpu_has(X86_FEATURE_XSAVE)) {
 		host_xcr0 = xgetbv(XCR_XFEATURE_ENABLED_MASK);
 		supported_xcr0 = host_xcr0 & KVM_SUPPORTED_XCR0;
@@ -8659,7 +8657,6 @@ void kvm_arch_exit(void)
 		clear_hv_tscchange_cb();
 #endif
 	kvm_lapic_exit();
-	perf_unregister_guest_info_callbacks(&kvm_guest_cbs);
 
 	if (!boot_cpu_has(X86_FEATURE_CONSTANT_TSC))
 		cpufreq_unregister_notifier(&kvmclock_cpufreq_notifier_block,
@@ -11225,6 +11222,8 @@ int kvm_arch_hardware_setup(void *opaque)
 	memcpy(&kvm_x86_ops, ops->runtime_ops, sizeof(kvm_x86_ops));
 	kvm_ops_static_call_update();
 
+	perf_register_guest_info_callbacks(&kvm_guest_cbs);
+
 	if (!kvm_cpu_cap_has(X86_FEATURE_XSAVES))
 		supported_xss = 0;
 
@@ -11252,6 +11251,8 @@ int kvm_arch_hardware_setup(void *opaque)
 
 void kvm_arch_hardware_unsetup(void)
 {
+	perf_unregister_guest_info_callbacks(&kvm_guest_cbs);
+
 	static_call(kvm_x86_hardware_unsetup)();
 }
 

[PATCH v4 03/17] KVM: x86: Register Processor Trace interrupt hook iff PT enabled in guest

[Sean Christopherson]

Override the Processor Trace (PT) interrupt handler for guest mode if and
only if PT is configured for host+guest mode, i.e. is being used
independently by both host and guest.  If PT is configured for system
mode, the host fully controls PT and must handle all events.

Fixes: 8479e04e7d6b ("KVM: x86: Inject PMI for KVM guest")
Cc: stable@vger.kernel.org
Cc: Like Xu <like.xu.linux@gmail.com>
Reported-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Reported-by: Artem Kashkanov <artem.kashkanov@intel.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/include/asm/kvm_host.h | 1 +
 arch/x86/kvm/vmx/vmx.c          | 1 +
 arch/x86/kvm/x86.c              | 5 ++++-
 3 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 2acf37cc1991..bf0a9ce53750 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1514,6 +1514,7 @@ struct kvm_x86_init_ops {
 	int (*disabled_by_bios)(void);
 	int (*check_processor_compatibility)(void);
 	int (*hardware_setup)(void);
+	bool (*intel_pt_intr_in_guest)(void);
 
 	struct kvm_x86_ops *runtime_ops;
 };
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 76861b66bbcf..0927d07b2efb 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7918,6 +7918,7 @@ static struct kvm_x86_init_ops vmx_init_ops __initdata = {
 	.disabled_by_bios = vmx_disabled_by_bios,
 	.check_processor_compatibility = vmx_check_processor_compat,
 	.hardware_setup = hardware_setup,
+	.intel_pt_intr_in_guest = vmx_pt_mode_is_host_guest,
 
 	.runtime_ops = &vmx_x86_ops,
 };
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 021b2c1ac9f0..021d3f5364b2 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8451,7 +8451,7 @@ static struct perf_guest_info_callbacks kvm_guest_cbs = {
 	.is_in_guest		= kvm_is_in_guest,
 	.is_user_mode		= kvm_is_user_mode,
 	.get_guest_ip		= kvm_get_guest_ip,
-	.handle_intel_pt_intr	= kvm_handle_intel_pt_intr,
+	.handle_intel_pt_intr	= NULL,
 };
 
 #ifdef CONFIG_X86_64
@@ -11146,6 +11146,8 @@ int kvm_arch_hardware_setup(void *opaque)
 	memcpy(&kvm_x86_ops, ops->runtime_ops, sizeof(kvm_x86_ops));
 	kvm_ops_static_call_update();
 
+	if (ops->intel_pt_intr_in_guest && ops->intel_pt_intr_in_guest())
+		kvm_guest_cbs.handle_intel_pt_intr = kvm_handle_intel_pt_intr;
 	perf_register_guest_info_callbacks(&kvm_guest_cbs);
 
 	if (!kvm_cpu_cap_has(X86_FEATURE_XSAVES))
@@ -11176,6 +11178,7 @@ int kvm_arch_hardware_setup(void *opaque)
 void kvm_arch_hardware_unsetup(void)
 {
 	perf_unregister_guest_info_callbacks(&kvm_guest_cbs);
+	kvm_guest_cbs.handle_intel_pt_intr = NULL;
 
 	static_call(kvm_x86_hardware_unsetup)();
 }
-- 
2.34.0.rc0.344.g81b53c2807-goog

[tip: perf/core] KVM: x86: Register Processor Trace interrupt hook iff PT enabled in guest

[tip-bot2 for Sean Christopherson]

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     f4b027c5c8199abd4fb6f00d67d380548dbfdfa8
Gitweb:        https://git.kernel.org/tip/f4b027c5c8199abd4fb6f00d67d380548dbfdfa8
Author:        Sean Christopherson <seanjc@google.com>
AuthorDate:    Thu, 11 Nov 2021 02:07:24 
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Wed, 17 Nov 2021 14:49:06 +01:00

KVM: x86: Register Processor Trace interrupt hook iff PT enabled in guest

Override the Processor Trace (PT) interrupt handler for guest mode if and
only if PT is configured for host+guest mode, i.e. is being used
independently by both host and guest.  If PT is configured for system
mode, the host fully controls PT and must handle all events.

Fixes: 8479e04e7d6b ("KVM: x86: Inject PMI for KVM guest")
Reported-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Reported-by: Artem Kashkanov <artem.kashkanov@intel.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20211111020738.2512932-4-seanjc@google.com
---
 arch/x86/include/asm/kvm_host.h | 1 +
 arch/x86/kvm/vmx/vmx.c          | 1 +
 arch/x86/kvm/x86.c              | 5 ++++-
 3 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index e5d8700..41e858d 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1516,6 +1516,7 @@ struct kvm_x86_init_ops {
 	int (*disabled_by_bios)(void);
 	int (*check_processor_compatibility)(void);
 	int (*hardware_setup)(void);
+	bool (*intel_pt_intr_in_guest)(void);
 
 	struct kvm_x86_ops *runtime_ops;
 };
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index ba66c17..7d90c8d 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7865,6 +7865,7 @@ static struct kvm_x86_init_ops vmx_init_ops __initdata = {
 	.disabled_by_bios = vmx_disabled_by_bios,
 	.check_processor_compatibility = vmx_check_processor_compat,
 	.hardware_setup = hardware_setup,
+	.intel_pt_intr_in_guest = vmx_pt_mode_is_host_guest,
 
 	.runtime_ops = &vmx_x86_ops,
 };
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 50f0cd1..760c4e3 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8510,7 +8510,7 @@ static struct perf_guest_info_callbacks kvm_guest_cbs = {
 	.is_in_guest		= kvm_is_in_guest,
 	.is_user_mode		= kvm_is_user_mode,
 	.get_guest_ip		= kvm_get_guest_ip,
-	.handle_intel_pt_intr	= kvm_handle_intel_pt_intr,
+	.handle_intel_pt_intr	= NULL,
 };
 
 #ifdef CONFIG_X86_64
@@ -11222,6 +11222,8 @@ int kvm_arch_hardware_setup(void *opaque)
 	memcpy(&kvm_x86_ops, ops->runtime_ops, sizeof(kvm_x86_ops));
 	kvm_ops_static_call_update();
 
+	if (ops->intel_pt_intr_in_guest && ops->intel_pt_intr_in_guest())
+		kvm_guest_cbs.handle_intel_pt_intr = kvm_handle_intel_pt_intr;
 	perf_register_guest_info_callbacks(&kvm_guest_cbs);
 
 	if (!kvm_cpu_cap_has(X86_FEATURE_XSAVES))
@@ -11252,6 +11254,7 @@ int kvm_arch_hardware_setup(void *opaque)
 void kvm_arch_hardware_unsetup(void)
 {
 	perf_unregister_guest_info_callbacks(&kvm_guest_cbs);
+	kvm_guest_cbs.handle_intel_pt_intr = NULL;
 
 	static_call(kvm_x86_hardware_unsetup)();
 }

[PATCH v4 04/17] perf: Stop pretending that perf can handle multiple guest callbacks

[Sean Christopherson]

Drop the 'int' return value from the perf (un)register callbacks helpers
and stop pretending perf can support multiple callbacks.  The 'int'
returns are not future proofing anything as none of the callers take
action on an error.  It's also not obvious that there will ever be
co-tenant hypervisors, and if there are, that allowing multiple callbacks
to be registered is desirable or even correct.

Opportunistically rename callbacks=>cbs in the affected declarations to
match their definitions.

No functional change intended.

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/arm64/include/asm/kvm_host.h |  4 ++--
 arch/arm64/kvm/perf.c             |  8 ++++----
 include/linux/perf_event.h        | 12 ++++++------
 kernel/events/core.c              | 15 ++++-----------
 4 files changed, 16 insertions(+), 23 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 4be8486042a7..5a76d9a76fd9 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -675,8 +675,8 @@ unsigned long kvm_mmio_read_buf(const void *buf, unsigned int len);
 int kvm_handle_mmio_return(struct kvm_vcpu *vcpu);
 int io_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa);
 
-int kvm_perf_init(void);
-int kvm_perf_teardown(void);
+void kvm_perf_init(void);
+void kvm_perf_teardown(void);
 
 long kvm_hypercall_pv_features(struct kvm_vcpu *vcpu);
 gpa_t kvm_init_stolen_time(struct kvm_vcpu *vcpu);
diff --git a/arch/arm64/kvm/perf.c b/arch/arm64/kvm/perf.c
index c84fe24b2ea1..a0d660cf889e 100644
--- a/arch/arm64/kvm/perf.c
+++ b/arch/arm64/kvm/perf.c
@@ -48,12 +48,12 @@ static struct perf_guest_info_callbacks kvm_guest_cbs = {
 	.get_guest_ip	= kvm_get_guest_ip,
 };
 
-int kvm_perf_init(void)
+void kvm_perf_init(void)
 {
-	return perf_register_guest_info_callbacks(&kvm_guest_cbs);
+	perf_register_guest_info_callbacks(&kvm_guest_cbs);
 }
 
-int kvm_perf_teardown(void)
+void kvm_perf_teardown(void)
 {
-	return perf_unregister_guest_info_callbacks(&kvm_guest_cbs);
+	perf_unregister_guest_info_callbacks(&kvm_guest_cbs);
 }
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 318c489b735b..98c204488496 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1252,8 +1252,8 @@ static inline struct perf_guest_info_callbacks *perf_get_guest_cbs(void)
 	 */
 	return rcu_dereference(perf_guest_cbs);
 }
-extern int perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *callbacks);
-extern int perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *callbacks);
+extern void perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs);
+extern void perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs);
 
 extern void perf_event_exec(void);
 extern void perf_event_comm(struct task_struct *tsk, bool exec);
@@ -1497,10 +1497,10 @@ perf_sw_event(u32 event_id, u64 nr, struct pt_regs *regs, u64 addr)	{ }
 static inline void
 perf_bp_event(struct perf_event *event, void *data)			{ }
 
-static inline int perf_register_guest_info_callbacks
-(struct perf_guest_info_callbacks *callbacks)				{ return 0; }
-static inline int perf_unregister_guest_info_callbacks
-(struct perf_guest_info_callbacks *callbacks)				{ return 0; }
+static inline void perf_register_guest_info_callbacks
+(struct perf_guest_info_callbacks *cbs)					{ }
+static inline void perf_unregister_guest_info_callbacks
+(struct perf_guest_info_callbacks *cbs)					{ }
 
 static inline void perf_event_mmap(struct vm_area_struct *vma)		{ }
 
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 0cc775f702f8..eb6b9cfd0054 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6521,31 +6521,24 @@ static void perf_pending_event(struct irq_work *entry)
 		perf_swevent_put_recursion_context(rctx);
 }
 
-/*
- * We assume there is only KVM supporting the callbacks.
- * Later on, we might change it to a list if there is
- * another virtualization implementation supporting the callbacks.
- */
 struct perf_guest_info_callbacks __rcu *perf_guest_cbs;
 
-int perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
+void perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
 {
 	if (WARN_ON_ONCE(rcu_access_pointer(perf_guest_cbs)))
-		return -EBUSY;
+		return;
 
 	rcu_assign_pointer(perf_guest_cbs, cbs);
-	return 0;
 }
 EXPORT_SYMBOL_GPL(perf_register_guest_info_callbacks);
 
-int perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
+void perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
 {
 	if (WARN_ON_ONCE(rcu_access_pointer(perf_guest_cbs) != cbs))
-		return -EINVAL;
+		return;
 
 	rcu_assign_pointer(perf_guest_cbs, NULL);
 	synchronize_rcu();
-	return 0;
 }
 EXPORT_SYMBOL_GPL(perf_unregister_guest_info_callbacks);
 
-- 
2.34.0.rc0.344.g81b53c2807-goog

[tip: perf/core] perf: Stop pretending that perf can handle multiple guest callbacks

[tip-bot2 for Sean Christopherson]

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     2934e3d09350c1a7ca2433fbeabfcd831e48a575
Gitweb:        https://git.kernel.org/tip/2934e3d09350c1a7ca2433fbeabfcd831e48a575
Author:        Sean Christopherson <seanjc@google.com>
AuthorDate:    Thu, 11 Nov 2021 02:07:25 
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Wed, 17 Nov 2021 14:49:07 +01:00

perf: Stop pretending that perf can handle multiple guest callbacks

Drop the 'int' return value from the perf (un)register callbacks helpers
and stop pretending perf can support multiple callbacks.  The 'int'
returns are not future proofing anything as none of the callers take
action on an error.  It's also not obvious that there will ever be
co-tenant hypervisors, and if there are, that allowing multiple callbacks
to be registered is desirable or even correct.

Opportunistically rename callbacks=>cbs in the affected declarations to
match their definitions.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Link: https://lore.kernel.org/r/20211111020738.2512932-5-seanjc@google.com
---
 arch/arm64/include/asm/kvm_host.h |  4 ++--
 arch/arm64/kvm/perf.c             |  8 ++++----
 include/linux/perf_event.h        | 12 ++++++------
 kernel/events/core.c              | 15 ++++-----------
 4 files changed, 16 insertions(+), 23 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 2a5f7f3..f680f30 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -675,8 +675,8 @@ unsigned long kvm_mmio_read_buf(const void *buf, unsigned int len);
 int kvm_handle_mmio_return(struct kvm_vcpu *vcpu);
 int io_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa);
 
-int kvm_perf_init(void);
-int kvm_perf_teardown(void);
+void kvm_perf_init(void);
+void kvm_perf_teardown(void);
 
 long kvm_hypercall_pv_features(struct kvm_vcpu *vcpu);
 gpa_t kvm_init_stolen_time(struct kvm_vcpu *vcpu);
diff --git a/arch/arm64/kvm/perf.c b/arch/arm64/kvm/perf.c
index c84fe24..a0d660c 100644
--- a/arch/arm64/kvm/perf.c
+++ b/arch/arm64/kvm/perf.c
@@ -48,12 +48,12 @@ static struct perf_guest_info_callbacks kvm_guest_cbs = {
 	.get_guest_ip	= kvm_get_guest_ip,
 };
 
-int kvm_perf_init(void)
+void kvm_perf_init(void)
 {
-	return perf_register_guest_info_callbacks(&kvm_guest_cbs);
+	perf_register_guest_info_callbacks(&kvm_guest_cbs);
 }
 
-int kvm_perf_teardown(void)
+void kvm_perf_teardown(void)
 {
-	return perf_unregister_guest_info_callbacks(&kvm_guest_cbs);
+	perf_unregister_guest_info_callbacks(&kvm_guest_cbs);
 }
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 318c489..98c2044 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1252,8 +1252,8 @@ static inline struct perf_guest_info_callbacks *perf_get_guest_cbs(void)
 	 */
 	return rcu_dereference(perf_guest_cbs);
 }
-extern int perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *callbacks);
-extern int perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *callbacks);
+extern void perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs);
+extern void perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs);
 
 extern void perf_event_exec(void);
 extern void perf_event_comm(struct task_struct *tsk, bool exec);
@@ -1497,10 +1497,10 @@ perf_sw_event(u32 event_id, u64 nr, struct pt_regs *regs, u64 addr)	{ }
 static inline void
 perf_bp_event(struct perf_event *event, void *data)			{ }
 
-static inline int perf_register_guest_info_callbacks
-(struct perf_guest_info_callbacks *callbacks)				{ return 0; }
-static inline int perf_unregister_guest_info_callbacks
-(struct perf_guest_info_callbacks *callbacks)				{ return 0; }
+static inline void perf_register_guest_info_callbacks
+(struct perf_guest_info_callbacks *cbs)					{ }
+static inline void perf_unregister_guest_info_callbacks
+(struct perf_guest_info_callbacks *cbs)					{ }
 
 static inline void perf_event_mmap(struct vm_area_struct *vma)		{ }
 
diff --git a/kernel/events/core.c b/kernel/events/core.c
index c552e1b..17e5b20 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6521,31 +6521,24 @@ static void perf_pending_event(struct irq_work *entry)
 		perf_swevent_put_recursion_context(rctx);
 }
 
-/*
- * We assume there is only KVM supporting the callbacks.
- * Later on, we might change it to a list if there is
- * another virtualization implementation supporting the callbacks.
- */
 struct perf_guest_info_callbacks __rcu *perf_guest_cbs;
 
-int perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
+void perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
 {
 	if (WARN_ON_ONCE(rcu_access_pointer(perf_guest_cbs)))
-		return -EBUSY;
+		return;
 
 	rcu_assign_pointer(perf_guest_cbs, cbs);
-	return 0;
 }
 EXPORT_SYMBOL_GPL(perf_register_guest_info_callbacks);
 
-int perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
+void perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
 {
 	if (WARN_ON_ONCE(rcu_access_pointer(perf_guest_cbs) != cbs))
-		return -EINVAL;
+		return;
 
 	rcu_assign_pointer(perf_guest_cbs, NULL);
 	synchronize_rcu();
-	return 0;
 }
 EXPORT_SYMBOL_GPL(perf_unregister_guest_info_callbacks);
 

[PATCH v4 05/17] perf: Drop dead and useless guest "support" from arm, csky, nds32 and riscv

[Sean Christopherson]

Drop "support" for guest callbacks from architectures that don't implement
the guest callbacks.  Future patches will convert the callbacks to
static_call; rather than churn a bunch of arch code (that was presumably
copy+pasted from x86), remove it wholesale as it's useless and at best
wasting cycles.

A future patch will also add a Kconfig to force architcture to opt into
the callbacks to make it more difficult for uses "support" to sneak in in
the future.

No functional change intended.

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/arm/kernel/perf_callchain.c   | 33 ++++-------------------------
 arch/csky/kernel/perf_callchain.c  | 12 -----------
 arch/nds32/kernel/perf_event_cpu.c | 34 ++++--------------------------
 arch/riscv/kernel/perf_callchain.c | 13 ------------
 4 files changed, 8 insertions(+), 84 deletions(-)

diff --git a/arch/arm/kernel/perf_callchain.c b/arch/arm/kernel/perf_callchain.c
index 1626dfc6f6ce..bc6b246ab55e 100644
--- a/arch/arm/kernel/perf_callchain.c
+++ b/arch/arm/kernel/perf_callchain.c
@@ -62,14 +62,8 @@ user_backtrace(struct frame_tail __user *tail,
 void
 perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	struct frame_tail __user *tail;
 
-	if (guest_cbs && guest_cbs->is_in_guest()) {
-		/* We don't support guest os callchain now */
-		return;
-	}
-
 	perf_callchain_store(entry, regs->ARM_pc);
 
 	if (!current->mm)
@@ -99,44 +93,25 @@ callchain_trace(struct stackframe *fr,
 void
 perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	struct stackframe fr;
 
-	if (guest_cbs && guest_cbs->is_in_guest()) {
-		/* We don't support guest os callchain now */
-		return;
-	}
-
 	arm_get_current_stackframe(regs, &fr);
 	walk_stackframe(&fr, callchain_trace, entry);
 }
 
 unsigned long perf_instruction_pointer(struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
-
-	if (guest_cbs && guest_cbs->is_in_guest())
-		return guest_cbs->get_guest_ip();
-
 	return instruction_pointer(regs);
 }
 
 unsigned long perf_misc_flags(struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	int misc = 0;
 
-	if (guest_cbs && guest_cbs->is_in_guest()) {
-		if (guest_cbs->is_user_mode())
-			misc |= PERF_RECORD_MISC_GUEST_USER;
-		else
-			misc |= PERF_RECORD_MISC_GUEST_KERNEL;
-	} else {
-		if (user_mode(regs))
-			misc |= PERF_RECORD_MISC_USER;
-		else
-			misc |= PERF_RECORD_MISC_KERNEL;
-	}
+	if (user_mode(regs))
+		misc |= PERF_RECORD_MISC_USER;
+	else
+		misc |= PERF_RECORD_MISC_KERNEL;
 
 	return misc;
 }
diff --git a/arch/csky/kernel/perf_callchain.c b/arch/csky/kernel/perf_callchain.c
index 35318a635a5f..92057de08f4f 100644
--- a/arch/csky/kernel/perf_callchain.c
+++ b/arch/csky/kernel/perf_callchain.c
@@ -86,13 +86,8 @@ static unsigned long user_backtrace(struct perf_callchain_entry_ctx *entry,
 void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
 			 struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	unsigned long fp = 0;
 
-	/* C-SKY does not support virtualization. */
-	if (guest_cbs && guest_cbs->is_in_guest())
-		return;
-
 	fp = regs->regs[4];
 	perf_callchain_store(entry, regs->pc);
 
@@ -111,15 +106,8 @@ void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
 void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
 			   struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	struct stackframe fr;
 
-	/* C-SKY does not support virtualization. */
-	if (guest_cbs && guest_cbs->is_in_guest()) {
-		pr_warn("C-SKY does not support perf in guest mode!");
-		return;
-	}
-
 	fr.fp = regs->regs[4];
 	fr.lr = regs->lr;
 	walk_stackframe(&fr, entry);
diff --git a/arch/nds32/kernel/perf_event_cpu.c b/arch/nds32/kernel/perf_event_cpu.c
index f38791960781..a78a879e7ef1 100644
--- a/arch/nds32/kernel/perf_event_cpu.c
+++ b/arch/nds32/kernel/perf_event_cpu.c
@@ -1363,7 +1363,6 @@ void
 perf_callchain_user(struct perf_callchain_entry_ctx *entry,
 		    struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	unsigned long fp = 0;
 	unsigned long gp = 0;
 	unsigned long lp = 0;
@@ -1372,11 +1371,6 @@ perf_callchain_user(struct perf_callchain_entry_ctx *entry,
 
 	leaf_fp = 0;
 
-	if (guest_cbs && guest_cbs->is_in_guest()) {
-		/* We don't support guest os callchain now */
-		return;
-	}
-
 	perf_callchain_store(entry, regs->ipc);
 	fp = regs->fp;
 	gp = regs->gp;
@@ -1480,13 +1474,8 @@ void
 perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
 		      struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	struct stackframe fr;
 
-	if (guest_cbs && guest_cbs->is_in_guest()) {
-		/* We don't support guest os callchain now */
-		return;
-	}
 	fr.fp = regs->fp;
 	fr.lp = regs->lp;
 	fr.sp = regs->sp;
@@ -1495,32 +1484,17 @@ perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
 
 unsigned long perf_instruction_pointer(struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
-
-	/* However, NDS32 does not support virtualization */
-	if (guest_cbs && guest_cbs->is_in_guest())
-		return guest_cbs->get_guest_ip();
-
 	return instruction_pointer(regs);
 }
 
 unsigned long perf_misc_flags(struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	int misc = 0;
 
-	/* However, NDS32 does not support virtualization */
-	if (guest_cbs && guest_cbs->is_in_guest()) {
-		if (guest_cbs->is_user_mode())
-			misc |= PERF_RECORD_MISC_GUEST_USER;
-		else
-			misc |= PERF_RECORD_MISC_GUEST_KERNEL;
-	} else {
-		if (user_mode(regs))
-			misc |= PERF_RECORD_MISC_USER;
-		else
-			misc |= PERF_RECORD_MISC_KERNEL;
-	}
+	if (user_mode(regs))
+		misc |= PERF_RECORD_MISC_USER;
+	else
+		misc |= PERF_RECORD_MISC_KERNEL;
 
 	return misc;
 }
diff --git a/arch/riscv/kernel/perf_callchain.c b/arch/riscv/kernel/perf_callchain.c
index 8ecfc4c128bc..1fc075b8f764 100644
--- a/arch/riscv/kernel/perf_callchain.c
+++ b/arch/riscv/kernel/perf_callchain.c
@@ -56,13 +56,8 @@ static unsigned long user_backtrace(struct perf_callchain_entry_ctx *entry,
 void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
 			 struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	unsigned long fp = 0;
 
-	/* RISC-V does not support perf in guest mode. */
-	if (guest_cbs && guest_cbs->is_in_guest())
-		return;
-
 	fp = regs->s0;
 	perf_callchain_store(entry, regs->epc);
 
@@ -79,13 +74,5 @@ static bool fill_callchain(void *entry, unsigned long pc)
 void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
 			   struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
-
-	/* RISC-V does not support perf in guest mode. */
-	if (guest_cbs && guest_cbs->is_in_guest()) {
-		pr_warn("RISC-V does not support perf in guest mode!");
-		return;
-	}
-
 	walk_stackframe(NULL, regs, fill_callchain, entry);
 }
-- 
2.34.0.rc0.344.g81b53c2807-goog

[tip: perf/core] perf: Drop dead and useless guest "support" from arm, csky, nds32 and riscv

[tip-bot2 for Sean Christopherson]

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     84af21d850ee1ccc990df37dd47c13fdfe93be75
Gitweb:        https://git.kernel.org/tip/84af21d850ee1ccc990df37dd47c13fdfe93be75
Author:        Sean Christopherson <seanjc@google.com>
AuthorDate:    Thu, 11 Nov 2021 02:07:26 
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Wed, 17 Nov 2021 14:49:07 +01:00

perf: Drop dead and useless guest "support" from arm, csky, nds32 and riscv

Drop "support" for guest callbacks from architectures that don't implement
the guest callbacks.  Future patches will convert the callbacks to
static_call; rather than churn a bunch of arch code (that was presumably
copy+pasted from x86), remove it wholesale as it's useless and at best
wasting cycles.

A future patch will also add a Kconfig to force architcture to opt into
the callbacks to make it more difficult for uses "support" to sneak in in
the future.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Link: https://lore.kernel.org/r/20211111020738.2512932-6-seanjc@google.com
---
 arch/arm/kernel/perf_callchain.c   | 33 +++-------------------------
 arch/csky/kernel/perf_callchain.c  | 12 +----------
 arch/nds32/kernel/perf_event_cpu.c | 34 +++--------------------------
 arch/riscv/kernel/perf_callchain.c | 13 +-----------
 4 files changed, 8 insertions(+), 84 deletions(-)

diff --git a/arch/arm/kernel/perf_callchain.c b/arch/arm/kernel/perf_callchain.c
index 1626dfc..bc6b246 100644
--- a/arch/arm/kernel/perf_callchain.c
+++ b/arch/arm/kernel/perf_callchain.c
@@ -62,14 +62,8 @@ user_backtrace(struct frame_tail __user *tail,
 void
 perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	struct frame_tail __user *tail;
 
-	if (guest_cbs && guest_cbs->is_in_guest()) {
-		/* We don't support guest os callchain now */
-		return;
-	}
-
 	perf_callchain_store(entry, regs->ARM_pc);
 
 	if (!current->mm)
@@ -99,44 +93,25 @@ callchain_trace(struct stackframe *fr,
 void
 perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	struct stackframe fr;
 
-	if (guest_cbs && guest_cbs->is_in_guest()) {
-		/* We don't support guest os callchain now */
-		return;
-	}
-
 	arm_get_current_stackframe(regs, &fr);
 	walk_stackframe(&fr, callchain_trace, entry);
 }
 
 unsigned long perf_instruction_pointer(struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
-
-	if (guest_cbs && guest_cbs->is_in_guest())
-		return guest_cbs->get_guest_ip();
-
 	return instruction_pointer(regs);
 }
 
 unsigned long perf_misc_flags(struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	int misc = 0;
 
-	if (guest_cbs && guest_cbs->is_in_guest()) {
-		if (guest_cbs->is_user_mode())
-			misc |= PERF_RECORD_MISC_GUEST_USER;
-		else
-			misc |= PERF_RECORD_MISC_GUEST_KERNEL;
-	} else {
-		if (user_mode(regs))
-			misc |= PERF_RECORD_MISC_USER;
-		else
-			misc |= PERF_RECORD_MISC_KERNEL;
-	}
+	if (user_mode(regs))
+		misc |= PERF_RECORD_MISC_USER;
+	else
+		misc |= PERF_RECORD_MISC_KERNEL;
 
 	return misc;
 }
diff --git a/arch/csky/kernel/perf_callchain.c b/arch/csky/kernel/perf_callchain.c
index 35318a6..92057de 100644
--- a/arch/csky/kernel/perf_callchain.c
+++ b/arch/csky/kernel/perf_callchain.c
@@ -86,13 +86,8 @@ static unsigned long user_backtrace(struct perf_callchain_entry_ctx *entry,
 void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
 			 struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	unsigned long fp = 0;
 
-	/* C-SKY does not support virtualization. */
-	if (guest_cbs && guest_cbs->is_in_guest())
-		return;
-
 	fp = regs->regs[4];
 	perf_callchain_store(entry, regs->pc);
 
@@ -111,15 +106,8 @@ void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
 void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
 			   struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	struct stackframe fr;
 
-	/* C-SKY does not support virtualization. */
-	if (guest_cbs && guest_cbs->is_in_guest()) {
-		pr_warn("C-SKY does not support perf in guest mode!");
-		return;
-	}
-
 	fr.fp = regs->regs[4];
 	fr.lr = regs->lr;
 	walk_stackframe(&fr, entry);
diff --git a/arch/nds32/kernel/perf_event_cpu.c b/arch/nds32/kernel/perf_event_cpu.c
index f387919..a78a879 100644
--- a/arch/nds32/kernel/perf_event_cpu.c
+++ b/arch/nds32/kernel/perf_event_cpu.c
@@ -1363,7 +1363,6 @@ void
 perf_callchain_user(struct perf_callchain_entry_ctx *entry,
 		    struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	unsigned long fp = 0;
 	unsigned long gp = 0;
 	unsigned long lp = 0;
@@ -1372,11 +1371,6 @@ perf_callchain_user(struct perf_callchain_entry_ctx *entry,
 
 	leaf_fp = 0;
 
-	if (guest_cbs && guest_cbs->is_in_guest()) {
-		/* We don't support guest os callchain now */
-		return;
-	}
-
 	perf_callchain_store(entry, regs->ipc);
 	fp = regs->fp;
 	gp = regs->gp;
@@ -1480,13 +1474,8 @@ void
 perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
 		      struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	struct stackframe fr;
 
-	if (guest_cbs && guest_cbs->is_in_guest()) {
-		/* We don't support guest os callchain now */
-		return;
-	}
 	fr.fp = regs->fp;
 	fr.lp = regs->lp;
 	fr.sp = regs->sp;
@@ -1495,32 +1484,17 @@ perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
 
 unsigned long perf_instruction_pointer(struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
-
-	/* However, NDS32 does not support virtualization */
-	if (guest_cbs && guest_cbs->is_in_guest())
-		return guest_cbs->get_guest_ip();
-
 	return instruction_pointer(regs);
 }
 
 unsigned long perf_misc_flags(struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	int misc = 0;
 
-	/* However, NDS32 does not support virtualization */
-	if (guest_cbs && guest_cbs->is_in_guest()) {
-		if (guest_cbs->is_user_mode())
-			misc |= PERF_RECORD_MISC_GUEST_USER;
-		else
-			misc |= PERF_RECORD_MISC_GUEST_KERNEL;
-	} else {
-		if (user_mode(regs))
-			misc |= PERF_RECORD_MISC_USER;
-		else
-			misc |= PERF_RECORD_MISC_KERNEL;
-	}
+	if (user_mode(regs))
+		misc |= PERF_RECORD_MISC_USER;
+	else
+		misc |= PERF_RECORD_MISC_KERNEL;
 
 	return misc;
 }
diff --git a/arch/riscv/kernel/perf_callchain.c b/arch/riscv/kernel/perf_callchain.c
index 8ecfc4c..1fc075b 100644
--- a/arch/riscv/kernel/perf_callchain.c
+++ b/arch/riscv/kernel/perf_callchain.c
@@ -56,13 +56,8 @@ static unsigned long user_backtrace(struct perf_callchain_entry_ctx *entry,
 void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
 			 struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	unsigned long fp = 0;
 
-	/* RISC-V does not support perf in guest mode. */
-	if (guest_cbs && guest_cbs->is_in_guest())
-		return;
-
 	fp = regs->s0;
 	perf_callchain_store(entry, regs->epc);
 
@@ -79,13 +74,5 @@ static bool fill_callchain(void *entry, unsigned long pc)
 void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
 			   struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
-
-	/* RISC-V does not support perf in guest mode. */
-	if (guest_cbs && guest_cbs->is_in_guest()) {
-		pr_warn("RISC-V does not support perf in guest mode!");
-		return;
-	}
-
 	walk_stackframe(NULL, regs, fill_callchain, entry);
 }

[PATCH v4 06/17] perf/core: Rework guest callbacks to prepare for static_call support

[Sean Christopherson]

From: Like Xu <like.xu@linux.intel.com>

To prepare for using static_calls to optimize perf's guest callbacks,
replace ->is_in_guest and ->is_user_mode with a new multiplexed hook
->state, tweak ->handle_intel_pt_intr to play nice with being called when
there is no active guest, and drop "guest" from ->get_guest_ip.

Return '0' from ->state and ->handle_intel_pt_intr to indicate "not in
guest" so that DEFINE_STATIC_CALL_RET0 can be used to define the static
calls, i.e. no callback == !guest.

Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Originally-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Like Xu <like.xu@linux.intel.com>
Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
[sean: extracted from static_call patch, fixed get_ip() bug, wrote changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/arm64/kernel/perf_callchain.c | 13 +++++-----
 arch/arm64/kvm/perf.c              | 35 +++++++++++---------------
 arch/x86/events/core.c             | 13 +++++-----
 arch/x86/events/intel/core.c       |  5 +---
 arch/x86/include/asm/kvm_host.h    |  2 +-
 arch/x86/kvm/pmu.c                 |  2 +-
 arch/x86/kvm/x86.c                 | 40 ++++++++++++++++--------------
 arch/x86/xen/pmu.c                 | 32 ++++++++++--------------
 include/linux/perf_event.h         | 10 +++++---
 9 files changed, 73 insertions(+), 79 deletions(-)

diff --git a/arch/arm64/kernel/perf_callchain.c b/arch/arm64/kernel/perf_callchain.c
index 86d9f2013172..274dc3e11b6d 100644
--- a/arch/arm64/kernel/perf_callchain.c
+++ b/arch/arm64/kernel/perf_callchain.c
@@ -104,7 +104,7 @@ void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
 {
 	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 
-	if (guest_cbs && guest_cbs->is_in_guest()) {
+	if (guest_cbs && guest_cbs->state()) {
 		/* We don't support guest os callchain now */
 		return;
 	}
@@ -152,7 +152,7 @@ void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
 	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	struct stackframe frame;
 
-	if (guest_cbs && guest_cbs->is_in_guest()) {
+	if (guest_cbs && guest_cbs->state()) {
 		/* We don't support guest os callchain now */
 		return;
 	}
@@ -165,8 +165,8 @@ unsigned long perf_instruction_pointer(struct pt_regs *regs)
 {
 	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 
-	if (guest_cbs && guest_cbs->is_in_guest())
-		return guest_cbs->get_guest_ip();
+	if (guest_cbs && guest_cbs->state())
+		return guest_cbs->get_ip();
 
 	return instruction_pointer(regs);
 }
@@ -174,10 +174,11 @@ unsigned long perf_instruction_pointer(struct pt_regs *regs)
 unsigned long perf_misc_flags(struct pt_regs *regs)
 {
 	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
+	unsigned int guest_state = guest_cbs ? guest_cbs->state() : 0;
 	int misc = 0;
 
-	if (guest_cbs && guest_cbs->is_in_guest()) {
-		if (guest_cbs->is_user_mode())
+	if (guest_state) {
+		if (guest_state & PERF_GUEST_USER)
 			misc |= PERF_RECORD_MISC_GUEST_USER;
 		else
 			misc |= PERF_RECORD_MISC_GUEST_KERNEL;
diff --git a/arch/arm64/kvm/perf.c b/arch/arm64/kvm/perf.c
index a0d660cf889e..dfa9bce8559e 100644
--- a/arch/arm64/kvm/perf.c
+++ b/arch/arm64/kvm/perf.c
@@ -13,39 +13,34 @@
 
 DEFINE_STATIC_KEY_FALSE(kvm_arm_pmu_available);
 
-static int kvm_is_in_guest(void)
+static unsigned int kvm_guest_state(void)
 {
-        return kvm_get_running_vcpu() != NULL;
-}
+	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
+	unsigned int state;
 
-static int kvm_is_user_mode(void)
-{
-	struct kvm_vcpu *vcpu;
-
-	vcpu = kvm_get_running_vcpu();
+	if (!vcpu)
+		return 0;
 
-	if (vcpu)
-		return !vcpu_mode_priv(vcpu);
+	state = PERF_GUEST_ACTIVE;
+	if (!vcpu_mode_priv(vcpu))
+		state |= PERF_GUEST_USER;
 
-	return 0;
+	return state;
 }
 
 static unsigned long kvm_get_guest_ip(void)
 {
-	struct kvm_vcpu *vcpu;
+	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
 
-	vcpu = kvm_get_running_vcpu();
+	if (WARN_ON_ONCE(!vcpu))
+		return 0;
 
-	if (vcpu)
-		return *vcpu_pc(vcpu);
-
-	return 0;
+	return *vcpu_pc(vcpu);
 }
 
 static struct perf_guest_info_callbacks kvm_guest_cbs = {
-	.is_in_guest	= kvm_is_in_guest,
-	.is_user_mode	= kvm_is_user_mode,
-	.get_guest_ip	= kvm_get_guest_ip,
+	.state		= kvm_guest_state,
+	.get_ip		= kvm_get_guest_ip,
 };
 
 void kvm_perf_init(void)
diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 32cec290d3ad..e29312a1003a 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -2772,7 +2772,7 @@ perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *re
 	struct unwind_state state;
 	unsigned long addr;
 
-	if (guest_cbs && guest_cbs->is_in_guest()) {
+	if (guest_cbs && guest_cbs->state()) {
 		/* TODO: We don't support guest os callchain now */
 		return;
 	}
@@ -2876,7 +2876,7 @@ perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs
 	struct stack_frame frame;
 	const struct stack_frame __user *fp;
 
-	if (guest_cbs && guest_cbs->is_in_guest()) {
+	if (guest_cbs && guest_cbs->state()) {
 		/* TODO: We don't support guest os callchain now */
 		return;
 	}
@@ -2955,8 +2955,8 @@ unsigned long perf_instruction_pointer(struct pt_regs *regs)
 {
 	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 
-	if (guest_cbs && guest_cbs->is_in_guest())
-		return guest_cbs->get_guest_ip();
+	if (guest_cbs && guest_cbs->state())
+		return guest_cbs->get_ip();
 
 	return regs->ip + code_segment_base(regs);
 }
@@ -2964,10 +2964,11 @@ unsigned long perf_instruction_pointer(struct pt_regs *regs)
 unsigned long perf_misc_flags(struct pt_regs *regs)
 {
 	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
+	unsigned int guest_state = guest_cbs ? guest_cbs->state() : 0;
 	int misc = 0;
 
-	if (guest_cbs && guest_cbs->is_in_guest()) {
-		if (guest_cbs->is_user_mode())
+	if (guest_state) {
+		if (guest_state & PERF_GUEST_USER)
 			misc |= PERF_RECORD_MISC_GUEST_USER;
 		else
 			misc |= PERF_RECORD_MISC_GUEST_KERNEL;
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index cde29bd5bb53..24adbd6282d4 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -2906,10 +2906,7 @@ static int handle_pmi_common(struct pt_regs *regs, u64 status)
 		handled++;
 
 		guest_cbs = perf_get_guest_cbs();
-		if (unlikely(guest_cbs && guest_cbs->is_in_guest() &&
-			     guest_cbs->handle_intel_pt_intr))
-			guest_cbs->handle_intel_pt_intr();
-		else
+		if (likely(!guest_cbs || !guest_cbs->handle_intel_pt_intr()))
 			intel_pt_interrupt();
 	}
 
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index bf0a9ce53750..112ffb355552 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1893,7 +1893,7 @@ int kvm_skip_emulated_instruction(struct kvm_vcpu *vcpu);
 int kvm_complete_insn_gp(struct kvm_vcpu *vcpu, int err);
 void __kvm_request_immediate_exit(struct kvm_vcpu *vcpu);
 
-int kvm_is_in_guest(void);
+unsigned int kvm_guest_state(void);
 
 void __user *__x86_set_memory_region(struct kvm *kvm, int id, gpa_t gpa,
 				     u32 size);
diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index 0772bad9165c..5b68d4188de0 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -87,7 +87,7 @@ static void kvm_perf_overflow_intr(struct perf_event *perf_event,
 		 * woken up. So we should wake it, but this is impossible from
 		 * NMI context. Do it from irq work instead.
 		 */
-		if (!kvm_is_in_guest())
+		if (!kvm_guest_state())
 			irq_work_queue(&pmc_to_pmu(pmc)->irq_work);
 		else
 			kvm_make_request(KVM_REQ_PMI, pmc->vcpu);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 021d3f5364b2..ceb09d78277e 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8413,44 +8413,48 @@ static void kvm_timer_init(void)
 DEFINE_PER_CPU(struct kvm_vcpu *, current_vcpu);
 EXPORT_PER_CPU_SYMBOL_GPL(current_vcpu);
 
-int kvm_is_in_guest(void)
+unsigned int kvm_guest_state(void)
 {
-	return __this_cpu_read(current_vcpu) != NULL;
-}
+	struct kvm_vcpu *vcpu = __this_cpu_read(current_vcpu);
+	unsigned int state;
 
-static int kvm_is_user_mode(void)
-{
-	int user_mode = 3;
+	if (!vcpu)
+		return 0;
 
-	if (__this_cpu_read(current_vcpu))
-		user_mode = static_call(kvm_x86_get_cpl)(__this_cpu_read(current_vcpu));
+	state = PERF_GUEST_ACTIVE;
+	if (static_call(kvm_x86_get_cpl)(vcpu))
+		state |= PERF_GUEST_USER;
 
-	return user_mode != 0;
+	return state;
 }
 
-static unsigned long kvm_get_guest_ip(void)
+static unsigned long kvm_guest_get_ip(void)
 {
-	unsigned long ip = 0;
+	struct kvm_vcpu *vcpu = __this_cpu_read(current_vcpu);
 
-	if (__this_cpu_read(current_vcpu))
-		ip = kvm_rip_read(__this_cpu_read(current_vcpu));
+	if (WARN_ON_ONCE(!vcpu))
+		return 0;
 
-	return ip;
+	return kvm_rip_read(vcpu);
 }
 
-static void kvm_handle_intel_pt_intr(void)
+static unsigned int kvm_handle_intel_pt_intr(void)
 {
 	struct kvm_vcpu *vcpu = __this_cpu_read(current_vcpu);
 
+	/* '0' on failure so that the !PT case can use a RET0 static call. */
+	if (!vcpu)
+		return 0;
+
 	kvm_make_request(KVM_REQ_PMI, vcpu);
 	__set_bit(MSR_CORE_PERF_GLOBAL_OVF_CTRL_TRACE_TOPA_PMI_BIT,
 			(unsigned long *)&vcpu->arch.pmu.global_status);
+	return 1;
 }
 
 static struct perf_guest_info_callbacks kvm_guest_cbs = {
-	.is_in_guest		= kvm_is_in_guest,
-	.is_user_mode		= kvm_is_user_mode,
-	.get_guest_ip		= kvm_get_guest_ip,
+	.state			= kvm_guest_state,
+	.get_ip			= kvm_guest_get_ip,
 	.handle_intel_pt_intr	= NULL,
 };
 
diff --git a/arch/x86/xen/pmu.c b/arch/x86/xen/pmu.c
index e13b0b49fcdf..89dd6b1708b0 100644
--- a/arch/x86/xen/pmu.c
+++ b/arch/x86/xen/pmu.c
@@ -413,34 +413,29 @@ int pmu_apic_update(uint32_t val)
 }
 
 /* perf callbacks */
-static int xen_is_in_guest(void)
+static unsigned int xen_guest_state(void)
 {
 	const struct xen_pmu_data *xenpmu_data = get_xenpmu_data();
+	unsigned int state = 0;
 
 	if (!xenpmu_data) {
 		pr_warn_once("%s: pmudata not initialized\n", __func__);
-		return 0;
+		return state;
 	}
 
 	if (!xen_initial_domain() || (xenpmu_data->domain_id >= DOMID_SELF))
-		return 0;
+		return state;
 
-	return 1;
-}
+	state |= PERF_GUEST_ACTIVE;
 
-static int xen_is_user_mode(void)
-{
-	const struct xen_pmu_data *xenpmu_data = get_xenpmu_data();
-
-	if (!xenpmu_data) {
-		pr_warn_once("%s: pmudata not initialized\n", __func__);
-		return 0;
+	if (xenpmu_data->pmu.pmu_flags & PMU_SAMPLE_PV) {
+		if (xenpmu_data->pmu.pmu_flags & PMU_SAMPLE_USER)
+			state |= PERF_GUEST_USER;
+	} else if (xenpmu_data->pmu.r.regs.cpl & 3) {
+		state |= PERF_GUEST_USER;
 	}
 
-	if (xenpmu_data->pmu.pmu_flags & PMU_SAMPLE_PV)
-		return (xenpmu_data->pmu.pmu_flags & PMU_SAMPLE_USER);
-	else
-		return !!(xenpmu_data->pmu.r.regs.cpl & 3);
+	return state;
 }
 
 static unsigned long xen_get_guest_ip(void)
@@ -456,9 +451,8 @@ static unsigned long xen_get_guest_ip(void)
 }
 
 static struct perf_guest_info_callbacks xen_guest_cbs = {
-	.is_in_guest            = xen_is_in_guest,
-	.is_user_mode           = xen_is_user_mode,
-	.get_guest_ip           = xen_get_guest_ip,
+	.state                  = xen_guest_state,
+	.get_ip			= xen_get_guest_ip,
 };
 
 /* Convert registers from Xen's format to Linux' */
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 98c204488496..5e6b346d62a7 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -26,11 +26,13 @@
 # include <asm/local64.h>
 #endif
 
+#define PERF_GUEST_ACTIVE	0x01
+#define PERF_GUEST_USER	0x02
+
 struct perf_guest_info_callbacks {
-	int				(*is_in_guest)(void);
-	int				(*is_user_mode)(void);
-	unsigned long			(*get_guest_ip)(void);
-	void				(*handle_intel_pt_intr)(void);
+	unsigned int			(*state)(void);
+	unsigned long			(*get_ip)(void);
+	unsigned int			(*handle_intel_pt_intr)(void);
 };
 
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
-- 
2.34.0.rc0.344.g81b53c2807-goog

[tip: perf/core] perf/core: Rework guest callbacks to prepare for static_call support

[tip-bot2 for Like Xu]

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     b9f5621c9547dd787900f005a9e1c3d5712de512
Gitweb:        https://git.kernel.org/tip/b9f5621c9547dd787900f005a9e1c3d5712de512
Author:        Like Xu <like.xu@linux.intel.com>
AuthorDate:    Thu, 11 Nov 2021 02:07:27 
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Wed, 17 Nov 2021 14:49:07 +01:00

perf/core: Rework guest callbacks to prepare for static_call support

To prepare for using static_calls to optimize perf's guest callbacks,
replace ->is_in_guest and ->is_user_mode with a new multiplexed hook
->state, tweak ->handle_intel_pt_intr to play nice with being called when
there is no active guest, and drop "guest" from ->get_guest_ip.

Return '0' from ->state and ->handle_intel_pt_intr to indicate "not in
guest" so that DEFINE_STATIC_CALL_RET0 can be used to define the static
calls, i.e. no callback == !guest.

[sean: extracted from static_call patch, fixed get_ip() bug, wrote changelog]
Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Originally-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Like Xu <like.xu@linux.intel.com>
Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Link: https://lore.kernel.org/r/20211111020738.2512932-7-seanjc@google.com
---
 arch/arm64/kernel/perf_callchain.c | 13 ++++-----
 arch/arm64/kvm/perf.c              | 35 ++++++++++---------------
 arch/x86/events/core.c             | 13 ++++-----
 arch/x86/events/intel/core.c       |  5 +----
 arch/x86/include/asm/kvm_host.h    |  2 +-
 arch/x86/kvm/pmu.c                 |  2 +-
 arch/x86/kvm/x86.c                 | 40 +++++++++++++++--------------
 arch/x86/xen/pmu.c                 | 32 +++++++++--------------
 include/linux/perf_event.h         | 10 ++++---
 9 files changed, 73 insertions(+), 79 deletions(-)

diff --git a/arch/arm64/kernel/perf_callchain.c b/arch/arm64/kernel/perf_callchain.c
index 86d9f20..274dc3e 100644
--- a/arch/arm64/kernel/perf_callchain.c
+++ b/arch/arm64/kernel/perf_callchain.c
@@ -104,7 +104,7 @@ void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
 {
 	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 
-	if (guest_cbs && guest_cbs->is_in_guest()) {
+	if (guest_cbs && guest_cbs->state()) {
 		/* We don't support guest os callchain now */
 		return;
 	}
@@ -152,7 +152,7 @@ void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
 	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	struct stackframe frame;
 
-	if (guest_cbs && guest_cbs->is_in_guest()) {
+	if (guest_cbs && guest_cbs->state()) {
 		/* We don't support guest os callchain now */
 		return;
 	}
@@ -165,8 +165,8 @@ unsigned long perf_instruction_pointer(struct pt_regs *regs)
 {
 	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 
-	if (guest_cbs && guest_cbs->is_in_guest())
-		return guest_cbs->get_guest_ip();
+	if (guest_cbs && guest_cbs->state())
+		return guest_cbs->get_ip();
 
 	return instruction_pointer(regs);
 }
@@ -174,10 +174,11 @@ unsigned long perf_instruction_pointer(struct pt_regs *regs)
 unsigned long perf_misc_flags(struct pt_regs *regs)
 {
 	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
+	unsigned int guest_state = guest_cbs ? guest_cbs->state() : 0;
 	int misc = 0;
 
-	if (guest_cbs && guest_cbs->is_in_guest()) {
-		if (guest_cbs->is_user_mode())
+	if (guest_state) {
+		if (guest_state & PERF_GUEST_USER)
 			misc |= PERF_RECORD_MISC_GUEST_USER;
 		else
 			misc |= PERF_RECORD_MISC_GUEST_KERNEL;
diff --git a/arch/arm64/kvm/perf.c b/arch/arm64/kvm/perf.c
index a0d660c..dfa9bce 100644
--- a/arch/arm64/kvm/perf.c
+++ b/arch/arm64/kvm/perf.c
@@ -13,39 +13,34 @@
 
 DEFINE_STATIC_KEY_FALSE(kvm_arm_pmu_available);
 
-static int kvm_is_in_guest(void)
+static unsigned int kvm_guest_state(void)
 {
-        return kvm_get_running_vcpu() != NULL;
-}
-
-static int kvm_is_user_mode(void)
-{
-	struct kvm_vcpu *vcpu;
+	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
+	unsigned int state;
 
-	vcpu = kvm_get_running_vcpu();
+	if (!vcpu)
+		return 0;
 
-	if (vcpu)
-		return !vcpu_mode_priv(vcpu);
+	state = PERF_GUEST_ACTIVE;
+	if (!vcpu_mode_priv(vcpu))
+		state |= PERF_GUEST_USER;
 
-	return 0;
+	return state;
 }
 
 static unsigned long kvm_get_guest_ip(void)
 {
-	struct kvm_vcpu *vcpu;
-
-	vcpu = kvm_get_running_vcpu();
+	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
 
-	if (vcpu)
-		return *vcpu_pc(vcpu);
+	if (WARN_ON_ONCE(!vcpu))
+		return 0;
 
-	return 0;
+	return *vcpu_pc(vcpu);
 }
 
 static struct perf_guest_info_callbacks kvm_guest_cbs = {
-	.is_in_guest	= kvm_is_in_guest,
-	.is_user_mode	= kvm_is_user_mode,
-	.get_guest_ip	= kvm_get_guest_ip,
+	.state		= kvm_guest_state,
+	.get_ip		= kvm_get_guest_ip,
 };
 
 void kvm_perf_init(void)
diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 32cec29..e29312a 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -2772,7 +2772,7 @@ perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *re
 	struct unwind_state state;
 	unsigned long addr;
 
-	if (guest_cbs && guest_cbs->is_in_guest()) {
+	if (guest_cbs && guest_cbs->state()) {
 		/* TODO: We don't support guest os callchain now */
 		return;
 	}
@@ -2876,7 +2876,7 @@ perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs
 	struct stack_frame frame;
 	const struct stack_frame __user *fp;
 
-	if (guest_cbs && guest_cbs->is_in_guest()) {
+	if (guest_cbs && guest_cbs->state()) {
 		/* TODO: We don't support guest os callchain now */
 		return;
 	}
@@ -2955,8 +2955,8 @@ unsigned long perf_instruction_pointer(struct pt_regs *regs)
 {
 	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 
-	if (guest_cbs && guest_cbs->is_in_guest())
-		return guest_cbs->get_guest_ip();
+	if (guest_cbs && guest_cbs->state())
+		return guest_cbs->get_ip();
 
 	return regs->ip + code_segment_base(regs);
 }
@@ -2964,10 +2964,11 @@ unsigned long perf_instruction_pointer(struct pt_regs *regs)
 unsigned long perf_misc_flags(struct pt_regs *regs)
 {
 	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
+	unsigned int guest_state = guest_cbs ? guest_cbs->state() : 0;
 	int misc = 0;
 
-	if (guest_cbs && guest_cbs->is_in_guest()) {
-		if (guest_cbs->is_user_mode())
+	if (guest_state) {
+		if (guest_state & PERF_GUEST_USER)
 			misc |= PERF_RECORD_MISC_GUEST_USER;
 		else
 			misc |= PERF_RECORD_MISC_GUEST_KERNEL;
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 2258e02..7ff24d1 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -2906,10 +2906,7 @@ static int handle_pmi_common(struct pt_regs *regs, u64 status)
 		handled++;
 
 		guest_cbs = perf_get_guest_cbs();
-		if (unlikely(guest_cbs && guest_cbs->is_in_guest() &&
-			     guest_cbs->handle_intel_pt_intr))
-			guest_cbs->handle_intel_pt_intr();
-		else
+		if (likely(!guest_cbs || !guest_cbs->handle_intel_pt_intr()))
 			intel_pt_interrupt();
 	}
 
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 41e858d..fa1b1a2 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1895,7 +1895,7 @@ int kvm_skip_emulated_instruction(struct kvm_vcpu *vcpu);
 int kvm_complete_insn_gp(struct kvm_vcpu *vcpu, int err);
 void __kvm_request_immediate_exit(struct kvm_vcpu *vcpu);
 
-int kvm_is_in_guest(void);
+unsigned int kvm_guest_state(void);
 
 void __user *__x86_set_memory_region(struct kvm *kvm, int id, gpa_t gpa,
 				     u32 size);
diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index 09873f6..b2520b3 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -87,7 +87,7 @@ static void kvm_perf_overflow_intr(struct perf_event *perf_event,
 		 * woken up. So we should wake it, but this is impossible from
 		 * NMI context. Do it from irq work instead.
 		 */
-		if (!kvm_is_in_guest())
+		if (!kvm_guest_state())
 			irq_work_queue(&pmc_to_pmu(pmc)->irq_work);
 		else
 			kvm_make_request(KVM_REQ_PMI, pmc->vcpu);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 760c4e3..2011a1c 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8472,44 +8472,48 @@ static void kvm_timer_init(void)
 DEFINE_PER_CPU(struct kvm_vcpu *, current_vcpu);
 EXPORT_PER_CPU_SYMBOL_GPL(current_vcpu);
 
-int kvm_is_in_guest(void)
+unsigned int kvm_guest_state(void)
 {
-	return __this_cpu_read(current_vcpu) != NULL;
-}
+	struct kvm_vcpu *vcpu = __this_cpu_read(current_vcpu);
+	unsigned int state;
 
-static int kvm_is_user_mode(void)
-{
-	int user_mode = 3;
+	if (!vcpu)
+		return 0;
 
-	if (__this_cpu_read(current_vcpu))
-		user_mode = static_call(kvm_x86_get_cpl)(__this_cpu_read(current_vcpu));
+	state = PERF_GUEST_ACTIVE;
+	if (static_call(kvm_x86_get_cpl)(vcpu))
+		state |= PERF_GUEST_USER;
 
-	return user_mode != 0;
+	return state;
 }
 
-static unsigned long kvm_get_guest_ip(void)
+static unsigned long kvm_guest_get_ip(void)
 {
-	unsigned long ip = 0;
+	struct kvm_vcpu *vcpu = __this_cpu_read(current_vcpu);
 
-	if (__this_cpu_read(current_vcpu))
-		ip = kvm_rip_read(__this_cpu_read(current_vcpu));
+	if (WARN_ON_ONCE(!vcpu))
+		return 0;
 
-	return ip;
+	return kvm_rip_read(vcpu);
 }
 
-static void kvm_handle_intel_pt_intr(void)
+static unsigned int kvm_handle_intel_pt_intr(void)
 {
 	struct kvm_vcpu *vcpu = __this_cpu_read(current_vcpu);
 
+	/* '0' on failure so that the !PT case can use a RET0 static call. */
+	if (!vcpu)
+		return 0;
+
 	kvm_make_request(KVM_REQ_PMI, vcpu);
 	__set_bit(MSR_CORE_PERF_GLOBAL_OVF_CTRL_TRACE_TOPA_PMI_BIT,
 			(unsigned long *)&vcpu->arch.pmu.global_status);
+	return 1;
 }
 
 static struct perf_guest_info_callbacks kvm_guest_cbs = {
-	.is_in_guest		= kvm_is_in_guest,
-	.is_user_mode		= kvm_is_user_mode,
-	.get_guest_ip		= kvm_get_guest_ip,
+	.state			= kvm_guest_state,
+	.get_ip			= kvm_guest_get_ip,
 	.handle_intel_pt_intr	= NULL,
 };
 
diff --git a/arch/x86/xen/pmu.c b/arch/x86/xen/pmu.c
index e13b0b4..89dd6b1 100644
--- a/arch/x86/xen/pmu.c
+++ b/arch/x86/xen/pmu.c
@@ -413,34 +413,29 @@ int pmu_apic_update(uint32_t val)
 }
 
 /* perf callbacks */
-static int xen_is_in_guest(void)
+static unsigned int xen_guest_state(void)
 {
 	const struct xen_pmu_data *xenpmu_data = get_xenpmu_data();
+	unsigned int state = 0;
 
 	if (!xenpmu_data) {
 		pr_warn_once("%s: pmudata not initialized\n", __func__);
-		return 0;
+		return state;
 	}
 
 	if (!xen_initial_domain() || (xenpmu_data->domain_id >= DOMID_SELF))
-		return 0;
+		return state;
 
-	return 1;
-}
-
-static int xen_is_user_mode(void)
-{
-	const struct xen_pmu_data *xenpmu_data = get_xenpmu_data();
+	state |= PERF_GUEST_ACTIVE;
 
-	if (!xenpmu_data) {
-		pr_warn_once("%s: pmudata not initialized\n", __func__);
-		return 0;
+	if (xenpmu_data->pmu.pmu_flags & PMU_SAMPLE_PV) {
+		if (xenpmu_data->pmu.pmu_flags & PMU_SAMPLE_USER)
+			state |= PERF_GUEST_USER;
+	} else if (xenpmu_data->pmu.r.regs.cpl & 3) {
+		state |= PERF_GUEST_USER;
 	}
 
-	if (xenpmu_data->pmu.pmu_flags & PMU_SAMPLE_PV)
-		return (xenpmu_data->pmu.pmu_flags & PMU_SAMPLE_USER);
-	else
-		return !!(xenpmu_data->pmu.r.regs.cpl & 3);
+	return state;
 }
 
 static unsigned long xen_get_guest_ip(void)
@@ -456,9 +451,8 @@ static unsigned long xen_get_guest_ip(void)
 }
 
 static struct perf_guest_info_callbacks xen_guest_cbs = {
-	.is_in_guest            = xen_is_in_guest,
-	.is_user_mode           = xen_is_user_mode,
-	.get_guest_ip           = xen_get_guest_ip,
+	.state                  = xen_guest_state,
+	.get_ip			= xen_get_guest_ip,
 };
 
 /* Convert registers from Xen's format to Linux' */
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 98c2044..5e6b346 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -26,11 +26,13 @@
 # include <asm/local64.h>
 #endif
 
+#define PERF_GUEST_ACTIVE	0x01
+#define PERF_GUEST_USER	0x02
+
 struct perf_guest_info_callbacks {
-	int				(*is_in_guest)(void);
-	int				(*is_user_mode)(void);
-	unsigned long			(*get_guest_ip)(void);
-	void				(*handle_intel_pt_intr)(void);
+	unsigned int			(*state)(void);
+	unsigned long			(*get_ip)(void);
+	unsigned int			(*handle_intel_pt_intr)(void);
 };
 
 #ifdef CONFIG_HAVE_HW_BREAKPOINT

[PATCH v4 07/17] perf: Add wrappers for invoking guest callbacks

[Sean Christopherson]

Add helpers for the guest callbacks to prepare for burying the callbacks
behind a Kconfig (it's a lot easier to provide a few stubs than to #ifdef
piles of code), and also to prepare for converting the callbacks to
static_call().  perf_instruction_pointer() in particular will have subtle
semantics with static_call(), as the "no callbacks" case will return 0 if
the callbacks are unregistered between querying guest state and getting
the IP.  Implement the change now to avoid a functional change when adding
static_call() support, and because the new helper needs to return
_something_ in this case.

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/arm64/kernel/perf_callchain.c | 16 +++++-----------
 arch/x86/events/core.c             | 15 +++++----------
 arch/x86/events/intel/core.c       |  5 +----
 include/linux/perf_event.h         | 24 ++++++++++++++++++++++++
 4 files changed, 35 insertions(+), 25 deletions(-)

diff --git a/arch/arm64/kernel/perf_callchain.c b/arch/arm64/kernel/perf_callchain.c
index 274dc3e11b6d..db04a55cee7e 100644
--- a/arch/arm64/kernel/perf_callchain.c
+++ b/arch/arm64/kernel/perf_callchain.c
@@ -102,9 +102,7 @@ compat_user_backtrace(struct compat_frame_tail __user *tail,
 void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
 			 struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
-
-	if (guest_cbs && guest_cbs->state()) {
+	if (perf_guest_state()) {
 		/* We don't support guest os callchain now */
 		return;
 	}
@@ -149,10 +147,9 @@ static bool callchain_trace(void *data, unsigned long pc)
 void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
 			   struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	struct stackframe frame;
 
-	if (guest_cbs && guest_cbs->state()) {
+	if (perf_guest_state()) {
 		/* We don't support guest os callchain now */
 		return;
 	}
@@ -163,18 +160,15 @@ void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
 
 unsigned long perf_instruction_pointer(struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
-
-	if (guest_cbs && guest_cbs->state())
-		return guest_cbs->get_ip();
+	if (perf_guest_state())
+		return perf_guest_get_ip();
 
 	return instruction_pointer(regs);
 }
 
 unsigned long perf_misc_flags(struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
-	unsigned int guest_state = guest_cbs ? guest_cbs->state() : 0;
+	unsigned int guest_state = perf_guest_state();
 	int misc = 0;
 
 	if (guest_state) {
diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index e29312a1003a..620347398027 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -2768,11 +2768,10 @@ static bool perf_hw_regs(struct pt_regs *regs)
 void
 perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	struct unwind_state state;
 	unsigned long addr;
 
-	if (guest_cbs && guest_cbs->state()) {
+	if (perf_guest_state()) {
 		/* TODO: We don't support guest os callchain now */
 		return;
 	}
@@ -2872,11 +2871,10 @@ perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry_ctx *ent
 void
 perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	struct stack_frame frame;
 	const struct stack_frame __user *fp;
 
-	if (guest_cbs && guest_cbs->state()) {
+	if (perf_guest_state()) {
 		/* TODO: We don't support guest os callchain now */
 		return;
 	}
@@ -2953,18 +2951,15 @@ static unsigned long code_segment_base(struct pt_regs *regs)
 
 unsigned long perf_instruction_pointer(struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
-
-	if (guest_cbs && guest_cbs->state())
-		return guest_cbs->get_ip();
+	if (perf_guest_state())
+		return perf_guest_get_ip();
 
 	return regs->ip + code_segment_base(regs);
 }
 
 unsigned long perf_misc_flags(struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
-	unsigned int guest_state = guest_cbs ? guest_cbs->state() : 0;
+	unsigned int guest_state = perf_guest_state();
 	int misc = 0;
 
 	if (guest_state) {
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 24adbd6282d4..a5fb247a6a27 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -2837,7 +2837,6 @@ static int handle_pmi_common(struct pt_regs *regs, u64 status)
 {
 	struct perf_sample_data data;
 	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
-	struct perf_guest_info_callbacks *guest_cbs;
 	int bit;
 	int handled = 0;
 	u64 intel_ctrl = hybrid(cpuc->pmu, intel_ctrl);
@@ -2904,9 +2903,7 @@ static int handle_pmi_common(struct pt_regs *regs, u64 status)
 	 */
 	if (__test_and_clear_bit(GLOBAL_STATUS_TRACE_TOPAPMI_BIT, (unsigned long *)&status)) {
 		handled++;
-
-		guest_cbs = perf_get_guest_cbs();
-		if (likely(!guest_cbs || !guest_cbs->handle_intel_pt_intr()))
+		if (!perf_guest_handle_intel_pt_intr())
 			intel_pt_interrupt();
 	}
 
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 5e6b346d62a7..346d5aff5804 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1254,6 +1254,30 @@ static inline struct perf_guest_info_callbacks *perf_get_guest_cbs(void)
 	 */
 	return rcu_dereference(perf_guest_cbs);
 }
+static inline unsigned int perf_guest_state(void)
+{
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
+
+	return guest_cbs ? guest_cbs->state() : 0;
+}
+static inline unsigned long perf_guest_get_ip(void)
+{
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
+
+	/*
+	 * Arbitrarily return '0' in the unlikely scenario that the callbacks
+	 * are unregistered between checking guest state and getting the IP.
+	 */
+	return guest_cbs ? guest_cbs->get_ip() : 0;
+}
+static inline unsigned int perf_guest_handle_intel_pt_intr(void)
+{
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
+
+	if (guest_cbs && guest_cbs->handle_intel_pt_intr)
+		return guest_cbs->handle_intel_pt_intr();
+	return 0;
+}
 extern void perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs);
 extern void perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs);
 
-- 
2.34.0.rc0.344.g81b53c2807-goog

[tip: perf/core] perf: Add wrappers for invoking guest callbacks

[tip-bot2 for Sean Christopherson]

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     1c3430516b0732d923de9fd3bfb3e2e537eeb235
Gitweb:        https://git.kernel.org/tip/1c3430516b0732d923de9fd3bfb3e2e537eeb235
Author:        Sean Christopherson <seanjc@google.com>
AuthorDate:    Thu, 11 Nov 2021 02:07:28 
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Wed, 17 Nov 2021 14:49:08 +01:00

perf: Add wrappers for invoking guest callbacks

Add helpers for the guest callbacks to prepare for burying the callbacks
behind a Kconfig (it's a lot easier to provide a few stubs than to #ifdef
piles of code), and also to prepare for converting the callbacks to
static_call().  perf_instruction_pointer() in particular will have subtle
semantics with static_call(), as the "no callbacks" case will return 0 if
the callbacks are unregistered between querying guest state and getting
the IP.  Implement the change now to avoid a functional change when adding
static_call() support, and because the new helper needs to return
_something_ in this case.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Link: https://lore.kernel.org/r/20211111020738.2512932-8-seanjc@google.com
---
 arch/arm64/kernel/perf_callchain.c | 16 +++++-----------
 arch/x86/events/core.c             | 15 +++++----------
 arch/x86/events/intel/core.c       |  5 +----
 include/linux/perf_event.h         | 24 ++++++++++++++++++++++++
 4 files changed, 35 insertions(+), 25 deletions(-)

diff --git a/arch/arm64/kernel/perf_callchain.c b/arch/arm64/kernel/perf_callchain.c
index 274dc3e..db04a55 100644
--- a/arch/arm64/kernel/perf_callchain.c
+++ b/arch/arm64/kernel/perf_callchain.c
@@ -102,9 +102,7 @@ compat_user_backtrace(struct compat_frame_tail __user *tail,
 void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
 			 struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
-
-	if (guest_cbs && guest_cbs->state()) {
+	if (perf_guest_state()) {
 		/* We don't support guest os callchain now */
 		return;
 	}
@@ -149,10 +147,9 @@ static bool callchain_trace(void *data, unsigned long pc)
 void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
 			   struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	struct stackframe frame;
 
-	if (guest_cbs && guest_cbs->state()) {
+	if (perf_guest_state()) {
 		/* We don't support guest os callchain now */
 		return;
 	}
@@ -163,18 +160,15 @@ void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
 
 unsigned long perf_instruction_pointer(struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
-
-	if (guest_cbs && guest_cbs->state())
-		return guest_cbs->get_ip();
+	if (perf_guest_state())
+		return perf_guest_get_ip();
 
 	return instruction_pointer(regs);
 }
 
 unsigned long perf_misc_flags(struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
-	unsigned int guest_state = guest_cbs ? guest_cbs->state() : 0;
+	unsigned int guest_state = perf_guest_state();
 	int misc = 0;
 
 	if (guest_state) {
diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index e29312a..6203473 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -2768,11 +2768,10 @@ static bool perf_hw_regs(struct pt_regs *regs)
 void
 perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	struct unwind_state state;
 	unsigned long addr;
 
-	if (guest_cbs && guest_cbs->state()) {
+	if (perf_guest_state()) {
 		/* TODO: We don't support guest os callchain now */
 		return;
 	}
@@ -2872,11 +2871,10 @@ perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry_ctx *ent
 void
 perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
 	struct stack_frame frame;
 	const struct stack_frame __user *fp;
 
-	if (guest_cbs && guest_cbs->state()) {
+	if (perf_guest_state()) {
 		/* TODO: We don't support guest os callchain now */
 		return;
 	}
@@ -2953,18 +2951,15 @@ static unsigned long code_segment_base(struct pt_regs *regs)
 
 unsigned long perf_instruction_pointer(struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
-
-	if (guest_cbs && guest_cbs->state())
-		return guest_cbs->get_ip();
+	if (perf_guest_state())
+		return perf_guest_get_ip();
 
 	return regs->ip + code_segment_base(regs);
 }
 
 unsigned long perf_misc_flags(struct pt_regs *regs)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
-	unsigned int guest_state = guest_cbs ? guest_cbs->state() : 0;
+	unsigned int guest_state = perf_guest_state();
 	int misc = 0;
 
 	if (guest_state) {
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 7ff24d1..f7af802 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -2837,7 +2837,6 @@ static int handle_pmi_common(struct pt_regs *regs, u64 status)
 {
 	struct perf_sample_data data;
 	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
-	struct perf_guest_info_callbacks *guest_cbs;
 	int bit;
 	int handled = 0;
 	u64 intel_ctrl = hybrid(cpuc->pmu, intel_ctrl);
@@ -2904,9 +2903,7 @@ static int handle_pmi_common(struct pt_regs *regs, u64 status)
 	 */
 	if (__test_and_clear_bit(GLOBAL_STATUS_TRACE_TOPAPMI_BIT, (unsigned long *)&status)) {
 		handled++;
-
-		guest_cbs = perf_get_guest_cbs();
-		if (likely(!guest_cbs || !guest_cbs->handle_intel_pt_intr()))
+		if (!perf_guest_handle_intel_pt_intr())
 			intel_pt_interrupt();
 	}
 
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 5e6b346..346d5af 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1254,6 +1254,30 @@ static inline struct perf_guest_info_callbacks *perf_get_guest_cbs(void)
 	 */
 	return rcu_dereference(perf_guest_cbs);
 }
+static inline unsigned int perf_guest_state(void)
+{
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
+
+	return guest_cbs ? guest_cbs->state() : 0;
+}
+static inline unsigned long perf_guest_get_ip(void)
+{
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
+
+	/*
+	 * Arbitrarily return '0' in the unlikely scenario that the callbacks
+	 * are unregistered between checking guest state and getting the IP.
+	 */
+	return guest_cbs ? guest_cbs->get_ip() : 0;
+}
+static inline unsigned int perf_guest_handle_intel_pt_intr(void)
+{
+	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
+
+	if (guest_cbs && guest_cbs->handle_intel_pt_intr)
+		return guest_cbs->handle_intel_pt_intr();
+	return 0;
+}
 extern void perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs);
 extern void perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs);
 

[PATCH v4 08/17] perf: Force architectures to opt-in to guest callbacks

[Sean Christopherson]

Introduce GUEST_PERF_EVENTS and require architectures to select it to
allow registering and using guest callbacks in perf.  This will hopefully
make it more difficult for new architectures to add useless "support" for
guest callbacks, e.g. via copy+paste.

Stubbing out the helpers has the happy bonus of avoiding a load of
perf_guest_cbs when GUEST_PERF_EVENTS=n on arm64/x86.

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/arm64/kvm/Kconfig     | 1 +
 arch/x86/kvm/Kconfig       | 1 +
 arch/x86/xen/Kconfig       | 1 +
 include/linux/perf_event.h | 6 ++++++
 init/Kconfig               | 4 ++++
 kernel/events/core.c       | 2 ++
 6 files changed, 15 insertions(+)

diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
index 8ffcbe29395e..e9761d84f982 100644
--- a/arch/arm64/kvm/Kconfig
+++ b/arch/arm64/kvm/Kconfig
@@ -39,6 +39,7 @@ menuconfig KVM
 	select HAVE_KVM_IRQ_BYPASS
 	select HAVE_KVM_VCPU_RUN_PID_CHANGE
 	select SCHED_INFO
+	select GUEST_PERF_EVENTS if PERF_EVENTS
 	help
 	  Support hosting virtualized guest machines.
 
diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
index 619186138176..47bdbe705a76 100644
--- a/arch/x86/kvm/Kconfig
+++ b/arch/x86/kvm/Kconfig
@@ -36,6 +36,7 @@ config KVM
 	select KVM_MMIO
 	select SCHED_INFO
 	select PERF_EVENTS
+	select GUEST_PERF_EVENTS
 	select HAVE_KVM_MSI
 	select HAVE_KVM_CPU_RELAX_INTERCEPT
 	select HAVE_KVM_NO_POLL
diff --git a/arch/x86/xen/Kconfig b/arch/x86/xen/Kconfig
index 6bcd3d8ca6ac..85246dd9faa1 100644
--- a/arch/x86/xen/Kconfig
+++ b/arch/x86/xen/Kconfig
@@ -23,6 +23,7 @@ config XEN_PV
 	select PARAVIRT_XXL
 	select XEN_HAVE_PVMMU
 	select XEN_HAVE_VPMU
+	select GUEST_PERF_EVENTS
 	help
 	  Support running as a Xen PV guest.
 
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 346d5aff5804..ea47ef616ee0 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1242,6 +1242,7 @@ extern void perf_event_bpf_event(struct bpf_prog *prog,
 				 enum perf_bpf_event_type type,
 				 u16 flags);
 
+#ifdef CONFIG_GUEST_PERF_EVENTS
 extern struct perf_guest_info_callbacks __rcu *perf_guest_cbs;
 static inline struct perf_guest_info_callbacks *perf_get_guest_cbs(void)
 {
@@ -1280,6 +1281,11 @@ static inline unsigned int perf_guest_handle_intel_pt_intr(void)
 }
 extern void perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs);
 extern void perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs);
+#else
+static inline unsigned int perf_guest_state(void)		 { return 0; }
+static inline unsigned long perf_guest_get_ip(void)		 { return 0; }
+static inline unsigned int perf_guest_handle_intel_pt_intr(void) { return 0; }
+#endif /* CONFIG_GUEST_PERF_EVENTS */
 
 extern void perf_event_exec(void);
 extern void perf_event_comm(struct task_struct *tsk, bool exec);
diff --git a/init/Kconfig b/init/Kconfig
index 21b1f4870c80..6bc5c56d669b 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1799,6 +1799,10 @@ config HAVE_PERF_EVENTS
 	help
 	  See tools/perf/design.txt for details.
 
+config GUEST_PERF_EVENTS
+	bool
+	depends on HAVE_PERF_EVENTS
+
 config PERF_USE_VMALLOC
 	bool
 	help
diff --git a/kernel/events/core.c b/kernel/events/core.c
index eb6b9cfd0054..1c8d341ecc77 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6521,6 +6521,7 @@ static void perf_pending_event(struct irq_work *entry)
 		perf_swevent_put_recursion_context(rctx);
 }
 
+#ifdef CONFIG_GUEST_PERF_EVENTS
 struct perf_guest_info_callbacks __rcu *perf_guest_cbs;
 
 void perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
@@ -6541,6 +6542,7 @@ void perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
 	synchronize_rcu();
 }
 EXPORT_SYMBOL_GPL(perf_unregister_guest_info_callbacks);
+#endif
 
 static void
 perf_output_sample_regs(struct perf_output_handle *handle,
-- 
2.34.0.rc0.344.g81b53c2807-goog

[tip: perf/core] perf: Force architectures to opt-in to guest callbacks

[tip-bot2 for Sean Christopherson]

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     2aef6f306b39bbe74e2287d6e2ee07c4867d87d0
Gitweb:        https://git.kernel.org/tip/2aef6f306b39bbe74e2287d6e2ee07c4867d87d0
Author:        Sean Christopherson <seanjc@google.com>
AuthorDate:    Thu, 11 Nov 2021 02:07:29 
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Wed, 17 Nov 2021 14:49:08 +01:00

perf: Force architectures to opt-in to guest callbacks

Introduce GUEST_PERF_EVENTS and require architectures to select it to
allow registering and using guest callbacks in perf.  This will hopefully
make it more difficult for new architectures to add useless "support" for
guest callbacks, e.g. via copy+paste.

Stubbing out the helpers has the happy bonus of avoiding a load of
perf_guest_cbs when GUEST_PERF_EVENTS=n on arm64/x86.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Link: https://lore.kernel.org/r/20211111020738.2512932-9-seanjc@google.com
---
 arch/arm64/kvm/Kconfig     | 1 +
 arch/x86/kvm/Kconfig       | 1 +
 arch/x86/xen/Kconfig       | 1 +
 include/linux/perf_event.h | 6 ++++++
 init/Kconfig               | 4 ++++
 kernel/events/core.c       | 2 ++
 6 files changed, 15 insertions(+)

diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
index 8ffcbe2..e9761d8 100644
--- a/arch/arm64/kvm/Kconfig
+++ b/arch/arm64/kvm/Kconfig
@@ -39,6 +39,7 @@ menuconfig KVM
 	select HAVE_KVM_IRQ_BYPASS
 	select HAVE_KVM_VCPU_RUN_PID_CHANGE
 	select SCHED_INFO
+	select GUEST_PERF_EVENTS if PERF_EVENTS
 	help
 	  Support hosting virtualized guest machines.
 
diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
index 6191861..47bdbe7 100644
--- a/arch/x86/kvm/Kconfig
+++ b/arch/x86/kvm/Kconfig
@@ -36,6 +36,7 @@ config KVM
 	select KVM_MMIO
 	select SCHED_INFO
 	select PERF_EVENTS
+	select GUEST_PERF_EVENTS
 	select HAVE_KVM_MSI
 	select HAVE_KVM_CPU_RELAX_INTERCEPT
 	select HAVE_KVM_NO_POLL
diff --git a/arch/x86/xen/Kconfig b/arch/x86/xen/Kconfig
index 6bcd3d8..85246dd 100644
--- a/arch/x86/xen/Kconfig
+++ b/arch/x86/xen/Kconfig
@@ -23,6 +23,7 @@ config XEN_PV
 	select PARAVIRT_XXL
 	select XEN_HAVE_PVMMU
 	select XEN_HAVE_VPMU
+	select GUEST_PERF_EVENTS
 	help
 	  Support running as a Xen PV guest.
 
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 346d5af..ea47ef6 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1242,6 +1242,7 @@ extern void perf_event_bpf_event(struct bpf_prog *prog,
 				 enum perf_bpf_event_type type,
 				 u16 flags);
 
+#ifdef CONFIG_GUEST_PERF_EVENTS
 extern struct perf_guest_info_callbacks __rcu *perf_guest_cbs;
 static inline struct perf_guest_info_callbacks *perf_get_guest_cbs(void)
 {
@@ -1280,6 +1281,11 @@ static inline unsigned int perf_guest_handle_intel_pt_intr(void)
 }
 extern void perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs);
 extern void perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs);
+#else
+static inline unsigned int perf_guest_state(void)		 { return 0; }
+static inline unsigned long perf_guest_get_ip(void)		 { return 0; }
+static inline unsigned int perf_guest_handle_intel_pt_intr(void) { return 0; }
+#endif /* CONFIG_GUEST_PERF_EVENTS */
 
 extern void perf_event_exec(void);
 extern void perf_event_comm(struct task_struct *tsk, bool exec);
diff --git a/init/Kconfig b/init/Kconfig
index 036b750..72d40b3 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1804,6 +1804,10 @@ config HAVE_PERF_EVENTS
 	help
 	  See tools/perf/design.txt for details.
 
+config GUEST_PERF_EVENTS
+	bool
+	depends on HAVE_PERF_EVENTS
+
 config PERF_USE_VMALLOC
 	bool
 	help
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 17e5b20..5a3502c 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6521,6 +6521,7 @@ static void perf_pending_event(struct irq_work *entry)
 		perf_swevent_put_recursion_context(rctx);
 }
 
+#ifdef CONFIG_GUEST_PERF_EVENTS
 struct perf_guest_info_callbacks __rcu *perf_guest_cbs;
 
 void perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
@@ -6541,6 +6542,7 @@ void perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
 	synchronize_rcu();
 }
 EXPORT_SYMBOL_GPL(perf_unregister_guest_info_callbacks);
+#endif
 
 static void
 perf_output_sample_regs(struct perf_output_handle *handle,

[PATCH v4 09/17] perf/core: Use static_call to optimize perf_guest_info_callbacks

[Sean Christopherson]

Use static_call to optimize perf's guest callbacks on arm64 and x86,
which are now the only architectures that define the callbacks.  Use
DEFINE_STATIC_CALL_RET0 as the default/NULL for all guest callbacks, as
the callback semantics are that a return value '0' means "not in guest".

static_call obviously avoids the overhead of CONFIG_RETPOLINE=y, but is
also advantageous versus other solutions, e.g. per-cpu callbacks, in that
a per-cpu memory load is not needed to detect the !guest case.

Based on code from Peter and Like.

Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Like Xu <like.xu.linux@gmail.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 include/linux/perf_event.h | 34 ++++++++--------------------------
 kernel/events/core.c       | 15 +++++++++++++++
 2 files changed, 23 insertions(+), 26 deletions(-)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index ea47ef616ee0..0ac7d867ca0c 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1244,40 +1244,22 @@ extern void perf_event_bpf_event(struct bpf_prog *prog,
 
 #ifdef CONFIG_GUEST_PERF_EVENTS
 extern struct perf_guest_info_callbacks __rcu *perf_guest_cbs;
-static inline struct perf_guest_info_callbacks *perf_get_guest_cbs(void)
-{
-	/*
-	 * Callbacks are RCU-protected and must be READ_ONCE to avoid reloading
-	 * the callbacks between a !NULL check and dereferences, to ensure
-	 * pending stores/changes to the callback pointers are visible before a
-	 * non-NULL perf_guest_cbs is visible to readers, and to prevent a
-	 * module from unloading callbacks while readers are active.
-	 */
-	return rcu_dereference(perf_guest_cbs);
-}
+
+DECLARE_STATIC_CALL(__perf_guest_state, *perf_guest_cbs->state);
+DECLARE_STATIC_CALL(__perf_guest_get_ip, *perf_guest_cbs->get_ip);
+DECLARE_STATIC_CALL(__perf_guest_handle_intel_pt_intr, *perf_guest_cbs->handle_intel_pt_intr);
+
 static inline unsigned int perf_guest_state(void)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
-
-	return guest_cbs ? guest_cbs->state() : 0;
+	return static_call(__perf_guest_state)();
 }
 static inline unsigned long perf_guest_get_ip(void)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
-
-	/*
-	 * Arbitrarily return '0' in the unlikely scenario that the callbacks
-	 * are unregistered between checking guest state and getting the IP.
-	 */
-	return guest_cbs ? guest_cbs->get_ip() : 0;
+	return static_call(__perf_guest_get_ip)();
 }
 static inline unsigned int perf_guest_handle_intel_pt_intr(void)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
-
-	if (guest_cbs && guest_cbs->handle_intel_pt_intr)
-		return guest_cbs->handle_intel_pt_intr();
-	return 0;
+	return static_call(__perf_guest_handle_intel_pt_intr)();
 }
 extern void perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs);
 extern void perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs);
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 1c8d341ecc77..b4fd928e4ff8 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6524,12 +6524,23 @@ static void perf_pending_event(struct irq_work *entry)
 #ifdef CONFIG_GUEST_PERF_EVENTS
 struct perf_guest_info_callbacks __rcu *perf_guest_cbs;
 
+DEFINE_STATIC_CALL_RET0(__perf_guest_state, *perf_guest_cbs->state);
+DEFINE_STATIC_CALL_RET0(__perf_guest_get_ip, *perf_guest_cbs->get_ip);
+DEFINE_STATIC_CALL_RET0(__perf_guest_handle_intel_pt_intr, *perf_guest_cbs->handle_intel_pt_intr);
+
 void perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
 {
 	if (WARN_ON_ONCE(rcu_access_pointer(perf_guest_cbs)))
 		return;
 
 	rcu_assign_pointer(perf_guest_cbs, cbs);
+	static_call_update(__perf_guest_state, cbs->state);
+	static_call_update(__perf_guest_get_ip, cbs->get_ip);
+
+	/* Implementing ->handle_intel_pt_intr is optional. */
+	if (cbs->handle_intel_pt_intr)
+		static_call_update(__perf_guest_handle_intel_pt_intr,
+				   cbs->handle_intel_pt_intr);
 }
 EXPORT_SYMBOL_GPL(perf_register_guest_info_callbacks);
 
@@ -6539,6 +6550,10 @@ void perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
 		return;
 
 	rcu_assign_pointer(perf_guest_cbs, NULL);
+	static_call_update(__perf_guest_state, (void *)&__static_call_return0);
+	static_call_update(__perf_guest_get_ip, (void *)&__static_call_return0);
+	static_call_update(__perf_guest_handle_intel_pt_intr,
+			   (void *)&__static_call_return0);
 	synchronize_rcu();
 }
 EXPORT_SYMBOL_GPL(perf_unregister_guest_info_callbacks);
-- 
2.34.0.rc0.344.g81b53c2807-goog

[tip: perf/core] perf/core: Use static_call to optimize perf_guest_info_callbacks

[tip-bot2 for Sean Christopherson]

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     87b940a0675e25261f022ac3e53e0dfff9cdb995
Gitweb:        https://git.kernel.org/tip/87b940a0675e25261f022ac3e53e0dfff9cdb995
Author:        Sean Christopherson <seanjc@google.com>
AuthorDate:    Thu, 11 Nov 2021 02:07:30 
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Wed, 17 Nov 2021 14:49:09 +01:00

perf/core: Use static_call to optimize perf_guest_info_callbacks

Use static_call to optimize perf's guest callbacks on arm64 and x86,
which are now the only architectures that define the callbacks.  Use
DEFINE_STATIC_CALL_RET0 as the default/NULL for all guest callbacks, as
the callback semantics are that a return value '0' means "not in guest".

static_call obviously avoids the overhead of CONFIG_RETPOLINE=y, but is
also advantageous versus other solutions, e.g. per-cpu callbacks, in that
a per-cpu memory load is not needed to detect the !guest case.

Based on code from Peter and Like.

Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Link: https://lore.kernel.org/r/20211111020738.2512932-10-seanjc@google.com
---
 include/linux/perf_event.h | 34 ++++++++--------------------------
 kernel/events/core.c       | 15 +++++++++++++++
 2 files changed, 23 insertions(+), 26 deletions(-)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index ea47ef6..0ac7d86 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1244,40 +1244,22 @@ extern void perf_event_bpf_event(struct bpf_prog *prog,
 
 #ifdef CONFIG_GUEST_PERF_EVENTS
 extern struct perf_guest_info_callbacks __rcu *perf_guest_cbs;
-static inline struct perf_guest_info_callbacks *perf_get_guest_cbs(void)
-{
-	/*
-	 * Callbacks are RCU-protected and must be READ_ONCE to avoid reloading
-	 * the callbacks between a !NULL check and dereferences, to ensure
-	 * pending stores/changes to the callback pointers are visible before a
-	 * non-NULL perf_guest_cbs is visible to readers, and to prevent a
-	 * module from unloading callbacks while readers are active.
-	 */
-	return rcu_dereference(perf_guest_cbs);
-}
+
+DECLARE_STATIC_CALL(__perf_guest_state, *perf_guest_cbs->state);
+DECLARE_STATIC_CALL(__perf_guest_get_ip, *perf_guest_cbs->get_ip);
+DECLARE_STATIC_CALL(__perf_guest_handle_intel_pt_intr, *perf_guest_cbs->handle_intel_pt_intr);
+
 static inline unsigned int perf_guest_state(void)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
-
-	return guest_cbs ? guest_cbs->state() : 0;
+	return static_call(__perf_guest_state)();
 }
 static inline unsigned long perf_guest_get_ip(void)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
-
-	/*
-	 * Arbitrarily return '0' in the unlikely scenario that the callbacks
-	 * are unregistered between checking guest state and getting the IP.
-	 */
-	return guest_cbs ? guest_cbs->get_ip() : 0;
+	return static_call(__perf_guest_get_ip)();
 }
 static inline unsigned int perf_guest_handle_intel_pt_intr(void)
 {
-	struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
-
-	if (guest_cbs && guest_cbs->handle_intel_pt_intr)
-		return guest_cbs->handle_intel_pt_intr();
-	return 0;
+	return static_call(__perf_guest_handle_intel_pt_intr)();
 }
 extern void perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs);
 extern void perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs);
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 5a3502c..3b3297a 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6524,12 +6524,23 @@ static void perf_pending_event(struct irq_work *entry)
 #ifdef CONFIG_GUEST_PERF_EVENTS
 struct perf_guest_info_callbacks __rcu *perf_guest_cbs;
 
+DEFINE_STATIC_CALL_RET0(__perf_guest_state, *perf_guest_cbs->state);
+DEFINE_STATIC_CALL_RET0(__perf_guest_get_ip, *perf_guest_cbs->get_ip);
+DEFINE_STATIC_CALL_RET0(__perf_guest_handle_intel_pt_intr, *perf_guest_cbs->handle_intel_pt_intr);
+
 void perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
 {
 	if (WARN_ON_ONCE(rcu_access_pointer(perf_guest_cbs)))
 		return;
 
 	rcu_assign_pointer(perf_guest_cbs, cbs);
+	static_call_update(__perf_guest_state, cbs->state);
+	static_call_update(__perf_guest_get_ip, cbs->get_ip);
+
+	/* Implementing ->handle_intel_pt_intr is optional. */
+	if (cbs->handle_intel_pt_intr)
+		static_call_update(__perf_guest_handle_intel_pt_intr,
+				   cbs->handle_intel_pt_intr);
 }
 EXPORT_SYMBOL_GPL(perf_register_guest_info_callbacks);
 
@@ -6539,6 +6550,10 @@ void perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
 		return;
 
 	rcu_assign_pointer(perf_guest_cbs, NULL);
+	static_call_update(__perf_guest_state, (void *)&__static_call_return0);
+	static_call_update(__perf_guest_get_ip, (void *)&__static_call_return0);
+	static_call_update(__perf_guest_handle_intel_pt_intr,
+			   (void *)&__static_call_return0);
 	synchronize_rcu();
 }
 EXPORT_SYMBOL_GPL(perf_unregister_guest_info_callbacks);

Re: [PATCH v4 09/17] perf/core: Use static_call to optimize perf_guest_info_callbacks

[Sean Christopherson]

+Will and Sami, -most everyone else

On Thu, Nov 11, 2021, Sean Christopherson wrote:
> Use static_call to optimize perf's guest callbacks on arm64 and x86,
> which are now the only architectures that define the callbacks.  Use
> DEFINE_STATIC_CALL_RET0 as the default/NULL for all guest callbacks, as
> the callback semantics are that a return value '0' means "not in guest".
> 
> static_call obviously avoids the overhead of CONFIG_RETPOLINE=y, but is
> also advantageous versus other solutions, e.g. per-cpu callbacks, in that
> a per-cpu memory load is not needed to detect the !guest case.
> 
> Based on code from Peter and Like.
> 
> Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> Cc: Like Xu <like.xu.linux@gmail.com>
> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---

...

> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index 1c8d341ecc77..b4fd928e4ff8 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -6524,12 +6524,23 @@ static void perf_pending_event(struct irq_work *entry)
>  #ifdef CONFIG_GUEST_PERF_EVENTS
>  struct perf_guest_info_callbacks __rcu *perf_guest_cbs;
>  
> +DEFINE_STATIC_CALL_RET0(__perf_guest_state, *perf_guest_cbs->state);
> +DEFINE_STATIC_CALL_RET0(__perf_guest_get_ip, *perf_guest_cbs->get_ip);
> +DEFINE_STATIC_CALL_RET0(__perf_guest_handle_intel_pt_intr, *perf_guest_cbs->handle_intel_pt_intr);

Using __static_call_return0() makes clang's CFI sad on arm64 due to the resulting
function prototype mistmatch, which IIUC, is verified by clang's __cfi_check()
for indirect calls, i.e. architectures without CONFIG_HAVE_STATIC_CALL.

We could fudge around the issue by using stubs, massaging prototypes, etc..., but
that means doing that for every arch-agnostic user of __static_call_return0().

Any clever ideas?  Can we do something like generate a unique function for every
DEFINE_STATIC_CALL_RET0 for CONFIG_HAVE_STATIC_CALL=n, e.g. using typeof() to
get the prototype?

  Kernel panic - not syncing: CFI failure (target: __static_call_return0+0x0/0x8)
  CPU: 0 PID: 1625 Comm: batterystats-wo Tainted: G        W  OE     5.16.0-mainline #1$
  Hardware name: Raven EVT 1.1 (DT)$
  Call trace:$
   dump_backtrace+0xf0/0x130$
   show_stack+0x1c/0x2c$
   dump_stack_lvl+0x68/0x98$
   panic+0x168/0x420$
   __cfi_check_fail+0x58/0x5c$
   __cfi_slowpath_diag+0x150/0x1a4$
   perf_misc_flags+0x74/0xa4$
   perf_prepare_sample+0x50/0x44c$
   perf_event_output_forward+0x5c/0xcc$
   __perf_event_overflow+0xc8/0x188$
   perf_swevent_event+0x7c/0x10c$
   perf_tp_event+0x168/0x298$
   perf_trace_run_bpf_submit+0x8c/0xdc$
   perf_trace_sched_switch+0x180/0x1cc$
   __schedule+0x850/0x924$
   schedule+0x98/0xe0$
   binder_wait_for_work+0x158/0x368$
   binder_thread_read+0x278/0x243c$
   binder_ioctl_write_read+0x120/0x45c$
   binder_ioctl+0x1ac/0xc34$
   __arm64_sys_ioctl+0xa8/0x118$
   invoke_syscall+0x64/0x178$
   el0_svc_common+0x8c/0x100$
   do_el0_svc+0x28/0xa0$
   el0_svc+0x24/0x84$
   el0t_64_sync_handler+0x88/0xec$
   el0t_64_sync+0x1b4/0x1b8$

Re: [PATCH v4 09/17] perf/core: Use static_call to optimize perf_guest_info_callbacks

[Sami Tolvanen]

On Wed, Feb 2, 2022 at 10:43 AM Sean Christopherson <seanjc@google.com> wrote:
> > +DEFINE_STATIC_CALL_RET0(__perf_guest_state, *perf_guest_cbs->state);
> > +DEFINE_STATIC_CALL_RET0(__perf_guest_get_ip, *perf_guest_cbs->get_ip);
> > +DEFINE_STATIC_CALL_RET0(__perf_guest_handle_intel_pt_intr, *perf_guest_cbs->handle_intel_pt_intr);
>
> Using __static_call_return0() makes clang's CFI sad on arm64 due to the resulting
> function prototype mistmatch, which IIUC, is verified by clang's __cfi_check()
> for indirect calls, i.e. architectures without CONFIG_HAVE_STATIC_CALL.
>
> We could fudge around the issue by using stubs, massaging prototypes, etc..., but
> that means doing that for every arch-agnostic user of __static_call_return0().
>
> Any clever ideas?  Can we do something like generate a unique function for every
> DEFINE_STATIC_CALL_RET0 for CONFIG_HAVE_STATIC_CALL=n, e.g. using typeof() to
> get the prototype?

I'm not sure there's a clever fix for this. On architectures without
HAVE_STATIC_CALL, this is an indirect call to a function with a
mismatching type, which CFI is intended to catch.

The obvious way to solve the problem would be to use a stub function
with the correct type, which I agree, isn't going to scale. You can
alternatively check if .func points to __static_call_return0 and not
make the indirect call if it does. If neither of these options are
feasible, you can disable CFI checking in the functions that have
these static calls using the __nocfi attribute.

Kees, any thoughts?

Sami

Re: [PATCH v4 09/17] perf/core: Use static_call to optimize perf_guest_info_callbacks

[Peter Zijlstra]

On Fri, Feb 04, 2022 at 09:35:49AM -0800, Sami Tolvanen wrote:
> On Wed, Feb 2, 2022 at 10:43 AM Sean Christopherson <seanjc@google.com> wrote:
> > > +DEFINE_STATIC_CALL_RET0(__perf_guest_state, *perf_guest_cbs->state);
> > > +DEFINE_STATIC_CALL_RET0(__perf_guest_get_ip, *perf_guest_cbs->get_ip);
> > > +DEFINE_STATIC_CALL_RET0(__perf_guest_handle_intel_pt_intr, *perf_guest_cbs->handle_intel_pt_intr);
> >
> > Using __static_call_return0() makes clang's CFI sad on arm64 due to the resulting
> > function prototype mistmatch, which IIUC, is verified by clang's __cfi_check()
> > for indirect calls, i.e. architectures without CONFIG_HAVE_STATIC_CALL.
> >
> > We could fudge around the issue by using stubs, massaging prototypes, etc..., but
> > that means doing that for every arch-agnostic user of __static_call_return0().
> >
> > Any clever ideas?  Can we do something like generate a unique function for every
> > DEFINE_STATIC_CALL_RET0 for CONFIG_HAVE_STATIC_CALL=n, e.g. using typeof() to
> > get the prototype?
> 
> I'm not sure there's a clever fix for this. On architectures without
> HAVE_STATIC_CALL, this is an indirect call to a function with a
> mismatching type, which CFI is intended to catch.
> 
> The obvious way to solve the problem would be to use a stub function
> with the correct type, which I agree, isn't going to scale. You can
> alternatively check if .func points to __static_call_return0 and not
> make the indirect call if it does. If neither of these options are
> feasible, you can disable CFI checking in the functions that have
> these static calls using the __nocfi attribute.

There's also the tp_stub_func() thing that does basically the same
thing.

Re: [PATCH v4 09/17] perf/core: Use static_call to optimize perf_guest_info_callbacks

[Kees Cook]

On Fri, Feb 04, 2022 at 09:35:49AM -0800, Sami Tolvanen wrote:
> On Wed, Feb 2, 2022 at 10:43 AM Sean Christopherson <seanjc@google.com> wrote:
> > > +DEFINE_STATIC_CALL_RET0(__perf_guest_state, *perf_guest_cbs->state);
> > > +DEFINE_STATIC_CALL_RET0(__perf_guest_get_ip, *perf_guest_cbs->get_ip);
> > > +DEFINE_STATIC_CALL_RET0(__perf_guest_handle_intel_pt_intr, *perf_guest_cbs->handle_intel_pt_intr);
> >
> > Using __static_call_return0() makes clang's CFI sad on arm64 due to the resulting
> > function prototype mistmatch, which IIUC, is verified by clang's __cfi_check()
> > for indirect calls, i.e. architectures without CONFIG_HAVE_STATIC_CALL.
> >
> > We could fudge around the issue by using stubs, massaging prototypes, etc..., but
> > that means doing that for every arch-agnostic user of __static_call_return0().
> >
> > Any clever ideas?  Can we do something like generate a unique function for every
> > DEFINE_STATIC_CALL_RET0 for CONFIG_HAVE_STATIC_CALL=n, e.g. using typeof() to
> > get the prototype?
> 
> I'm not sure there's a clever fix for this. On architectures without
> HAVE_STATIC_CALL, this is an indirect call to a function with a
> mismatching type, which CFI is intended to catch.
> 
> The obvious way to solve the problem would be to use a stub function
> with the correct type, which I agree, isn't going to scale. You can
> alternatively check if .func points to __static_call_return0 and not
> make the indirect call if it does. If neither of these options are
> feasible, you can disable CFI checking in the functions that have
> these static calls using the __nocfi attribute.
> 
> Kees, any thoughts?

I'm digging through the macros to sort this out, but IIUC, an example of
the problem is:

perf_guest_cbs->handle_intel_pt_intr is:

	unsigned int (*handle_intel_pt_intr)(void);

The declaration for this starts with:

DECLARE_STATIC_CALL(__perf_guest_handle_intel_pt_intr, *perf_guest_cbs->handle_intel_pt_intr);

which produces:

extern struct static_call_key STATIC_CALL_KEY(__perf_guest_handle_intel_pt_intr);
extern typeof(*perf_guest_cbs->handle_intel_pt_intr) STATIC_CALL_TRAMP(__perf_guest_handle_intel_pt_intr);

and the last line becomes:

extern unsigned int (*__SCT____perf_guest_handle_intel_pt_intr)(void);

with !HAVE_STATIC_CALL, when perf_guest_handle_intel_pt_intr() does:

	return static_call(__perf_guest_handle_intel_pt_intr)();

it is resolving static_call() into:

	((typeof(STATIC_CALL_TRAMP(name))*)(STATIC_CALL_KEY(name).func))

so the caller is expecting "unsigned int (*)(void)" but the prototype
of __static_call_return0 is "long (*)(void)":

long __static_call_return0(void);

Could we simply declare a type-matched ret0 trampoline too?

#define STATIC_CALL_TRAMP_RET0_PREFIX	__SCT__ret0__
#define STATIC_CALL_TRAMP_RET0(name)	__PASTE(STATIC_CALL_TRAMP_RET0_PREFIX, name)

#define DEFINE_STATIC_CALL_RET0(name, _func)				\
	static typeof(_func) STATIC_CALL_TRAMP_RET0(name) { return 0; }	\
        __DEFINE_STATIC_CALL(name, _func, STATIC_CALL_TRAMP_RET0(name));

static_call_update(__perf_guest_handle_intel_pt_intr,
		   (void *)&STATIC_CALL_TRAMP_RET0(__perf_guest_handle_intel_pt_intr))

-- 
Kees Cook

Re: [PATCH v4 09/17] perf/core: Use static_call to optimize perf_guest_info_callbacks

[Peter Zijlstra]

On Sun, Feb 06, 2022 at 10:45:15AM -0800, Kees Cook wrote:

> I'm digging through the macros to sort this out, but IIUC, an example of
> the problem is:
> 

> so the caller is expecting "unsigned int (*)(void)" but the prototype
> of __static_call_return0 is "long (*)(void)":
> 
> long __static_call_return0(void);
> 
> Could we simply declare a type-matched ret0 trampoline too?

That'll work for this case, but the next case the function will have
arguments we'll need even more nonsense...

And as stated in that other email, there's tb_stub_func() having the
exact same problem as well.

The x86_64 CFI patches had a work-around for this, that could trivially
be lifted I suppose.

Re: [PATCH v4 09/17] perf/core: Use static_call to optimize perf_guest_info_callbacks

[Kees Cook]

On Sun, Feb 06, 2022 at 09:28:52PM +0100, Peter Zijlstra wrote:
> On Sun, Feb 06, 2022 at 10:45:15AM -0800, Kees Cook wrote:
> 
> > I'm digging through the macros to sort this out, but IIUC, an example of
> > the problem is:
> > 
> 
> > so the caller is expecting "unsigned int (*)(void)" but the prototype
> > of __static_call_return0 is "long (*)(void)":
> > 
> > long __static_call_return0(void);
> > 
> > Could we simply declare a type-matched ret0 trampoline too?
> 
> That'll work for this case, but the next case the function will have
> arguments we'll need even more nonsense...

Shouldn't the typeof() work there too, though? I.e. as long as the
return value can hold a "0", it'd work.

> And as stated in that other email, there's tb_stub_func() having the
> exact same problem as well.

Yeah, I'd need to go look at that again.

> The x86_64 CFI patches had a work-around for this, that could trivially
> be lifted I suppose.

Yeah, I think it'd be similar. I haven't had a chance to go look at that
again...

-- 
Kees Cook

Re: [PATCH v4 09/17] perf/core: Use static_call to optimize perf_guest_info_callbacks

[Will McVicker]

On Sun, Feb 6, 2022 at 6:56 PM Kees Cook <keescook@chromium.org> wrote:
>
> On Sun, Feb 06, 2022 at 09:28:52PM +0100, Peter Zijlstra wrote:
> > On Sun, Feb 06, 2022 at 10:45:15AM -0800, Kees Cook wrote:
> >
> > > I'm digging through the macros to sort this out, but IIUC, an example of
> > > the problem is:
> > >
> >
> > > so the caller is expecting "unsigned int (*)(void)" but the prototype
> > > of __static_call_return0 is "long (*)(void)":
> > >
> > > long __static_call_return0(void);
> > >
> > > Could we simply declare a type-matched ret0 trampoline too?
> >
> > That'll work for this case, but the next case the function will have
> > arguments we'll need even more nonsense...
>
> Shouldn't the typeof() work there too, though? I.e. as long as the
> return value can hold a "0", it'd work.
>
> > And as stated in that other email, there's tb_stub_func() having the
> > exact same problem as well.
>
> Yeah, I'd need to go look at that again.
>
> > The x86_64 CFI patches had a work-around for this, that could trivially
> > be lifted I suppose.
>
> Yeah, I think it'd be similar. I haven't had a chance to go look at that
> again...
>
> --
> Kees Cook


Hi All,

I noticed that this thread kind of died out. Does anyone have any
action items that need to be followed up to help resolve this issue?
The offending patch is breaking the ARM64 Android Common Kernels
(Pixel 6 in particular) and I imagine it might also have an impact on
other ARM64 platforms upstream that just haven't hit this perf_trace
case yet.

If anyone needs help verifying any fixes, I'm happy to test it out.

Thanks,
Will

Re: [PATCH v4 09/17] perf/core: Use static_call to optimize perf_guest_info_callbacks

[Sean Christopherson]

On Fri, Feb 18, 2022, Will McVicker wrote:
> On Sun, Feb 6, 2022 at 6:56 PM Kees Cook <keescook@chromium.org> wrote:
> >
> > On Sun, Feb 06, 2022 at 09:28:52PM +0100, Peter Zijlstra wrote:
> > > On Sun, Feb 06, 2022 at 10:45:15AM -0800, Kees Cook wrote:
> > >
> > > > I'm digging through the macros to sort this out, but IIUC, an example of
> > > > the problem is:
> > > >
> > >
> > > > so the caller is expecting "unsigned int (*)(void)" but the prototype
> > > > of __static_call_return0 is "long (*)(void)":
> > > >
> > > > long __static_call_return0(void);
> > > >
> > > > Could we simply declare a type-matched ret0 trampoline too?
> > >
> > > That'll work for this case, but the next case the function will have
> > > arguments we'll need even more nonsense...
> >
> > Shouldn't the typeof() work there too, though? I.e. as long as the
> > return value can hold a "0", it'd work.
> >
> > > And as stated in that other email, there's tb_stub_func() having the
> > > exact same problem as well.
> >
> > Yeah, I'd need to go look at that again.
> >
> > > The x86_64 CFI patches had a work-around for this, that could trivially
> > > be lifted I suppose.
> >
> > Yeah, I think it'd be similar. I haven't had a chance to go look at that
> > again...

Peter and/or Kees, can you provide a pointer to the patches that could potentially
be used as a basis for fixing ARM CFI?  Or even better, send a patch to actually
fix this?  :-)

[PATCH v4 10/17] KVM: x86: Drop current_vcpu for kvm_running_vcpu + kvm_arch_vcpu variable

[Sean Christopherson]

Use the generic kvm_running_vcpu plus a new 'handling_intr_from_guest'
variable in kvm_arch_vcpu instead of the semi-redundant current_vcpu.
kvm_before/after_interrupt() must be called while the vCPU is loaded,
(which protects against preemption), thus kvm_running_vcpu is guaranteed
to be non-NULL when handling_intr_from_guest is non-zero.

Switching to kvm_get_running_vcpu() will allows moving KVM's perf
callbacks to generic code, and the new flag will be used in a future
patch to more precisely identify the "NMI from guest" case.

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/include/asm/kvm_host.h |  3 +--
 arch/x86/kvm/pmu.c              |  2 +-
 arch/x86/kvm/x86.c              | 21 ++++++++++++---------
 arch/x86/kvm/x86.h              | 10 ++++++----
 4 files changed, 20 insertions(+), 16 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 112ffb355552..812c08e797fe 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -773,6 +773,7 @@ struct kvm_vcpu_arch {
 	unsigned nmi_pending; /* NMI queued after currently running handler */
 	bool nmi_injected;    /* Trying to inject an NMI this entry */
 	bool smi_pending;    /* SMI queued after currently running handler */
+	u8 handling_intr_from_guest;
 
 	struct kvm_mtrr mtrr_state;
 	u64 pat;
@@ -1893,8 +1894,6 @@ int kvm_skip_emulated_instruction(struct kvm_vcpu *vcpu);
 int kvm_complete_insn_gp(struct kvm_vcpu *vcpu, int err);
 void __kvm_request_immediate_exit(struct kvm_vcpu *vcpu);
 
-unsigned int kvm_guest_state(void);
-
 void __user *__x86_set_memory_region(struct kvm *kvm, int id, gpa_t gpa,
 				     u32 size);
 bool kvm_vcpu_is_reset_bsp(struct kvm_vcpu *vcpu);
diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index 5b68d4188de0..eef48258e50f 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -87,7 +87,7 @@ static void kvm_perf_overflow_intr(struct perf_event *perf_event,
 		 * woken up. So we should wake it, but this is impossible from
 		 * NMI context. Do it from irq work instead.
 		 */
-		if (!kvm_guest_state())
+		if (!kvm_handling_nmi_from_guest(pmc->vcpu))
 			irq_work_queue(&pmc_to_pmu(pmc)->irq_work);
 		else
 			kvm_make_request(KVM_REQ_PMI, pmc->vcpu);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ceb09d78277e..c8ef49385c99 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8410,15 +8410,17 @@ static void kvm_timer_init(void)
 			  kvmclock_cpu_online, kvmclock_cpu_down_prep);
 }
 
-DEFINE_PER_CPU(struct kvm_vcpu *, current_vcpu);
-EXPORT_PER_CPU_SYMBOL_GPL(current_vcpu);
+static inline bool kvm_pmi_in_guest(struct kvm_vcpu *vcpu)
+{
+	return vcpu && vcpu->arch.handling_intr_from_guest;
+}
 
-unsigned int kvm_guest_state(void)
+static unsigned int kvm_guest_state(void)
 {
-	struct kvm_vcpu *vcpu = __this_cpu_read(current_vcpu);
+	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
 	unsigned int state;
 
-	if (!vcpu)
+	if (!kvm_pmi_in_guest(vcpu))
 		return 0;
 
 	state = PERF_GUEST_ACTIVE;
@@ -8430,9 +8432,10 @@ unsigned int kvm_guest_state(void)
 
 static unsigned long kvm_guest_get_ip(void)
 {
-	struct kvm_vcpu *vcpu = __this_cpu_read(current_vcpu);
+	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
 
-	if (WARN_ON_ONCE(!vcpu))
+	/* Retrieving the IP must be guarded by a call to kvm_guest_state(). */
+	if (WARN_ON_ONCE(!kvm_pmi_in_guest(vcpu)))
 		return 0;
 
 	return kvm_rip_read(vcpu);
@@ -8440,10 +8443,10 @@ static unsigned long kvm_guest_get_ip(void)
 
 static unsigned int kvm_handle_intel_pt_intr(void)
 {
-	struct kvm_vcpu *vcpu = __this_cpu_read(current_vcpu);
+	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
 
 	/* '0' on failure so that the !PT case can use a RET0 static call. */
-	if (!vcpu)
+	if (!kvm_pmi_in_guest(vcpu))
 		return 0;
 
 	kvm_make_request(KVM_REQ_PMI, vcpu);
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index ea264c4502e4..d070043fd2e8 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -385,18 +385,20 @@ static inline bool kvm_cstate_in_guest(struct kvm *kvm)
 	return kvm->arch.cstate_in_guest;
 }
 
-DECLARE_PER_CPU(struct kvm_vcpu *, current_vcpu);
-
 static inline void kvm_before_interrupt(struct kvm_vcpu *vcpu)
 {
-	__this_cpu_write(current_vcpu, vcpu);
+	WRITE_ONCE(vcpu->arch.handling_intr_from_guest, 1);
 }
 
 static inline void kvm_after_interrupt(struct kvm_vcpu *vcpu)
 {
-	__this_cpu_write(current_vcpu, NULL);
+	WRITE_ONCE(vcpu->arch.handling_intr_from_guest, 0);
 }
 
+static inline bool kvm_handling_nmi_from_guest(struct kvm_vcpu *vcpu)
+{
+	return !!vcpu->arch.handling_intr_from_guest;
+}
 
 static inline bool kvm_pat_valid(u64 data)
 {
-- 
2.34.0.rc0.344.g81b53c2807-goog

[tip: perf/core] KVM: x86: Drop current_vcpu for kvm_running_vcpu + kvm_arch_vcpu variable

[tip-bot2 for Sean Christopherson]

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     73cd107b9685c5308e864061772e4a78a629e4a0
Gitweb:        https://git.kernel.org/tip/73cd107b9685c5308e864061772e4a78a629e4a0
Author:        Sean Christopherson <seanjc@google.com>
AuthorDate:    Thu, 11 Nov 2021 02:07:31 
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Wed, 17 Nov 2021 14:49:09 +01:00

KVM: x86: Drop current_vcpu for kvm_running_vcpu + kvm_arch_vcpu variable

Use the generic kvm_running_vcpu plus a new 'handling_intr_from_guest'
variable in kvm_arch_vcpu instead of the semi-redundant current_vcpu.
kvm_before/after_interrupt() must be called while the vCPU is loaded,
(which protects against preemption), thus kvm_running_vcpu is guaranteed
to be non-NULL when handling_intr_from_guest is non-zero.

Switching to kvm_get_running_vcpu() will allows moving KVM's perf
callbacks to generic code, and the new flag will be used in a future
patch to more precisely identify the "NMI from guest" case.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Link: https://lore.kernel.org/r/20211111020738.2512932-11-seanjc@google.com
---
 arch/x86/include/asm/kvm_host.h |  3 +--
 arch/x86/kvm/pmu.c              |  2 +-
 arch/x86/kvm/x86.c              | 21 ++++++++++++---------
 arch/x86/kvm/x86.h              | 10 ++++++----
 4 files changed, 20 insertions(+), 16 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index fa1b1a2..38f01b0 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -773,6 +773,7 @@ struct kvm_vcpu_arch {
 	unsigned nmi_pending; /* NMI queued after currently running handler */
 	bool nmi_injected;    /* Trying to inject an NMI this entry */
 	bool smi_pending;    /* SMI queued after currently running handler */
+	u8 handling_intr_from_guest;
 
 	struct kvm_mtrr mtrr_state;
 	u64 pat;
@@ -1895,8 +1896,6 @@ int kvm_skip_emulated_instruction(struct kvm_vcpu *vcpu);
 int kvm_complete_insn_gp(struct kvm_vcpu *vcpu, int err);
 void __kvm_request_immediate_exit(struct kvm_vcpu *vcpu);
 
-unsigned int kvm_guest_state(void);
-
 void __user *__x86_set_memory_region(struct kvm *kvm, int id, gpa_t gpa,
 				     u32 size);
 bool kvm_vcpu_is_reset_bsp(struct kvm_vcpu *vcpu);
diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index b2520b3..0c2133e 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -87,7 +87,7 @@ static void kvm_perf_overflow_intr(struct perf_event *perf_event,
 		 * woken up. So we should wake it, but this is impossible from
 		 * NMI context. Do it from irq work instead.
 		 */
-		if (!kvm_guest_state())
+		if (!kvm_handling_nmi_from_guest(pmc->vcpu))
 			irq_work_queue(&pmc_to_pmu(pmc)->irq_work);
 		else
 			kvm_make_request(KVM_REQ_PMI, pmc->vcpu);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 2011a1c..bb71e10 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8469,15 +8469,17 @@ static void kvm_timer_init(void)
 			  kvmclock_cpu_online, kvmclock_cpu_down_prep);
 }
 
-DEFINE_PER_CPU(struct kvm_vcpu *, current_vcpu);
-EXPORT_PER_CPU_SYMBOL_GPL(current_vcpu);
+static inline bool kvm_pmi_in_guest(struct kvm_vcpu *vcpu)
+{
+	return vcpu && vcpu->arch.handling_intr_from_guest;
+}
 
-unsigned int kvm_guest_state(void)
+static unsigned int kvm_guest_state(void)
 {
-	struct kvm_vcpu *vcpu = __this_cpu_read(current_vcpu);
+	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
 	unsigned int state;
 
-	if (!vcpu)
+	if (!kvm_pmi_in_guest(vcpu))
 		return 0;
 
 	state = PERF_GUEST_ACTIVE;
@@ -8489,9 +8491,10 @@ unsigned int kvm_guest_state(void)
 
 static unsigned long kvm_guest_get_ip(void)
 {
-	struct kvm_vcpu *vcpu = __this_cpu_read(current_vcpu);
+	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
 
-	if (WARN_ON_ONCE(!vcpu))
+	/* Retrieving the IP must be guarded by a call to kvm_guest_state(). */
+	if (WARN_ON_ONCE(!kvm_pmi_in_guest(vcpu)))
 		return 0;
 
 	return kvm_rip_read(vcpu);
@@ -8499,10 +8502,10 @@ static unsigned long kvm_guest_get_ip(void)
 
 static unsigned int kvm_handle_intel_pt_intr(void)
 {
-	struct kvm_vcpu *vcpu = __this_cpu_read(current_vcpu);
+	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
 
 	/* '0' on failure so that the !PT case can use a RET0 static call. */
-	if (!vcpu)
+	if (!kvm_pmi_in_guest(vcpu))
 		return 0;
 
 	kvm_make_request(KVM_REQ_PMI, vcpu);
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index ea264c4..d070043 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -385,18 +385,20 @@ static inline bool kvm_cstate_in_guest(struct kvm *kvm)
 	return kvm->arch.cstate_in_guest;
 }
 
-DECLARE_PER_CPU(struct kvm_vcpu *, current_vcpu);
-
 static inline void kvm_before_interrupt(struct kvm_vcpu *vcpu)
 {
-	__this_cpu_write(current_vcpu, vcpu);
+	WRITE_ONCE(vcpu->arch.handling_intr_from_guest, 1);
 }
 
 static inline void kvm_after_interrupt(struct kvm_vcpu *vcpu)
 {
-	__this_cpu_write(current_vcpu, NULL);
+	WRITE_ONCE(vcpu->arch.handling_intr_from_guest, 0);
 }
 
+static inline bool kvm_handling_nmi_from_guest(struct kvm_vcpu *vcpu)
+{
+	return !!vcpu->arch.handling_intr_from_guest;
+}
 
 static inline bool kvm_pat_valid(u64 data)
 {

[PATCH v4 11/17] KVM: x86: More precisely identify NMI from guest when handling PMI

[Sean Christopherson]

Differentiate between IRQ and NMI for KVM's PMC overflow callback, which
was originally invoked in response to an NMI that arrived while the guest
was running, but was inadvertantly changed to fire on IRQs as well when
support for perf without PMU/NMI was added to KVM.  In practice, this
should be a nop as the PMC overflow callback shouldn't be reached, but
it's a cheap and easy fix that also better documents the situation.

Note, this also doesn't completely prevent false positives if perf
somehow ends up calling into KVM, e.g. an NMI can arrive in host after
KVM sets its flag.

Fixes: dd60d217062f ("KVM: x86: Fix perf timer mode IP reporting")
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/svm/svm.c |  2 +-
 arch/x86/kvm/vmx/vmx.c |  4 +++-
 arch/x86/kvm/x86.c     |  2 +-
 arch/x86/kvm/x86.h     | 13 ++++++++++---
 4 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index b36ca4e476c2..df6a3e0bdcde 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -3936,7 +3936,7 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu)
 	}
 
 	if (unlikely(svm->vmcb->control.exit_code == SVM_EXIT_NMI))
-		kvm_before_interrupt(vcpu);
+		kvm_before_interrupt(vcpu, KVM_HANDLING_NMI);
 
 	kvm_load_host_xsave_state(vcpu);
 	stgi();
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 0927d07b2efb..36098eb9a7f9 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6371,7 +6371,9 @@ void vmx_do_interrupt_nmi_irqoff(unsigned long entry);
 static void handle_interrupt_nmi_irqoff(struct kvm_vcpu *vcpu,
 					unsigned long entry)
 {
-	kvm_before_interrupt(vcpu);
+	bool is_nmi = entry == (unsigned long)asm_exc_nmi_noist;
+
+	kvm_before_interrupt(vcpu, is_nmi ? KVM_HANDLING_NMI : KVM_HANDLING_IRQ);
 	vmx_do_interrupt_nmi_irqoff(entry);
 	kvm_after_interrupt(vcpu);
 }
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c8ef49385c99..e9e1a4bb1d00 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9837,7 +9837,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
 	 * interrupts on processors that implement an interrupt shadow, the
 	 * stat.exits increment will do nicely.
 	 */
-	kvm_before_interrupt(vcpu);
+	kvm_before_interrupt(vcpu, KVM_HANDLING_IRQ);
 	local_irq_enable();
 	++vcpu->stat.exits;
 	local_irq_disable();
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index d070043fd2e8..f8d2c58feadc 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -385,9 +385,16 @@ static inline bool kvm_cstate_in_guest(struct kvm *kvm)
 	return kvm->arch.cstate_in_guest;
 }
 
-static inline void kvm_before_interrupt(struct kvm_vcpu *vcpu)
+enum kvm_intr_type {
+	/* Values are arbitrary, but must be non-zero. */
+	KVM_HANDLING_IRQ = 1,
+	KVM_HANDLING_NMI,
+};
+
+static inline void kvm_before_interrupt(struct kvm_vcpu *vcpu,
+					enum kvm_intr_type intr)
 {
-	WRITE_ONCE(vcpu->arch.handling_intr_from_guest, 1);
+	WRITE_ONCE(vcpu->arch.handling_intr_from_guest, (u8)intr);
 }
 
 static inline void kvm_after_interrupt(struct kvm_vcpu *vcpu)
@@ -397,7 +404,7 @@ static inline void kvm_after_interrupt(struct kvm_vcpu *vcpu)
 
 static inline bool kvm_handling_nmi_from_guest(struct kvm_vcpu *vcpu)
 {
-	return !!vcpu->arch.handling_intr_from_guest;
+	return vcpu->arch.handling_intr_from_guest == KVM_HANDLING_NMI;
 }
 
 static inline bool kvm_pat_valid(u64 data)
-- 
2.34.0.rc0.344.g81b53c2807-goog

[tip: perf/core] KVM: x86: More precisely identify NMI from guest when handling PMI

[tip-bot2 for Sean Christopherson]

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     db215756ae5970aec8ad50257d2eb1678b552b91
Gitweb:        https://git.kernel.org/tip/db215756ae5970aec8ad50257d2eb1678b552b91
Author:        Sean Christopherson <seanjc@google.com>
AuthorDate:    Thu, 11 Nov 2021 02:07:32 
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Wed, 17 Nov 2021 14:49:09 +01:00

KVM: x86: More precisely identify NMI from guest when handling PMI

Differentiate between IRQ and NMI for KVM's PMC overflow callback, which
was originally invoked in response to an NMI that arrived while the guest
was running, but was inadvertantly changed to fire on IRQs as well when
support for perf without PMU/NMI was added to KVM.  In practice, this
should be a nop as the PMC overflow callback shouldn't be reached, but
it's a cheap and easy fix that also better documents the situation.

Note, this also doesn't completely prevent false positives if perf
somehow ends up calling into KVM, e.g. an NMI can arrive in host after
KVM sets its flag.

Fixes: dd60d217062f ("KVM: x86: Fix perf timer mode IP reporting")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Link: https://lore.kernel.org/r/20211111020738.2512932-12-seanjc@google.com
---
 arch/x86/kvm/svm/svm.c |  2 +-
 arch/x86/kvm/vmx/vmx.c |  4 +++-
 arch/x86/kvm/x86.c     |  2 +-
 arch/x86/kvm/x86.h     | 13 ++++++++++---
 4 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 5630c24..b2f0c6c 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -3931,7 +3931,7 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu)
 	}
 
 	if (unlikely(svm->vmcb->control.exit_code == SVM_EXIT_NMI))
-		kvm_before_interrupt(vcpu);
+		kvm_before_interrupt(vcpu, KVM_HANDLING_NMI);
 
 	kvm_load_host_xsave_state(vcpu);
 	stgi();
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 7d90c8d..a0c2497 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6317,7 +6317,9 @@ void vmx_do_interrupt_nmi_irqoff(unsigned long entry);
 static void handle_interrupt_nmi_irqoff(struct kvm_vcpu *vcpu,
 					unsigned long entry)
 {
-	kvm_before_interrupt(vcpu);
+	bool is_nmi = entry == (unsigned long)asm_exc_nmi_noist;
+
+	kvm_before_interrupt(vcpu, is_nmi ? KVM_HANDLING_NMI : KVM_HANDLING_IRQ);
 	vmx_do_interrupt_nmi_irqoff(entry);
 	kvm_after_interrupt(vcpu);
 }
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index bb71e10..ab032ef 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9896,7 +9896,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
 	 * interrupts on processors that implement an interrupt shadow, the
 	 * stat.exits increment will do nicely.
 	 */
-	kvm_before_interrupt(vcpu);
+	kvm_before_interrupt(vcpu, KVM_HANDLING_IRQ);
 	local_irq_enable();
 	++vcpu->stat.exits;
 	local_irq_disable();
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index d070043..f8d2c58 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -385,9 +385,16 @@ static inline bool kvm_cstate_in_guest(struct kvm *kvm)
 	return kvm->arch.cstate_in_guest;
 }
 
-static inline void kvm_before_interrupt(struct kvm_vcpu *vcpu)
+enum kvm_intr_type {
+	/* Values are arbitrary, but must be non-zero. */
+	KVM_HANDLING_IRQ = 1,
+	KVM_HANDLING_NMI,
+};
+
+static inline void kvm_before_interrupt(struct kvm_vcpu *vcpu,
+					enum kvm_intr_type intr)
 {
-	WRITE_ONCE(vcpu->arch.handling_intr_from_guest, 1);
+	WRITE_ONCE(vcpu->arch.handling_intr_from_guest, (u8)intr);
 }
 
 static inline void kvm_after_interrupt(struct kvm_vcpu *vcpu)
@@ -397,7 +404,7 @@ static inline void kvm_after_interrupt(struct kvm_vcpu *vcpu)
 
 static inline bool kvm_handling_nmi_from_guest(struct kvm_vcpu *vcpu)
 {
-	return !!vcpu->arch.handling_intr_from_guest;
+	return vcpu->arch.handling_intr_from_guest == KVM_HANDLING_NMI;
 }
 
 static inline bool kvm_pat_valid(u64 data)

[PATCH v4 12/17] KVM: Move x86's perf guest info callbacks to generic KVM

[Sean Christopherson]

Move x86's perf guest callbacks into common KVM, as they are semantically
identical to arm64's callbacks (the only other such KVM callbacks).
arm64 will convert to the common versions in a future patch.

Implement the necessary arm64 arch hooks now to avoid having to provide
stubs or a temporary #define (from x86) to avoid arm64 compilation errors
when CONFIG_GUEST_PERF_EVENTS=y.

Acked-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/arm64/include/asm/kvm_host.h | 10 ++++++
 arch/arm64/kvm/arm.c              |  5 +++
 arch/x86/include/asm/kvm_host.h   |  3 ++
 arch/x86/kvm/x86.c                | 53 +++++++------------------------
 include/linux/kvm_host.h          | 10 ++++++
 virt/kvm/kvm_main.c               | 44 +++++++++++++++++++++++++
 6 files changed, 83 insertions(+), 42 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 5a76d9a76fd9..72e2afe6e8e3 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -678,6 +678,16 @@ int io_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa);
 void kvm_perf_init(void);
 void kvm_perf_teardown(void);
 
+/*
+ * Returns true if a Performance Monitoring Interrupt (PMI), a.k.a. perf event,
+ * arrived in guest context.  For arm64, any event that arrives while a vCPU is
+ * loaded is considered to be "in guest".
+ */
+static inline bool kvm_arch_pmi_in_guest(struct kvm_vcpu *vcpu)
+{
+	return IS_ENABLED(CONFIG_GUEST_PERF_EVENTS) && !!vcpu;
+}
+
 long kvm_hypercall_pv_features(struct kvm_vcpu *vcpu);
 gpa_t kvm_init_stolen_time(struct kvm_vcpu *vcpu);
 void kvm_update_stolen_time(struct kvm_vcpu *vcpu);
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index f5490afe1ebf..93c952375f3b 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -496,6 +496,11 @@ bool kvm_arch_vcpu_in_kernel(struct kvm_vcpu *vcpu)
 	return vcpu_mode_priv(vcpu);
 }
 
+unsigned long kvm_arch_vcpu_get_ip(struct kvm_vcpu *vcpu)
+{
+	return *vcpu_pc(vcpu);
+}
+
 /* Just ensure a guest exit from a particular CPU */
 static void exit_vm_noop(void *info)
 {
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 812c08e797fe..ec16f645cb8c 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1565,6 +1565,9 @@ static inline int kvm_arch_flush_remote_tlb(struct kvm *kvm)
 		return -ENOTSUPP;
 }
 
+#define kvm_arch_pmi_in_guest(vcpu) \
+	((vcpu) && (vcpu)->arch.handling_intr_from_guest)
+
 int kvm_mmu_module_init(void);
 void kvm_mmu_module_exit(void);
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index e9e1a4bb1d00..bafd2e78ad04 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8410,43 +8410,12 @@ static void kvm_timer_init(void)
 			  kvmclock_cpu_online, kvmclock_cpu_down_prep);
 }
 
-static inline bool kvm_pmi_in_guest(struct kvm_vcpu *vcpu)
-{
-	return vcpu && vcpu->arch.handling_intr_from_guest;
-}
-
-static unsigned int kvm_guest_state(void)
-{
-	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
-	unsigned int state;
-
-	if (!kvm_pmi_in_guest(vcpu))
-		return 0;
-
-	state = PERF_GUEST_ACTIVE;
-	if (static_call(kvm_x86_get_cpl)(vcpu))
-		state |= PERF_GUEST_USER;
-
-	return state;
-}
-
-static unsigned long kvm_guest_get_ip(void)
-{
-	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
-
-	/* Retrieving the IP must be guarded by a call to kvm_guest_state(). */
-	if (WARN_ON_ONCE(!kvm_pmi_in_guest(vcpu)))
-		return 0;
-
-	return kvm_rip_read(vcpu);
-}
-
 static unsigned int kvm_handle_intel_pt_intr(void)
 {
 	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
 
 	/* '0' on failure so that the !PT case can use a RET0 static call. */
-	if (!kvm_pmi_in_guest(vcpu))
+	if (!kvm_arch_pmi_in_guest(vcpu))
 		return 0;
 
 	kvm_make_request(KVM_REQ_PMI, vcpu);
@@ -8455,12 +8424,6 @@ static unsigned int kvm_handle_intel_pt_intr(void)
 	return 1;
 }
 
-static struct perf_guest_info_callbacks kvm_guest_cbs = {
-	.state			= kvm_guest_state,
-	.get_ip			= kvm_guest_get_ip,
-	.handle_intel_pt_intr	= NULL,
-};
-
 #ifdef CONFIG_X86_64
 static void pvclock_gtod_update_fn(struct work_struct *work)
 {
@@ -11153,9 +11116,11 @@ int kvm_arch_hardware_setup(void *opaque)
 	memcpy(&kvm_x86_ops, ops->runtime_ops, sizeof(kvm_x86_ops));
 	kvm_ops_static_call_update();
 
+	/* Temporary ugliness. */
 	if (ops->intel_pt_intr_in_guest && ops->intel_pt_intr_in_guest())
-		kvm_guest_cbs.handle_intel_pt_intr = kvm_handle_intel_pt_intr;
-	perf_register_guest_info_callbacks(&kvm_guest_cbs);
+		kvm_register_perf_callbacks(kvm_handle_intel_pt_intr);
+	else
+		kvm_register_perf_callbacks(NULL);
 
 	if (!kvm_cpu_cap_has(X86_FEATURE_XSAVES))
 		supported_xss = 0;
@@ -11184,8 +11149,7 @@ int kvm_arch_hardware_setup(void *opaque)
 
 void kvm_arch_hardware_unsetup(void)
 {
-	perf_unregister_guest_info_callbacks(&kvm_guest_cbs);
-	kvm_guest_cbs.handle_intel_pt_intr = NULL;
+	kvm_unregister_perf_callbacks();
 
 	static_call(kvm_x86_hardware_unsetup)();
 }
@@ -11776,6 +11740,11 @@ bool kvm_arch_vcpu_in_kernel(struct kvm_vcpu *vcpu)
 	return vcpu->arch.preempted_in_kernel;
 }
 
+unsigned long kvm_arch_vcpu_get_ip(struct kvm_vcpu *vcpu)
+{
+	return kvm_rip_read(vcpu);
+}
+
 int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu)
 {
 	return kvm_vcpu_exiting_guest_mode(vcpu) == IN_GUEST_MODE;
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 60a35d9fe259..da843044e0c1 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1162,6 +1162,16 @@ static inline bool kvm_arch_intc_initialized(struct kvm *kvm)
 }
 #endif
 
+#ifdef CONFIG_GUEST_PERF_EVENTS
+unsigned long kvm_arch_vcpu_get_ip(struct kvm_vcpu *vcpu);
+
+void kvm_register_perf_callbacks(unsigned int (*pt_intr_handler)(void));
+void kvm_unregister_perf_callbacks(void);
+#else
+static inline void kvm_register_perf_callbacks(void *ign) {}
+static inline void kvm_unregister_perf_callbacks(void) {}
+#endif /* CONFIG_GUEST_PERF_EVENTS */
+
 int kvm_arch_init_vm(struct kvm *kvm, unsigned long type);
 void kvm_arch_destroy_vm(struct kvm *kvm);
 void kvm_arch_sync_events(struct kvm *kvm);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 3f6d450355f0..75d32fc031b5 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -5479,6 +5479,50 @@ struct kvm_vcpu * __percpu *kvm_get_running_vcpus(void)
         return &kvm_running_vcpu;
 }
 
+#ifdef CONFIG_GUEST_PERF_EVENTS
+static unsigned int kvm_guest_state(void)
+{
+	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
+	unsigned int state;
+
+	if (!kvm_arch_pmi_in_guest(vcpu))
+		return 0;
+
+	state = PERF_GUEST_ACTIVE;
+	if (!kvm_arch_vcpu_in_kernel(vcpu))
+		state |= PERF_GUEST_USER;
+
+	return state;
+}
+
+static unsigned long kvm_guest_get_ip(void)
+{
+	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
+
+	/* Retrieving the IP must be guarded by a call to kvm_guest_state(). */
+	if (WARN_ON_ONCE(!kvm_arch_pmi_in_guest(vcpu)))
+		return 0;
+
+	return kvm_arch_vcpu_get_ip(vcpu);
+}
+
+static struct perf_guest_info_callbacks kvm_guest_cbs = {
+	.state			= kvm_guest_state,
+	.get_ip			= kvm_guest_get_ip,
+	.handle_intel_pt_intr	= NULL,
+};
+
+void kvm_register_perf_callbacks(unsigned int (*pt_intr_handler)(void))
+{
+	kvm_guest_cbs.handle_intel_pt_intr = pt_intr_handler;
+	perf_register_guest_info_callbacks(&kvm_guest_cbs);
+}
+void kvm_unregister_perf_callbacks(void)
+{
+	perf_unregister_guest_info_callbacks(&kvm_guest_cbs);
+}
+#endif
+
 struct kvm_cpu_compat_check {
 	void *opaque;
 	int *ret;
-- 
2.34.0.rc0.344.g81b53c2807-goog

[tip: perf/core] KVM: Move x86's perf guest info callbacks to generic KVM

[tip-bot2 for Sean Christopherson]

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     e1bfc24577cc65c95dc519d7621a9c985b97e567
Gitweb:        https://git.kernel.org/tip/e1bfc24577cc65c95dc519d7621a9c985b97e567
Author:        Sean Christopherson <seanjc@google.com>
AuthorDate:    Thu, 11 Nov 2021 02:07:33 
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Wed, 17 Nov 2021 14:49:10 +01:00

KVM: Move x86's perf guest info callbacks to generic KVM

Move x86's perf guest callbacks into common KVM, as they are semantically
identical to arm64's callbacks (the only other such KVM callbacks).
arm64 will convert to the common versions in a future patch.

Implement the necessary arm64 arch hooks now to avoid having to provide
stubs or a temporary #define (from x86) to avoid arm64 compilation errors
when CONFIG_GUEST_PERF_EVENTS=y.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211111020738.2512932-13-seanjc@google.com
---
 arch/arm64/include/asm/kvm_host.h | 10 ++++++-
 arch/arm64/kvm/arm.c              |  5 +++-
 arch/x86/include/asm/kvm_host.h   |  3 ++-
 arch/x86/kvm/x86.c                | 53 ++++++------------------------
 include/linux/kvm_host.h          | 10 ++++++-
 virt/kvm/kvm_main.c               | 44 +++++++++++++++++++++++++-
 6 files changed, 83 insertions(+), 42 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index f680f30..aa28b8e 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -678,6 +678,16 @@ int io_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa);
 void kvm_perf_init(void);
 void kvm_perf_teardown(void);
 
+/*
+ * Returns true if a Performance Monitoring Interrupt (PMI), a.k.a. perf event,
+ * arrived in guest context.  For arm64, any event that arrives while a vCPU is
+ * loaded is considered to be "in guest".
+ */
+static inline bool kvm_arch_pmi_in_guest(struct kvm_vcpu *vcpu)
+{
+	return IS_ENABLED(CONFIG_GUEST_PERF_EVENTS) && !!vcpu;
+}
+
 long kvm_hypercall_pv_features(struct kvm_vcpu *vcpu);
 gpa_t kvm_init_stolen_time(struct kvm_vcpu *vcpu);
 void kvm_update_stolen_time(struct kvm_vcpu *vcpu);
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 2f03cbf..b400be9 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -496,6 +496,11 @@ bool kvm_arch_vcpu_in_kernel(struct kvm_vcpu *vcpu)
 	return vcpu_mode_priv(vcpu);
 }
 
+unsigned long kvm_arch_vcpu_get_ip(struct kvm_vcpu *vcpu)
+{
+	return *vcpu_pc(vcpu);
+}
+
 /* Just ensure a guest exit from a particular CPU */
 static void exit_vm_noop(void *info)
 {
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 38f01b0..8957654 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1567,6 +1567,9 @@ static inline int kvm_arch_flush_remote_tlb(struct kvm *kvm)
 		return -ENOTSUPP;
 }
 
+#define kvm_arch_pmi_in_guest(vcpu) \
+	((vcpu) && (vcpu)->arch.handling_intr_from_guest)
+
 int kvm_mmu_module_init(void);
 void kvm_mmu_module_exit(void);
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ab032ef..32cb6f9 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8469,43 +8469,12 @@ static void kvm_timer_init(void)
 			  kvmclock_cpu_online, kvmclock_cpu_down_prep);
 }
 
-static inline bool kvm_pmi_in_guest(struct kvm_vcpu *vcpu)
-{
-	return vcpu && vcpu->arch.handling_intr_from_guest;
-}
-
-static unsigned int kvm_guest_state(void)
-{
-	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
-	unsigned int state;
-
-	if (!kvm_pmi_in_guest(vcpu))
-		return 0;
-
-	state = PERF_GUEST_ACTIVE;
-	if (static_call(kvm_x86_get_cpl)(vcpu))
-		state |= PERF_GUEST_USER;
-
-	return state;
-}
-
-static unsigned long kvm_guest_get_ip(void)
-{
-	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
-
-	/* Retrieving the IP must be guarded by a call to kvm_guest_state(). */
-	if (WARN_ON_ONCE(!kvm_pmi_in_guest(vcpu)))
-		return 0;
-
-	return kvm_rip_read(vcpu);
-}
-
 static unsigned int kvm_handle_intel_pt_intr(void)
 {
 	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
 
 	/* '0' on failure so that the !PT case can use a RET0 static call. */
-	if (!kvm_pmi_in_guest(vcpu))
+	if (!kvm_arch_pmi_in_guest(vcpu))
 		return 0;
 
 	kvm_make_request(KVM_REQ_PMI, vcpu);
@@ -8514,12 +8483,6 @@ static unsigned int kvm_handle_intel_pt_intr(void)
 	return 1;
 }
 
-static struct perf_guest_info_callbacks kvm_guest_cbs = {
-	.state			= kvm_guest_state,
-	.get_ip			= kvm_guest_get_ip,
-	.handle_intel_pt_intr	= NULL,
-};
-
 #ifdef CONFIG_X86_64
 static void pvclock_gtod_update_fn(struct work_struct *work)
 {
@@ -11229,9 +11192,11 @@ int kvm_arch_hardware_setup(void *opaque)
 	memcpy(&kvm_x86_ops, ops->runtime_ops, sizeof(kvm_x86_ops));
 	kvm_ops_static_call_update();
 
+	/* Temporary ugliness. */
 	if (ops->intel_pt_intr_in_guest && ops->intel_pt_intr_in_guest())
-		kvm_guest_cbs.handle_intel_pt_intr = kvm_handle_intel_pt_intr;
-	perf_register_guest_info_callbacks(&kvm_guest_cbs);
+		kvm_register_perf_callbacks(kvm_handle_intel_pt_intr);
+	else
+		kvm_register_perf_callbacks(NULL);
 
 	if (!kvm_cpu_cap_has(X86_FEATURE_XSAVES))
 		supported_xss = 0;
@@ -11260,8 +11225,7 @@ int kvm_arch_hardware_setup(void *opaque)
 
 void kvm_arch_hardware_unsetup(void)
 {
-	perf_unregister_guest_info_callbacks(&kvm_guest_cbs);
-	kvm_guest_cbs.handle_intel_pt_intr = NULL;
+	kvm_unregister_perf_callbacks();
 
 	static_call(kvm_x86_hardware_unsetup)();
 }
@@ -11852,6 +11816,11 @@ bool kvm_arch_vcpu_in_kernel(struct kvm_vcpu *vcpu)
 	return vcpu->arch.preempted_in_kernel;
 }
 
+unsigned long kvm_arch_vcpu_get_ip(struct kvm_vcpu *vcpu)
+{
+	return kvm_rip_read(vcpu);
+}
+
 int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu)
 {
 	return kvm_vcpu_exiting_guest_mode(vcpu) == IN_GUEST_MODE;
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 9e0667e..9df7ab2 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1170,6 +1170,16 @@ static inline bool kvm_arch_intc_initialized(struct kvm *kvm)
 }
 #endif
 
+#ifdef CONFIG_GUEST_PERF_EVENTS
+unsigned long kvm_arch_vcpu_get_ip(struct kvm_vcpu *vcpu);
+
+void kvm_register_perf_callbacks(unsigned int (*pt_intr_handler)(void));
+void kvm_unregister_perf_callbacks(void);
+#else
+static inline void kvm_register_perf_callbacks(void *ign) {}
+static inline void kvm_unregister_perf_callbacks(void) {}
+#endif /* CONFIG_GUEST_PERF_EVENTS */
+
 int kvm_arch_init_vm(struct kvm *kvm, unsigned long type);
 void kvm_arch_destroy_vm(struct kvm *kvm);
 void kvm_arch_sync_events(struct kvm *kvm);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index d317245..76778dd 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -5479,6 +5479,50 @@ struct kvm_vcpu * __percpu *kvm_get_running_vcpus(void)
         return &kvm_running_vcpu;
 }
 
+#ifdef CONFIG_GUEST_PERF_EVENTS
+static unsigned int kvm_guest_state(void)
+{
+	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
+	unsigned int state;
+
+	if (!kvm_arch_pmi_in_guest(vcpu))
+		return 0;
+
+	state = PERF_GUEST_ACTIVE;
+	if (!kvm_arch_vcpu_in_kernel(vcpu))
+		state |= PERF_GUEST_USER;
+
+	return state;
+}
+
+static unsigned long kvm_guest_get_ip(void)
+{
+	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
+
+	/* Retrieving the IP must be guarded by a call to kvm_guest_state(). */
+	if (WARN_ON_ONCE(!kvm_arch_pmi_in_guest(vcpu)))
+		return 0;
+
+	return kvm_arch_vcpu_get_ip(vcpu);
+}
+
+static struct perf_guest_info_callbacks kvm_guest_cbs = {
+	.state			= kvm_guest_state,
+	.get_ip			= kvm_guest_get_ip,
+	.handle_intel_pt_intr	= NULL,
+};
+
+void kvm_register_perf_callbacks(unsigned int (*pt_intr_handler)(void))
+{
+	kvm_guest_cbs.handle_intel_pt_intr = pt_intr_handler;
+	perf_register_guest_info_callbacks(&kvm_guest_cbs);
+}
+void kvm_unregister_perf_callbacks(void)
+{
+	perf_unregister_guest_info_callbacks(&kvm_guest_cbs);
+}
+#endif
+
 struct kvm_cpu_compat_check {
 	void *opaque;
 	int *ret;

[PATCH v4 13/17] KVM: x86: Move Intel Processor Trace interrupt handler to vmx.c

[Sean Christopherson]

Now that all state needed for VMX's PT interrupt handler is exposed to
vmx.c (specifically the currently running vCPU), move the handler into
vmx.c where it belongs.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/include/asm/kvm_host.h |  2 +-
 arch/x86/kvm/vmx/vmx.c          | 22 +++++++++++++++++++++-
 arch/x86/kvm/x86.c              | 20 +-------------------
 3 files changed, 23 insertions(+), 21 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index ec16f645cb8c..621bedff0aa5 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1515,7 +1515,7 @@ struct kvm_x86_init_ops {
 	int (*disabled_by_bios)(void);
 	int (*check_processor_compatibility)(void);
 	int (*hardware_setup)(void);
-	bool (*intel_pt_intr_in_guest)(void);
+	unsigned int (*handle_intel_pt_intr)(void);
 
 	struct kvm_x86_ops *runtime_ops;
 };
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 36098eb9a7f9..7cb7f261f7dc 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7708,6 +7708,20 @@ static struct kvm_x86_ops vmx_x86_ops __initdata = {
 	.vcpu_deliver_sipi_vector = kvm_vcpu_deliver_sipi_vector,
 };
 
+static unsigned int vmx_handle_intel_pt_intr(void)
+{
+	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
+
+	/* '0' on failure so that the !PT case can use a RET0 static call. */
+	if (!kvm_arch_pmi_in_guest(vcpu))
+		return 0;
+
+	kvm_make_request(KVM_REQ_PMI, vcpu);
+	__set_bit(MSR_CORE_PERF_GLOBAL_OVF_CTRL_TRACE_TOPA_PMI_BIT,
+		  (unsigned long *)&vcpu->arch.pmu.global_status);
+	return 1;
+}
+
 static __init void vmx_setup_user_return_msrs(void)
 {
 
@@ -7734,6 +7748,8 @@ static __init void vmx_setup_user_return_msrs(void)
 		kvm_add_user_return_msr(vmx_uret_msrs_list[i]);
 }
 
+static struct kvm_x86_init_ops vmx_init_ops __initdata;
+
 static __init int hardware_setup(void)
 {
 	unsigned long host_bndcfgs;
@@ -7892,6 +7908,10 @@ static __init int hardware_setup(void)
 		return -EINVAL;
 	if (!enable_ept || !cpu_has_vmx_intel_pt())
 		pt_mode = PT_MODE_SYSTEM;
+	if (pt_mode == PT_MODE_HOST_GUEST)
+		vmx_init_ops.handle_intel_pt_intr = vmx_handle_intel_pt_intr;
+	else
+		vmx_init_ops.handle_intel_pt_intr = NULL;
 
 	setup_default_sgx_lepubkeyhash();
 
@@ -7920,7 +7940,7 @@ static struct kvm_x86_init_ops vmx_init_ops __initdata = {
 	.disabled_by_bios = vmx_disabled_by_bios,
 	.check_processor_compatibility = vmx_check_processor_compat,
 	.hardware_setup = hardware_setup,
-	.intel_pt_intr_in_guest = vmx_pt_mode_is_host_guest,
+	.handle_intel_pt_intr = NULL,
 
 	.runtime_ops = &vmx_x86_ops,
 };
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index bafd2e78ad04..a4d25d0587e6 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8410,20 +8410,6 @@ static void kvm_timer_init(void)
 			  kvmclock_cpu_online, kvmclock_cpu_down_prep);
 }
 
-static unsigned int kvm_handle_intel_pt_intr(void)
-{
-	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
-
-	/* '0' on failure so that the !PT case can use a RET0 static call. */
-	if (!kvm_arch_pmi_in_guest(vcpu))
-		return 0;
-
-	kvm_make_request(KVM_REQ_PMI, vcpu);
-	__set_bit(MSR_CORE_PERF_GLOBAL_OVF_CTRL_TRACE_TOPA_PMI_BIT,
-			(unsigned long *)&vcpu->arch.pmu.global_status);
-	return 1;
-}
-
 #ifdef CONFIG_X86_64
 static void pvclock_gtod_update_fn(struct work_struct *work)
 {
@@ -11116,11 +11102,7 @@ int kvm_arch_hardware_setup(void *opaque)
 	memcpy(&kvm_x86_ops, ops->runtime_ops, sizeof(kvm_x86_ops));
 	kvm_ops_static_call_update();
 
-	/* Temporary ugliness. */
-	if (ops->intel_pt_intr_in_guest && ops->intel_pt_intr_in_guest())
-		kvm_register_perf_callbacks(kvm_handle_intel_pt_intr);
-	else
-		kvm_register_perf_callbacks(NULL);
+	kvm_register_perf_callbacks(ops->handle_intel_pt_intr);
 
 	if (!kvm_cpu_cap_has(X86_FEATURE_XSAVES))
 		supported_xss = 0;
-- 
2.34.0.rc0.344.g81b53c2807-goog

[tip: perf/core] KVM: x86: Move Intel Processor Trace interrupt handler to vmx.c

[tip-bot2 for Sean Christopherson]

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     33271a9e2b52e07e278a67c900d2d2afb5c55bd5
Gitweb:        https://git.kernel.org/tip/33271a9e2b52e07e278a67c900d2d2afb5c55bd5
Author:        Sean Christopherson <seanjc@google.com>
AuthorDate:    Thu, 11 Nov 2021 02:07:34 
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Wed, 17 Nov 2021 14:49:10 +01:00

KVM: x86: Move Intel Processor Trace interrupt handler to vmx.c

Now that all state needed for VMX's PT interrupt handler is exposed to
vmx.c (specifically the currently running vCPU), move the handler into
vmx.c where it belongs.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211111020738.2512932-14-seanjc@google.com
---
 arch/x86/include/asm/kvm_host.h |  2 +-
 arch/x86/kvm/vmx/vmx.c          | 22 +++++++++++++++++++++-
 arch/x86/kvm/x86.c              | 20 +-------------------
 3 files changed, 23 insertions(+), 21 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 8957654..298224f 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1517,7 +1517,7 @@ struct kvm_x86_init_ops {
 	int (*disabled_by_bios)(void);
 	int (*check_processor_compatibility)(void);
 	int (*hardware_setup)(void);
-	bool (*intel_pt_intr_in_guest)(void);
+	unsigned int (*handle_intel_pt_intr)(void);
 
 	struct kvm_x86_ops *runtime_ops;
 };
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index a0c2497..b258f90 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7655,6 +7655,20 @@ static struct kvm_x86_ops vmx_x86_ops __initdata = {
 	.vcpu_deliver_sipi_vector = kvm_vcpu_deliver_sipi_vector,
 };
 
+static unsigned int vmx_handle_intel_pt_intr(void)
+{
+	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
+
+	/* '0' on failure so that the !PT case can use a RET0 static call. */
+	if (!kvm_arch_pmi_in_guest(vcpu))
+		return 0;
+
+	kvm_make_request(KVM_REQ_PMI, vcpu);
+	__set_bit(MSR_CORE_PERF_GLOBAL_OVF_CTRL_TRACE_TOPA_PMI_BIT,
+		  (unsigned long *)&vcpu->arch.pmu.global_status);
+	return 1;
+}
+
 static __init void vmx_setup_user_return_msrs(void)
 {
 
@@ -7681,6 +7695,8 @@ static __init void vmx_setup_user_return_msrs(void)
 		kvm_add_user_return_msr(vmx_uret_msrs_list[i]);
 }
 
+static struct kvm_x86_init_ops vmx_init_ops __initdata;
+
 static __init int hardware_setup(void)
 {
 	unsigned long host_bndcfgs;
@@ -7839,6 +7855,10 @@ static __init int hardware_setup(void)
 		return -EINVAL;
 	if (!enable_ept || !cpu_has_vmx_intel_pt())
 		pt_mode = PT_MODE_SYSTEM;
+	if (pt_mode == PT_MODE_HOST_GUEST)
+		vmx_init_ops.handle_intel_pt_intr = vmx_handle_intel_pt_intr;
+	else
+		vmx_init_ops.handle_intel_pt_intr = NULL;
 
 	setup_default_sgx_lepubkeyhash();
 
@@ -7867,7 +7887,7 @@ static struct kvm_x86_init_ops vmx_init_ops __initdata = {
 	.disabled_by_bios = vmx_disabled_by_bios,
 	.check_processor_compatibility = vmx_check_processor_compat,
 	.hardware_setup = hardware_setup,
-	.intel_pt_intr_in_guest = vmx_pt_mode_is_host_guest,
+	.handle_intel_pt_intr = NULL,
 
 	.runtime_ops = &vmx_x86_ops,
 };
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 32cb6f9..4e0ed2f 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8469,20 +8469,6 @@ static void kvm_timer_init(void)
 			  kvmclock_cpu_online, kvmclock_cpu_down_prep);
 }
 
-static unsigned int kvm_handle_intel_pt_intr(void)
-{
-	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
-
-	/* '0' on failure so that the !PT case can use a RET0 static call. */
-	if (!kvm_arch_pmi_in_guest(vcpu))
-		return 0;
-
-	kvm_make_request(KVM_REQ_PMI, vcpu);
-	__set_bit(MSR_CORE_PERF_GLOBAL_OVF_CTRL_TRACE_TOPA_PMI_BIT,
-			(unsigned long *)&vcpu->arch.pmu.global_status);
-	return 1;
-}
-
 #ifdef CONFIG_X86_64
 static void pvclock_gtod_update_fn(struct work_struct *work)
 {
@@ -11192,11 +11178,7 @@ int kvm_arch_hardware_setup(void *opaque)
 	memcpy(&kvm_x86_ops, ops->runtime_ops, sizeof(kvm_x86_ops));
 	kvm_ops_static_call_update();
 
-	/* Temporary ugliness. */
-	if (ops->intel_pt_intr_in_guest && ops->intel_pt_intr_in_guest())
-		kvm_register_perf_callbacks(kvm_handle_intel_pt_intr);
-	else
-		kvm_register_perf_callbacks(NULL);
+	kvm_register_perf_callbacks(ops->handle_intel_pt_intr);
 
 	if (!kvm_cpu_cap_has(X86_FEATURE_XSAVES))
 		supported_xss = 0;

[PATCH v4 14/17] KVM: arm64: Convert to the generic perf callbacks

[Sean Christopherson]

Drop arm64's version of the callbacks in favor of the callbacks provided
by generic KVM, which are semantically identical.

Reviewed-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/arm64/kvm/perf.c | 34 ++--------------------------------
 1 file changed, 2 insertions(+), 32 deletions(-)

diff --git a/arch/arm64/kvm/perf.c b/arch/arm64/kvm/perf.c
index dfa9bce8559e..374c496a3f1d 100644
--- a/arch/arm64/kvm/perf.c
+++ b/arch/arm64/kvm/perf.c
@@ -13,42 +13,12 @@
 
 DEFINE_STATIC_KEY_FALSE(kvm_arm_pmu_available);
 
-static unsigned int kvm_guest_state(void)
-{
-	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
-	unsigned int state;
-
-	if (!vcpu)
-		return 0;
-
-	state = PERF_GUEST_ACTIVE;
-	if (!vcpu_mode_priv(vcpu))
-		state |= PERF_GUEST_USER;
-
-	return state;
-}
-
-static unsigned long kvm_get_guest_ip(void)
-{
-	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
-
-	if (WARN_ON_ONCE(!vcpu))
-		return 0;
-
-	return *vcpu_pc(vcpu);
-}
-
-static struct perf_guest_info_callbacks kvm_guest_cbs = {
-	.state		= kvm_guest_state,
-	.get_ip		= kvm_get_guest_ip,
-};
-
 void kvm_perf_init(void)
 {
-	perf_register_guest_info_callbacks(&kvm_guest_cbs);
+	kvm_register_perf_callbacks(NULL);
 }
 
 void kvm_perf_teardown(void)
 {
-	perf_unregister_guest_info_callbacks(&kvm_guest_cbs);
+	kvm_unregister_perf_callbacks();
 }
-- 
2.34.0.rc0.344.g81b53c2807-goog

[tip: perf/core] KVM: arm64: Convert to the generic perf callbacks

[tip-bot2 for Sean Christopherson]

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     7b517831a1c6aceb0821860edb9c7bc7d4f803a2
Gitweb:        https://git.kernel.org/tip/7b517831a1c6aceb0821860edb9c7bc7d4f803a2
Author:        Sean Christopherson <seanjc@google.com>
AuthorDate:    Thu, 11 Nov 2021 02:07:35 
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Wed, 17 Nov 2021 14:49:11 +01:00

KVM: arm64: Convert to the generic perf callbacks

Drop arm64's version of the callbacks in favor of the callbacks provided
by generic KVM, which are semantically identical.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211111020738.2512932-15-seanjc@google.com
---
 arch/arm64/kvm/perf.c | 34 ++--------------------------------
 1 file changed, 2 insertions(+), 32 deletions(-)

diff --git a/arch/arm64/kvm/perf.c b/arch/arm64/kvm/perf.c
index dfa9bce..374c496 100644
--- a/arch/arm64/kvm/perf.c
+++ b/arch/arm64/kvm/perf.c
@@ -13,42 +13,12 @@
 
 DEFINE_STATIC_KEY_FALSE(kvm_arm_pmu_available);
 
-static unsigned int kvm_guest_state(void)
-{
-	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
-	unsigned int state;
-
-	if (!vcpu)
-		return 0;
-
-	state = PERF_GUEST_ACTIVE;
-	if (!vcpu_mode_priv(vcpu))
-		state |= PERF_GUEST_USER;
-
-	return state;
-}
-
-static unsigned long kvm_get_guest_ip(void)
-{
-	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
-
-	if (WARN_ON_ONCE(!vcpu))
-		return 0;
-
-	return *vcpu_pc(vcpu);
-}
-
-static struct perf_guest_info_callbacks kvm_guest_cbs = {
-	.state		= kvm_guest_state,
-	.get_ip		= kvm_get_guest_ip,
-};
-
 void kvm_perf_init(void)
 {
-	perf_register_guest_info_callbacks(&kvm_guest_cbs);
+	kvm_register_perf_callbacks(NULL);
 }
 
 void kvm_perf_teardown(void)
 {
-	perf_unregister_guest_info_callbacks(&kvm_guest_cbs);
+	kvm_unregister_perf_callbacks();
 }

[PATCH v4 15/17] KVM: arm64: Hide kvm_arm_pmu_available behind CONFIG_HW_PERF_EVENTS=y

[Sean Christopherson]

Move the definition of kvm_arm_pmu_available to pmu-emul.c and, out of
"necessity", hide it behind CONFIG_HW_PERF_EVENTS.  Provide a stub for
the key's wrapper, kvm_arm_support_pmu_v3().  Moving the key's definition
out of perf.c will allow a future commit to delete perf.c entirely.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/arm64/kernel/image-vars.h |  2 ++
 arch/arm64/kvm/perf.c          |  2 --
 arch/arm64/kvm/pmu-emul.c      |  2 ++
 include/kvm/arm_pmu.h          | 19 ++++++++++++-------
 4 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/arch/arm64/kernel/image-vars.h b/arch/arm64/kernel/image-vars.h
index c96a9a0043bf..7eaf1f7c4168 100644
--- a/arch/arm64/kernel/image-vars.h
+++ b/arch/arm64/kernel/image-vars.h
@@ -102,7 +102,9 @@ KVM_NVHE_ALIAS(__stop___kvm_ex_table);
 KVM_NVHE_ALIAS(kvm_arm_hyp_percpu_base);
 
 /* PMU available static key */
+#ifdef CONFIG_HW_PERF_EVENTS
 KVM_NVHE_ALIAS(kvm_arm_pmu_available);
+#endif
 
 /* Position-independent library routines */
 KVM_NVHE_ALIAS_HYP(clear_page, __pi_clear_page);
diff --git a/arch/arm64/kvm/perf.c b/arch/arm64/kvm/perf.c
index 374c496a3f1d..52cfab253c65 100644
--- a/arch/arm64/kvm/perf.c
+++ b/arch/arm64/kvm/perf.c
@@ -11,8 +11,6 @@
 
 #include <asm/kvm_emulate.h>
 
-DEFINE_STATIC_KEY_FALSE(kvm_arm_pmu_available);
-
 void kvm_perf_init(void)
 {
 	kvm_register_perf_callbacks(NULL);
diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index a5e4bbf5e68f..3308ceefa129 100644
--- a/arch/arm64/kvm/pmu-emul.c
+++ b/arch/arm64/kvm/pmu-emul.c
@@ -14,6 +14,8 @@
 #include <kvm/arm_pmu.h>
 #include <kvm/arm_vgic.h>
 
+DEFINE_STATIC_KEY_FALSE(kvm_arm_pmu_available);
+
 static void kvm_pmu_create_perf_event(struct kvm_vcpu *vcpu, u64 select_idx);
 static void kvm_pmu_update_pmc_chained(struct kvm_vcpu *vcpu, u64 select_idx);
 static void kvm_pmu_stop_counter(struct kvm_vcpu *vcpu, struct kvm_pmc *pmc);
diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
index 90f21898aad8..f9ed4c171d7b 100644
--- a/include/kvm/arm_pmu.h
+++ b/include/kvm/arm_pmu.h
@@ -13,13 +13,6 @@
 #define ARMV8_PMU_CYCLE_IDX		(ARMV8_PMU_MAX_COUNTERS - 1)
 #define ARMV8_PMU_MAX_COUNTER_PAIRS	((ARMV8_PMU_MAX_COUNTERS + 1) >> 1)
 
-DECLARE_STATIC_KEY_FALSE(kvm_arm_pmu_available);
-
-static __always_inline bool kvm_arm_support_pmu_v3(void)
-{
-	return static_branch_likely(&kvm_arm_pmu_available);
-}
-
 #ifdef CONFIG_HW_PERF_EVENTS
 
 struct kvm_pmc {
@@ -36,6 +29,13 @@ struct kvm_pmu {
 	struct irq_work overflow_work;
 };
 
+DECLARE_STATIC_KEY_FALSE(kvm_arm_pmu_available);
+
+static __always_inline bool kvm_arm_support_pmu_v3(void)
+{
+	return static_branch_likely(&kvm_arm_pmu_available);
+}
+
 #define kvm_arm_pmu_irq_initialized(v)	((v)->arch.pmu.irq_num >= VGIC_NR_SGIS)
 u64 kvm_pmu_get_counter_value(struct kvm_vcpu *vcpu, u64 select_idx);
 void kvm_pmu_set_counter_value(struct kvm_vcpu *vcpu, u64 select_idx, u64 val);
@@ -65,6 +65,11 @@ int kvm_arm_pmu_v3_enable(struct kvm_vcpu *vcpu);
 struct kvm_pmu {
 };
 
+static inline bool kvm_arm_support_pmu_v3(void)
+{
+	return false;
+}
+
 #define kvm_arm_pmu_irq_initialized(v)	(false)
 static inline u64 kvm_pmu_get_counter_value(struct kvm_vcpu *vcpu,
 					    u64 select_idx)
-- 
2.34.0.rc0.344.g81b53c2807-goog

Re: [PATCH v4 15/17] KVM: arm64: Hide kvm_arm_pmu_available behind CONFIG_HW_PERF_EVENTS=y

[Marc Zyngier]

On Thu, 11 Nov 2021 02:07:36 +0000,
Sean Christopherson <seanjc@google.com> wrote:
> 
> Move the definition of kvm_arm_pmu_available to pmu-emul.c and, out of
> "necessity", hide it behind CONFIG_HW_PERF_EVENTS.  Provide a stub for
> the key's wrapper, kvm_arm_support_pmu_v3().  Moving the key's definition
> out of perf.c will allow a future commit to delete perf.c entirely.
> 
> Signed-off-by: Sean Christopherson <seanjc@google.com>

Reviewed-by: Marc Zyngier <maz@kernel.org>

	M.

-- 
Without deviation from the norm, progress is not possible.

[tip: perf/core] KVM: arm64: Hide kvm_arm_pmu_available behind CONFIG_HW_PERF_EVENTS=y

[tip-bot2 for Sean Christopherson]

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     be399d824b432a85f8df86b566d2e5994fdf58b0
Gitweb:        https://git.kernel.org/tip/be399d824b432a85f8df86b566d2e5994fdf58b0
Author:        Sean Christopherson <seanjc@google.com>
AuthorDate:    Thu, 11 Nov 2021 02:07:36 
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Wed, 17 Nov 2021 14:49:11 +01:00

KVM: arm64: Hide kvm_arm_pmu_available behind CONFIG_HW_PERF_EVENTS=y

Move the definition of kvm_arm_pmu_available to pmu-emul.c and, out of
"necessity", hide it behind CONFIG_HW_PERF_EVENTS.  Provide a stub for
the key's wrapper, kvm_arm_support_pmu_v3().  Moving the key's definition
out of perf.c will allow a future commit to delete perf.c entirely.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211111020738.2512932-16-seanjc@google.com
---
 arch/arm64/kernel/image-vars.h |  2 ++
 arch/arm64/kvm/perf.c          |  2 --
 arch/arm64/kvm/pmu-emul.c      |  2 ++
 include/kvm/arm_pmu.h          | 19 ++++++++++++-------
 4 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/arch/arm64/kernel/image-vars.h b/arch/arm64/kernel/image-vars.h
index c96a9a0..7eaf1f7 100644
--- a/arch/arm64/kernel/image-vars.h
+++ b/arch/arm64/kernel/image-vars.h
@@ -102,7 +102,9 @@ KVM_NVHE_ALIAS(__stop___kvm_ex_table);
 KVM_NVHE_ALIAS(kvm_arm_hyp_percpu_base);
 
 /* PMU available static key */
+#ifdef CONFIG_HW_PERF_EVENTS
 KVM_NVHE_ALIAS(kvm_arm_pmu_available);
+#endif
 
 /* Position-independent library routines */
 KVM_NVHE_ALIAS_HYP(clear_page, __pi_clear_page);
diff --git a/arch/arm64/kvm/perf.c b/arch/arm64/kvm/perf.c
index 374c496..52cfab2 100644
--- a/arch/arm64/kvm/perf.c
+++ b/arch/arm64/kvm/perf.c
@@ -11,8 +11,6 @@
 
 #include <asm/kvm_emulate.h>
 
-DEFINE_STATIC_KEY_FALSE(kvm_arm_pmu_available);
-
 void kvm_perf_init(void)
 {
 	kvm_register_perf_callbacks(NULL);
diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index a5e4bbf..3308cee 100644
--- a/arch/arm64/kvm/pmu-emul.c
+++ b/arch/arm64/kvm/pmu-emul.c
@@ -14,6 +14,8 @@
 #include <kvm/arm_pmu.h>
 #include <kvm/arm_vgic.h>
 
+DEFINE_STATIC_KEY_FALSE(kvm_arm_pmu_available);
+
 static void kvm_pmu_create_perf_event(struct kvm_vcpu *vcpu, u64 select_idx);
 static void kvm_pmu_update_pmc_chained(struct kvm_vcpu *vcpu, u64 select_idx);
 static void kvm_pmu_stop_counter(struct kvm_vcpu *vcpu, struct kvm_pmc *pmc);
diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
index 90f2189..f9ed4c1 100644
--- a/include/kvm/arm_pmu.h
+++ b/include/kvm/arm_pmu.h
@@ -13,13 +13,6 @@
 #define ARMV8_PMU_CYCLE_IDX		(ARMV8_PMU_MAX_COUNTERS - 1)
 #define ARMV8_PMU_MAX_COUNTER_PAIRS	((ARMV8_PMU_MAX_COUNTERS + 1) >> 1)
 
-DECLARE_STATIC_KEY_FALSE(kvm_arm_pmu_available);
-
-static __always_inline bool kvm_arm_support_pmu_v3(void)
-{
-	return static_branch_likely(&kvm_arm_pmu_available);
-}
-
 #ifdef CONFIG_HW_PERF_EVENTS
 
 struct kvm_pmc {
@@ -36,6 +29,13 @@ struct kvm_pmu {
 	struct irq_work overflow_work;
 };
 
+DECLARE_STATIC_KEY_FALSE(kvm_arm_pmu_available);
+
+static __always_inline bool kvm_arm_support_pmu_v3(void)
+{
+	return static_branch_likely(&kvm_arm_pmu_available);
+}
+
 #define kvm_arm_pmu_irq_initialized(v)	((v)->arch.pmu.irq_num >= VGIC_NR_SGIS)
 u64 kvm_pmu_get_counter_value(struct kvm_vcpu *vcpu, u64 select_idx);
 void kvm_pmu_set_counter_value(struct kvm_vcpu *vcpu, u64 select_idx, u64 val);
@@ -65,6 +65,11 @@ int kvm_arm_pmu_v3_enable(struct kvm_vcpu *vcpu);
 struct kvm_pmu {
 };
 
+static inline bool kvm_arm_support_pmu_v3(void)
+{
+	return false;
+}
+
 #define kvm_arm_pmu_irq_initialized(v)	(false)
 static inline u64 kvm_pmu_get_counter_value(struct kvm_vcpu *vcpu,
 					    u64 select_idx)

[PATCH v4 16/17] KVM: arm64: Drop perf.c and fold its tiny bits of code into arm.c

[Sean Christopherson]

Call KVM's (un)register perf callbacks helpers directly from arm.c and
delete perf.c

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/arm64/include/asm/kvm_host.h |  3 ---
 arch/arm64/kvm/Makefile           |  2 +-
 arch/arm64/kvm/arm.c              |  5 +++--
 arch/arm64/kvm/perf.c             | 22 ----------------------
 4 files changed, 4 insertions(+), 28 deletions(-)
 delete mode 100644 arch/arm64/kvm/perf.c

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 72e2afe6e8e3..824040b174ab 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -675,9 +675,6 @@ unsigned long kvm_mmio_read_buf(const void *buf, unsigned int len);
 int kvm_handle_mmio_return(struct kvm_vcpu *vcpu);
 int io_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa);
 
-void kvm_perf_init(void);
-void kvm_perf_teardown(void);
-
 /*
  * Returns true if a Performance Monitoring Interrupt (PMI), a.k.a. perf event,
  * arrived in guest context.  For arm64, any event that arrives while a vCPU is
diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile
index 989bb5dad2c8..0bcc378b7961 100644
--- a/arch/arm64/kvm/Makefile
+++ b/arch/arm64/kvm/Makefile
@@ -12,7 +12,7 @@ obj-$(CONFIG_KVM) += hyp/
 
 kvm-y := $(KVM)/kvm_main.o $(KVM)/coalesced_mmio.o $(KVM)/eventfd.o \
 	 $(KVM)/vfio.o $(KVM)/irqchip.o $(KVM)/binary_stats.o \
-	 arm.o mmu.o mmio.o psci.o perf.o hypercalls.o pvtime.o \
+	 arm.o mmu.o mmio.o psci.o hypercalls.o pvtime.o \
 	 inject_fault.o va_layout.o handle_exit.o \
 	 guest.o debug.o reset.o sys_regs.o \
 	 vgic-sys-reg-v3.o fpsimd.o pmu.o \
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 93c952375f3b..8d18a64a72f1 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1776,7 +1776,8 @@ static int init_subsystems(void)
 	if (err)
 		goto out;
 
-	kvm_perf_init();
+	kvm_register_perf_callbacks(NULL);
+
 	kvm_sys_reg_table_init();
 
 out:
@@ -2164,7 +2165,7 @@ int kvm_arch_init(void *opaque)
 /* NOP: Compiling as a module not supported */
 void kvm_arch_exit(void)
 {
-	kvm_perf_teardown();
+	kvm_unregister_perf_callbacks();
 }
 
 static int __init early_kvm_mode_cfg(char *arg)
diff --git a/arch/arm64/kvm/perf.c b/arch/arm64/kvm/perf.c
deleted file mode 100644
index 52cfab253c65..000000000000
--- a/arch/arm64/kvm/perf.c
+++ /dev/null
@@ -1,22 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-only
-/*
- * Based on the x86 implementation.
- *
- * Copyright (C) 2012 ARM Ltd.
- * Author: Marc Zyngier <marc.zyngier@arm.com>
- */
-
-#include <linux/perf_event.h>
-#include <linux/kvm_host.h>
-
-#include <asm/kvm_emulate.h>
-
-void kvm_perf_init(void)
-{
-	kvm_register_perf_callbacks(NULL);
-}
-
-void kvm_perf_teardown(void)
-{
-	kvm_unregister_perf_callbacks();
-}
-- 
2.34.0.rc0.344.g81b53c2807-goog

Re: [PATCH v4 16/17] KVM: arm64: Drop perf.c and fold its tiny bits of code into arm.c

[Marc Zyngier]

On Thu, 11 Nov 2021 02:07:37 +0000,
Sean Christopherson <seanjc@google.com> wrote:
> 
> Call KVM's (un)register perf callbacks helpers directly from arm.c and
> delete perf.c
> 
> No functional change intended.
> 
> Signed-off-by: Sean Christopherson <seanjc@google.com>

Reviewed-by: Marc Zyngier <maz@kernel.org>

	M.

-- 
Without deviation from the norm, progress is not possible.

[tip: perf/core] KVM: arm64: Drop perf.c and fold its tiny bits of code into arm.c

[tip-bot2 for Sean Christopherson]

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     17ed14eba22b3a86e82fb6df28af00fb4cadfd77
Gitweb:        https://git.kernel.org/tip/17ed14eba22b3a86e82fb6df28af00fb4cadfd77
Author:        Sean Christopherson <seanjc@google.com>
AuthorDate:    Thu, 11 Nov 2021 02:07:37 
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Wed, 17 Nov 2021 14:49:11 +01:00

KVM: arm64: Drop perf.c and fold its tiny bits of code into arm.c

Call KVM's (un)register perf callbacks helpers directly from arm.c and
delete perf.c

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211111020738.2512932-17-seanjc@google.com
---
 arch/arm64/include/asm/kvm_host.h |  3 ---
 arch/arm64/kvm/Makefile           |  2 +-
 arch/arm64/kvm/arm.c              |  5 +++--
 arch/arm64/kvm/perf.c             | 22 ----------------------
 4 files changed, 4 insertions(+), 28 deletions(-)
 delete mode 100644 arch/arm64/kvm/perf.c

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index aa28b8e..541e7a8 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -675,9 +675,6 @@ unsigned long kvm_mmio_read_buf(const void *buf, unsigned int len);
 int kvm_handle_mmio_return(struct kvm_vcpu *vcpu);
 int io_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa);
 
-void kvm_perf_init(void);
-void kvm_perf_teardown(void);
-
 /*
  * Returns true if a Performance Monitoring Interrupt (PMI), a.k.a. perf event,
  * arrived in guest context.  For arm64, any event that arrives while a vCPU is
diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile
index 989bb5d..0bcc378 100644
--- a/arch/arm64/kvm/Makefile
+++ b/arch/arm64/kvm/Makefile
@@ -12,7 +12,7 @@ obj-$(CONFIG_KVM) += hyp/
 
 kvm-y := $(KVM)/kvm_main.o $(KVM)/coalesced_mmio.o $(KVM)/eventfd.o \
 	 $(KVM)/vfio.o $(KVM)/irqchip.o $(KVM)/binary_stats.o \
-	 arm.o mmu.o mmio.o psci.o perf.o hypercalls.o pvtime.o \
+	 arm.o mmu.o mmio.o psci.o hypercalls.o pvtime.o \
 	 inject_fault.o va_layout.o handle_exit.o \
 	 guest.o debug.o reset.o sys_regs.o \
 	 vgic-sys-reg-v3.o fpsimd.o pmu.o \
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index b400be9..8129ee1 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1773,7 +1773,8 @@ static int init_subsystems(void)
 	if (err)
 		goto out;
 
-	kvm_perf_init();
+	kvm_register_perf_callbacks(NULL);
+
 	kvm_sys_reg_table_init();
 
 out:
@@ -2161,7 +2162,7 @@ out_err:
 /* NOP: Compiling as a module not supported */
 void kvm_arch_exit(void)
 {
-	kvm_perf_teardown();
+	kvm_unregister_perf_callbacks();
 }
 
 static int __init early_kvm_mode_cfg(char *arg)
diff --git a/arch/arm64/kvm/perf.c b/arch/arm64/kvm/perf.c
deleted file mode 100644
index 52cfab2..0000000
--- a/arch/arm64/kvm/perf.c
+++ /dev/null
@@ -1,22 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-only
-/*
- * Based on the x86 implementation.
- *
- * Copyright (C) 2012 ARM Ltd.
- * Author: Marc Zyngier <marc.zyngier@arm.com>
- */
-
-#include <linux/perf_event.h>
-#include <linux/kvm_host.h>
-
-#include <asm/kvm_emulate.h>
-
-void kvm_perf_init(void)
-{
-	kvm_register_perf_callbacks(NULL);
-}
-
-void kvm_perf_teardown(void)
-{
-	kvm_unregister_perf_callbacks();
-}

[PATCH v4 17/17] perf: Drop guest callback (un)register stubs

[Sean Christopherson]

Drop perf's stubs for (un)registering guest callbacks now that KVM
registration of callbacks is hidden behind GUEST_PERF_EVENTS=y.  The only
other user is x86 XEN_PV, and x86 unconditionally selects PERF_EVENTS.

No functional change intended.

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 include/linux/perf_event.h | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 0ac7d867ca0c..7b7525e9155f 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1511,11 +1511,6 @@ perf_sw_event(u32 event_id, u64 nr, struct pt_regs *regs, u64 addr)	{ }
 static inline void
 perf_bp_event(struct perf_event *event, void *data)			{ }
 
-static inline void perf_register_guest_info_callbacks
-(struct perf_guest_info_callbacks *cbs)					{ }
-static inline void perf_unregister_guest_info_callbacks
-(struct perf_guest_info_callbacks *cbs)					{ }
-
 static inline void perf_event_mmap(struct vm_area_struct *vma)		{ }
 
 typedef int (perf_ksymbol_get_name_f)(char *name, int name_len, void *data);
-- 
2.34.0.rc0.344.g81b53c2807-goog

[tip: perf/core] perf: Drop guest callback (un)register stubs

[tip-bot2 for Sean Christopherson]

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     a9f4a6e92b3b319296fb078da2615f618f6cd80c
Gitweb:        https://git.kernel.org/tip/a9f4a6e92b3b319296fb078da2615f618f6cd80c
Author:        Sean Christopherson <seanjc@google.com>
AuthorDate:    Thu, 11 Nov 2021 02:07:38 
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Wed, 17 Nov 2021 14:49:12 +01:00

perf: Drop guest callback (un)register stubs

Drop perf's stubs for (un)registering guest callbacks now that KVM
registration of callbacks is hidden behind GUEST_PERF_EVENTS=y.  The only
other user is x86 XEN_PV, and x86 unconditionally selects PERF_EVENTS.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Link: https://lore.kernel.org/r/20211111020738.2512932-18-seanjc@google.com
---
 include/linux/perf_event.h | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 0ac7d86..7b7525e 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1511,11 +1511,6 @@ perf_sw_event(u32 event_id, u64 nr, struct pt_regs *regs, u64 addr)	{ }
 static inline void
 perf_bp_event(struct perf_event *event, void *data)			{ }
 
-static inline void perf_register_guest_info_callbacks
-(struct perf_guest_info_callbacks *cbs)					{ }
-static inline void perf_unregister_guest_info_callbacks
-(struct perf_guest_info_callbacks *cbs)					{ }
-
 static inline void perf_event_mmap(struct vm_area_struct *vma)		{ }
 
 typedef int (perf_ksymbol_get_name_f)(char *name, int name_len, void *data);

Re: [PATCH v4 00/17] perf: KVM: Fix, optimize, and clean up callbacks

[Peter Zijlstra]

On Thu, Nov 11, 2021 at 02:07:21AM +0000, Sean Christopherson wrote:

> Like Xu (1):
>   perf/core: Rework guest callbacks to prepare for static_call support
> 
> Sean Christopherson (16):
>   perf: Protect perf_guest_cbs with RCU
>   KVM: x86: Register perf callbacks after calling vendor's
>     hardware_setup()
>   KVM: x86: Register Processor Trace interrupt hook iff PT enabled in
>     guest
>   perf: Stop pretending that perf can handle multiple guest callbacks
>   perf: Drop dead and useless guest "support" from arm, csky, nds32 and
>     riscv
>   perf: Add wrappers for invoking guest callbacks
>   perf: Force architectures to opt-in to guest callbacks
>   perf/core: Use static_call to optimize perf_guest_info_callbacks
>   KVM: x86: Drop current_vcpu for kvm_running_vcpu + kvm_arch_vcpu
>     variable
>   KVM: x86: More precisely identify NMI from guest when handling PMI
>   KVM: Move x86's perf guest info callbacks to generic KVM
>   KVM: x86: Move Intel Processor Trace interrupt handler to vmx.c
>   KVM: arm64: Convert to the generic perf callbacks
>   KVM: arm64: Hide kvm_arm_pmu_available behind CONFIG_HW_PERF_EVENTS=y
>   KVM: arm64: Drop perf.c and fold its tiny bits of code into arm.c
>   perf: Drop guest callback (un)register stubs

Thanks!, I'll queue them up and push them into tip/perf/core once -rc1
happens.