[PATCH v4 0/4] KVM: arm64: Do not communicate host pmu event changes by accessing hyp data

[PATCH v4 0/4] KVM: arm64: Do not communicate host pmu event changes by accessing hyp data

[Fuad Tabba]

Hi,

This series changes the way KVM communicates host pmu event changes to the
hypervisor in nvhe and protected mode. Instead of accessing hyp data directly
from the host, the data is passed to hyp via the loaded vcpu. This provides
more isolation between the host and the hypervisor, and allows us to use pmu in
protected mode.

This series is based on kvmarm/next (8c22fd2d4cfa).

Changes since V3 [1]:
- Fix/clarify commit messages (Oliver)
- Reduce scope of kvm_pmu_events (Oliver/Marc)

Changes since V2 [2]:
- Update the guest view of the pmu events after interrupts have been disabled
  (Marc)

Changes since V1 [3]:
- Repack struct kvm_pmu to remove all (two) holes (Marc)
- Updating the guest's view of the pmu events before every vcpu run rather than
  vcpu load to avoid missing updates (Marc)

Thanks,
/fuad

[1] https://lore.kernel.org/all/20220509120330.3043773-1-tabba@google.com/
[2] https://lore.kernel.org/all/20220509095500.2408785-1-tabba@google.com/
[3] https://lore.kernel.org/linux-arm-kernel/20220408084052.3310931-1-tabba@google.com/

Fuad Tabba (4):
  KVM: arm64: Wrapper for getting pmu_events
  KVM: arm64: Repack struct kvm_pmu to reduce size
  KVM: arm64: Pass pmu events to hyp via vcpu
  KVM: arm64: Reenable pmu in Protected Mode

 arch/arm64/include/asm/kvm_host.h |  7 +-----
 arch/arm64/kvm/arm.c              | 15 ++++++++++++
 arch/arm64/kvm/hyp/nvhe/switch.c  | 20 +++++-----------
 arch/arm64/kvm/pmu-emul.c         |  3 +--
 arch/arm64/kvm/pmu.c              | 40 ++++++++++++++++++-------------
 include/kvm/arm_pmu.h             | 10 ++++++--
 6 files changed, 54 insertions(+), 41 deletions(-)


base-commit: 8c22fd2d4cfaab2ae3c5859496c894df58ab014b
-- 
2.36.0.512.ge40c2bad7a-goog

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kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm

[PATCH v4 0/4] KVM: arm64: Do not communicate host pmu event changes by accessing hyp data

[Fuad Tabba]

Hi,

This series changes the way KVM communicates host pmu event changes to the
hypervisor in nvhe and protected mode. Instead of accessing hyp data directly
from the host, the data is passed to hyp via the loaded vcpu. This provides
more isolation between the host and the hypervisor, and allows us to use pmu in
protected mode.

This series is based on kvmarm/next (8c22fd2d4cfa).

Changes since V3 [1]:
- Fix/clarify commit messages (Oliver)
- Reduce scope of kvm_pmu_events (Oliver/Marc)

Changes since V2 [2]:
- Update the guest view of the pmu events after interrupts have been disabled
  (Marc)

Changes since V1 [3]:
- Repack struct kvm_pmu to remove all (two) holes (Marc)
- Updating the guest's view of the pmu events before every vcpu run rather than
  vcpu load to avoid missing updates (Marc)

Thanks,
/fuad

[1] https://lore.kernel.org/all/20220509120330.3043773-1-tabba@google.com/
[2] https://lore.kernel.org/all/20220509095500.2408785-1-tabba@google.com/
[3] https://lore.kernel.org/linux-arm-kernel/20220408084052.3310931-1-tabba@google.com/

Fuad Tabba (4):
  KVM: arm64: Wrapper for getting pmu_events
  KVM: arm64: Repack struct kvm_pmu to reduce size
  KVM: arm64: Pass pmu events to hyp via vcpu
  KVM: arm64: Reenable pmu in Protected Mode

 arch/arm64/include/asm/kvm_host.h |  7 +-----
 arch/arm64/kvm/arm.c              | 15 ++++++++++++
 arch/arm64/kvm/hyp/nvhe/switch.c  | 20 +++++-----------
 arch/arm64/kvm/pmu-emul.c         |  3 +--
 arch/arm64/kvm/pmu.c              | 40 ++++++++++++++++++-------------
 include/kvm/arm_pmu.h             | 10 ++++++--
 6 files changed, 54 insertions(+), 41 deletions(-)


base-commit: 8c22fd2d4cfaab2ae3c5859496c894df58ab014b
-- 
2.36.0.512.ge40c2bad7a-goog


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linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

[PATCH v4 1/4] KVM: arm64: Wrapper for getting pmu_events

[Fuad Tabba]

Eases migrating away from using hyp data and simplifies the code.

No functional change intended.

Reviewed-by: Oliver Upton <oupton@google.com>
Signed-off-by: Fuad Tabba <tabba@google.com>
---
 arch/arm64/kvm/pmu.c | 42 ++++++++++++++++++++++++++----------------
 1 file changed, 26 insertions(+), 16 deletions(-)

diff --git a/arch/arm64/kvm/pmu.c b/arch/arm64/kvm/pmu.c
index 03a6c1f4a09a..4bd38ff34221 100644
--- a/arch/arm64/kvm/pmu.c
+++ b/arch/arm64/kvm/pmu.c
@@ -25,21 +25,31 @@ static bool kvm_pmu_switch_needed(struct perf_event_attr *attr)
 	return (attr->exclude_host != attr->exclude_guest);
 }
 
+static struct kvm_pmu_events *kvm_get_pmu_events(void)
+{
+	struct kvm_host_data *ctx = this_cpu_ptr_hyp_sym(kvm_host_data);
+
+	if (!ctx)
+		return NULL;
+
+	return &ctx->pmu_events;
+}
+
 /*
  * Add events to track that we may want to switch at guest entry/exit
  * time.
  */
 void kvm_set_pmu_events(u32 set, struct perf_event_attr *attr)
 {
-	struct kvm_host_data *ctx = this_cpu_ptr_hyp_sym(kvm_host_data);
+	struct kvm_pmu_events *pmu = kvm_get_pmu_events();
 
-	if (!kvm_arm_support_pmu_v3() || !ctx || !kvm_pmu_switch_needed(attr))
+	if (!kvm_arm_support_pmu_v3() || !pmu || !kvm_pmu_switch_needed(attr))
 		return;
 
 	if (!attr->exclude_host)
-		ctx->pmu_events.events_host |= set;
+		pmu->events_host |= set;
 	if (!attr->exclude_guest)
-		ctx->pmu_events.events_guest |= set;
+		pmu->events_guest |= set;
 }
 
 /*
@@ -47,13 +57,13 @@ void kvm_set_pmu_events(u32 set, struct perf_event_attr *attr)
  */
 void kvm_clr_pmu_events(u32 clr)
 {
-	struct kvm_host_data *ctx = this_cpu_ptr_hyp_sym(kvm_host_data);
+	struct kvm_pmu_events *pmu = kvm_get_pmu_events();
 
-	if (!kvm_arm_support_pmu_v3() || !ctx)
+	if (!kvm_arm_support_pmu_v3() || !pmu)
 		return;
 
-	ctx->pmu_events.events_host &= ~clr;
-	ctx->pmu_events.events_guest &= ~clr;
+	pmu->events_host &= ~clr;
+	pmu->events_guest &= ~clr;
 }
 
 #define PMEVTYPER_READ_CASE(idx)				\
@@ -169,16 +179,16 @@ static void kvm_vcpu_pmu_disable_el0(unsigned long events)
  */
 void kvm_vcpu_pmu_restore_guest(struct kvm_vcpu *vcpu)
 {
-	struct kvm_host_data *host;
+	struct kvm_pmu_events *pmu;
 	u32 events_guest, events_host;
 
 	if (!kvm_arm_support_pmu_v3() || !has_vhe())
 		return;
 
 	preempt_disable();
-	host = this_cpu_ptr_hyp_sym(kvm_host_data);
-	events_guest = host->pmu_events.events_guest;
-	events_host = host->pmu_events.events_host;
+	pmu = kvm_get_pmu_events();
+	events_guest = pmu->events_guest;
+	events_host = pmu->events_host;
 
 	kvm_vcpu_pmu_enable_el0(events_guest);
 	kvm_vcpu_pmu_disable_el0(events_host);
@@ -190,15 +200,15 @@ void kvm_vcpu_pmu_restore_guest(struct kvm_vcpu *vcpu)
  */
 void kvm_vcpu_pmu_restore_host(struct kvm_vcpu *vcpu)
 {
-	struct kvm_host_data *host;
+	struct kvm_pmu_events *pmu;
 	u32 events_guest, events_host;
 
 	if (!kvm_arm_support_pmu_v3() || !has_vhe())
 		return;
 
-	host = this_cpu_ptr_hyp_sym(kvm_host_data);
-	events_guest = host->pmu_events.events_guest;
-	events_host = host->pmu_events.events_host;
+	pmu = kvm_get_pmu_events();
+	events_guest = pmu->events_guest;
+	events_host = pmu->events_host;
 
 	kvm_vcpu_pmu_enable_el0(events_host);
 	kvm_vcpu_pmu_disable_el0(events_guest);
-- 
2.36.0.512.ge40c2bad7a-goog

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https://lists.cs.columbia.edu/mailman/listinfo/kvmarm

[PATCH v4 1/4] KVM: arm64: Wrapper for getting pmu_events

[Fuad Tabba]

Eases migrating away from using hyp data and simplifies the code.

No functional change intended.

Reviewed-by: Oliver Upton <oupton@google.com>
Signed-off-by: Fuad Tabba <tabba@google.com>
---
 arch/arm64/kvm/pmu.c | 42 ++++++++++++++++++++++++++----------------
 1 file changed, 26 insertions(+), 16 deletions(-)

diff --git a/arch/arm64/kvm/pmu.c b/arch/arm64/kvm/pmu.c
index 03a6c1f4a09a..4bd38ff34221 100644
--- a/arch/arm64/kvm/pmu.c
+++ b/arch/arm64/kvm/pmu.c
@@ -25,21 +25,31 @@ static bool kvm_pmu_switch_needed(struct perf_event_attr *attr)
 	return (attr->exclude_host != attr->exclude_guest);
 }
 
+static struct kvm_pmu_events *kvm_get_pmu_events(void)
+{
+	struct kvm_host_data *ctx = this_cpu_ptr_hyp_sym(kvm_host_data);
+
+	if (!ctx)
+		return NULL;
+
+	return &ctx->pmu_events;
+}
+
 /*
  * Add events to track that we may want to switch at guest entry/exit
  * time.
  */
 void kvm_set_pmu_events(u32 set, struct perf_event_attr *attr)
 {
-	struct kvm_host_data *ctx = this_cpu_ptr_hyp_sym(kvm_host_data);
+	struct kvm_pmu_events *pmu = kvm_get_pmu_events();
 
-	if (!kvm_arm_support_pmu_v3() || !ctx || !kvm_pmu_switch_needed(attr))
+	if (!kvm_arm_support_pmu_v3() || !pmu || !kvm_pmu_switch_needed(attr))
 		return;
 
 	if (!attr->exclude_host)
-		ctx->pmu_events.events_host |= set;
+		pmu->events_host |= set;
 	if (!attr->exclude_guest)
-		ctx->pmu_events.events_guest |= set;
+		pmu->events_guest |= set;
 }
 
 /*
@@ -47,13 +57,13 @@ void kvm_set_pmu_events(u32 set, struct perf_event_attr *attr)
  */
 void kvm_clr_pmu_events(u32 clr)
 {
-	struct kvm_host_data *ctx = this_cpu_ptr_hyp_sym(kvm_host_data);
+	struct kvm_pmu_events *pmu = kvm_get_pmu_events();
 
-	if (!kvm_arm_support_pmu_v3() || !ctx)
+	if (!kvm_arm_support_pmu_v3() || !pmu)
 		return;
 
-	ctx->pmu_events.events_host &= ~clr;
-	ctx->pmu_events.events_guest &= ~clr;
+	pmu->events_host &= ~clr;
+	pmu->events_guest &= ~clr;
 }
 
 #define PMEVTYPER_READ_CASE(idx)				\
@@ -169,16 +179,16 @@ static void kvm_vcpu_pmu_disable_el0(unsigned long events)
  */
 void kvm_vcpu_pmu_restore_guest(struct kvm_vcpu *vcpu)
 {
-	struct kvm_host_data *host;
+	struct kvm_pmu_events *pmu;
 	u32 events_guest, events_host;
 
 	if (!kvm_arm_support_pmu_v3() || !has_vhe())
 		return;
 
 	preempt_disable();
-	host = this_cpu_ptr_hyp_sym(kvm_host_data);
-	events_guest = host->pmu_events.events_guest;
-	events_host = host->pmu_events.events_host;
+	pmu = kvm_get_pmu_events();
+	events_guest = pmu->events_guest;
+	events_host = pmu->events_host;
 
 	kvm_vcpu_pmu_enable_el0(events_guest);
 	kvm_vcpu_pmu_disable_el0(events_host);
@@ -190,15 +200,15 @@ void kvm_vcpu_pmu_restore_guest(struct kvm_vcpu *vcpu)
  */
 void kvm_vcpu_pmu_restore_host(struct kvm_vcpu *vcpu)
 {
-	struct kvm_host_data *host;
+	struct kvm_pmu_events *pmu;
 	u32 events_guest, events_host;
 
 	if (!kvm_arm_support_pmu_v3() || !has_vhe())
 		return;
 
-	host = this_cpu_ptr_hyp_sym(kvm_host_data);
-	events_guest = host->pmu_events.events_guest;
-	events_host = host->pmu_events.events_host;
+	pmu = kvm_get_pmu_events();
+	events_guest = pmu->events_guest;
+	events_host = pmu->events_host;
 
 	kvm_vcpu_pmu_enable_el0(events_host);
 	kvm_vcpu_pmu_disable_el0(events_guest);
-- 
2.36.0.512.ge40c2bad7a-goog


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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

[PATCH v4 2/4] KVM: arm64: Repack struct kvm_pmu to reduce size

[Fuad Tabba]

struct kvm_pmu has 2 holes using 10 bytes. This is instantiated
in all vcpus, so it adds up. Repack the structures to remove the
holes.

No functional change intended.

Reviewed-by: Oliver Upton <oupton@google.com>
Signed-off-by: Fuad Tabba <tabba@google.com>
---
 include/kvm/arm_pmu.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
index 20193416d214..eaa8290b116f 100644
--- a/include/kvm/arm_pmu.h
+++ b/include/kvm/arm_pmu.h
@@ -21,12 +21,12 @@ struct kvm_pmc {
 };
 
 struct kvm_pmu {
-	int irq_num;
+	struct irq_work overflow_work;
 	struct kvm_pmc pmc[ARMV8_PMU_MAX_COUNTERS];
 	DECLARE_BITMAP(chained, ARMV8_PMU_MAX_COUNTER_PAIRS);
+	int irq_num;
 	bool created;
 	bool irq_level;
-	struct irq_work overflow_work;
 };
 
 struct arm_pmu_entry {
-- 
2.36.0.512.ge40c2bad7a-goog

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[PATCH v4 2/4] KVM: arm64: Repack struct kvm_pmu to reduce size

[Fuad Tabba]

struct kvm_pmu has 2 holes using 10 bytes. This is instantiated
in all vcpus, so it adds up. Repack the structures to remove the
holes.

No functional change intended.

Reviewed-by: Oliver Upton <oupton@google.com>
Signed-off-by: Fuad Tabba <tabba@google.com>
---
 include/kvm/arm_pmu.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
index 20193416d214..eaa8290b116f 100644
--- a/include/kvm/arm_pmu.h
+++ b/include/kvm/arm_pmu.h
@@ -21,12 +21,12 @@ struct kvm_pmc {
 };
 
 struct kvm_pmu {
-	int irq_num;
+	struct irq_work overflow_work;
 	struct kvm_pmc pmc[ARMV8_PMU_MAX_COUNTERS];
 	DECLARE_BITMAP(chained, ARMV8_PMU_MAX_COUNTER_PAIRS);
+	int irq_num;
 	bool created;
 	bool irq_level;
-	struct irq_work overflow_work;
 };
 
 struct arm_pmu_entry {
-- 
2.36.0.512.ge40c2bad7a-goog


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[PATCH v4 3/4] KVM: arm64: Pass pmu events to hyp via vcpu

[Fuad Tabba]

Instead of the host accessing hyp data directly, pass the pmu
events of the current cpu to hyp via the vcpu.

This adds 64 bits (in two fields) to the vcpu that need to be
synced before every vcpu run in nvhe and protected modes.
However, it isolates the hypervisor from the host, which allows
us to use pmu in protected mode in a subsequent patch.

No visible side effects in behavior intended.

Signed-off-by: Fuad Tabba <tabba@google.com>
---
 arch/arm64/include/asm/kvm_host.h |  7 +------
 arch/arm64/kvm/arm.c              | 15 +++++++++++++++
 arch/arm64/kvm/hyp/nvhe/switch.c  | 20 ++++++--------------
 arch/arm64/kvm/pmu.c              | 12 ++++--------
 include/kvm/arm_pmu.h             |  6 ++++++
 5 files changed, 32 insertions(+), 28 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index dfd360404dd8..835dd5ef630b 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -273,14 +273,8 @@ struct kvm_cpu_context {
 	struct kvm_vcpu *__hyp_running_vcpu;
 };
 
-struct kvm_pmu_events {
-	u32 events_host;
-	u32 events_guest;
-};
-
 struct kvm_host_data {
 	struct kvm_cpu_context host_ctxt;
-	struct kvm_pmu_events pmu_events;
 };
 
 struct kvm_host_psci_config {
@@ -821,6 +815,7 @@ void kvm_arch_vcpu_put_debug_state_flags(struct kvm_vcpu *vcpu);
 void kvm_set_pmu_events(u32 set, struct perf_event_attr *attr);
 void kvm_clr_pmu_events(u32 clr);
 
+struct kvm_pmu_events *kvm_get_pmu_events(void);
 void kvm_vcpu_pmu_restore_guest(struct kvm_vcpu *vcpu);
 void kvm_vcpu_pmu_restore_host(struct kvm_vcpu *vcpu);
 #else
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 2adb5832a756..86bcdb2a23a8 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -817,6 +817,19 @@ static int noinstr kvm_arm_vcpu_enter_exit(struct kvm_vcpu *vcpu)
 	return ret;
 }
 
+/*
+ * Updates the vcpu's view of the pmu events for this cpu.
+ * Must be called before every vcpu run after disabling interrupts, to ensure
+ * that an interrupt cannot fire and update the structure.
+ */
+static void kvm_pmu_update_vcpu_events(struct kvm_vcpu *vcpu)
+{
+	if (has_vhe() || !kvm_vcpu_has_pmu(vcpu))
+		return;
+
+	vcpu->arch.pmu.events = *kvm_get_pmu_events();
+}
+
 /**
  * kvm_arch_vcpu_ioctl_run - the main VCPU run function to execute guest code
  * @vcpu:	The VCPU pointer
@@ -882,6 +895,8 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 
 		kvm_vgic_flush_hwstate(vcpu);
 
+		kvm_pmu_update_vcpu_events(vcpu);
+
 		/*
 		 * Ensure we set mode to IN_GUEST_MODE after we disable
 		 * interrupts and before the final VCPU requests check.
diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c
index 0716163313d6..c61120ec8d1a 100644
--- a/arch/arm64/kvm/hyp/nvhe/switch.c
+++ b/arch/arm64/kvm/hyp/nvhe/switch.c
@@ -153,13 +153,9 @@ static void __hyp_vgic_restore_state(struct kvm_vcpu *vcpu)
 /*
  * Disable host events, enable guest events
  */
-static bool __pmu_switch_to_guest(struct kvm_cpu_context *host_ctxt)
+static bool __pmu_switch_to_guest(struct kvm_vcpu *vcpu)
 {
-	struct kvm_host_data *host;
-	struct kvm_pmu_events *pmu;
-
-	host = container_of(host_ctxt, struct kvm_host_data, host_ctxt);
-	pmu = &host->pmu_events;
+	struct kvm_pmu_events *pmu = &vcpu->arch.pmu.events;
 
 	if (pmu->events_host)
 		write_sysreg(pmu->events_host, pmcntenclr_el0);
@@ -173,13 +169,9 @@ static bool __pmu_switch_to_guest(struct kvm_cpu_context *host_ctxt)
 /*
  * Disable guest events, enable host events
  */
-static void __pmu_switch_to_host(struct kvm_cpu_context *host_ctxt)
+static void __pmu_switch_to_host(struct kvm_vcpu *vcpu)
 {
-	struct kvm_host_data *host;
-	struct kvm_pmu_events *pmu;
-
-	host = container_of(host_ctxt, struct kvm_host_data, host_ctxt);
-	pmu = &host->pmu_events;
+	struct kvm_pmu_events *pmu = &vcpu->arch.pmu.events;
 
 	if (pmu->events_guest)
 		write_sysreg(pmu->events_guest, pmcntenclr_el0);
@@ -304,7 +296,7 @@ int __kvm_vcpu_run(struct kvm_vcpu *vcpu)
 	host_ctxt->__hyp_running_vcpu = vcpu;
 	guest_ctxt = &vcpu->arch.ctxt;
 
-	pmu_switch_needed = __pmu_switch_to_guest(host_ctxt);
+	pmu_switch_needed = __pmu_switch_to_guest(vcpu);
 
 	__sysreg_save_state_nvhe(host_ctxt);
 	/*
@@ -366,7 +358,7 @@ int __kvm_vcpu_run(struct kvm_vcpu *vcpu)
 	__debug_restore_host_buffers_nvhe(vcpu);
 
 	if (pmu_switch_needed)
-		__pmu_switch_to_host(host_ctxt);
+		__pmu_switch_to_host(vcpu);
 
 	/* Returning to host will clear PSR.I, remask PMR if needed */
 	if (system_uses_irq_prio_masking())
diff --git a/arch/arm64/kvm/pmu.c b/arch/arm64/kvm/pmu.c
index 4bd38ff34221..7887133d15f0 100644
--- a/arch/arm64/kvm/pmu.c
+++ b/arch/arm64/kvm/pmu.c
@@ -5,7 +5,8 @@
  */
 #include <linux/kvm_host.h>
 #include <linux/perf_event.h>
-#include <asm/kvm_hyp.h>
+
+static DEFINE_PER_CPU(struct kvm_pmu_events, kvm_pmu_events);
 
 /*
  * Given the perf event attributes and system type, determine
@@ -25,14 +26,9 @@ static bool kvm_pmu_switch_needed(struct perf_event_attr *attr)
 	return (attr->exclude_host != attr->exclude_guest);
 }
 
-static struct kvm_pmu_events *kvm_get_pmu_events(void)
+struct kvm_pmu_events *kvm_get_pmu_events(void)
 {
-	struct kvm_host_data *ctx = this_cpu_ptr_hyp_sym(kvm_host_data);
-
-	if (!ctx)
-		return NULL;
-
-	return &ctx->pmu_events;
+	return this_cpu_ptr(&kvm_pmu_events);
 }
 
 /*
diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
index eaa8290b116f..35a0903cae32 100644
--- a/include/kvm/arm_pmu.h
+++ b/include/kvm/arm_pmu.h
@@ -20,8 +20,14 @@ struct kvm_pmc {
 	struct perf_event *perf_event;
 };
 
+struct kvm_pmu_events {
+	u32 events_host;
+	u32 events_guest;
+};
+
 struct kvm_pmu {
 	struct irq_work overflow_work;
+	struct kvm_pmu_events events;
 	struct kvm_pmc pmc[ARMV8_PMU_MAX_COUNTERS];
 	DECLARE_BITMAP(chained, ARMV8_PMU_MAX_COUNTER_PAIRS);
 	int irq_num;
-- 
2.36.0.512.ge40c2bad7a-goog

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[PATCH v4 3/4] KVM: arm64: Pass pmu events to hyp via vcpu

[Fuad Tabba]

Instead of the host accessing hyp data directly, pass the pmu
events of the current cpu to hyp via the vcpu.

This adds 64 bits (in two fields) to the vcpu that need to be
synced before every vcpu run in nvhe and protected modes.
However, it isolates the hypervisor from the host, which allows
us to use pmu in protected mode in a subsequent patch.

No visible side effects in behavior intended.

Signed-off-by: Fuad Tabba <tabba@google.com>
---
 arch/arm64/include/asm/kvm_host.h |  7 +------
 arch/arm64/kvm/arm.c              | 15 +++++++++++++++
 arch/arm64/kvm/hyp/nvhe/switch.c  | 20 ++++++--------------
 arch/arm64/kvm/pmu.c              | 12 ++++--------
 include/kvm/arm_pmu.h             |  6 ++++++
 5 files changed, 32 insertions(+), 28 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index dfd360404dd8..835dd5ef630b 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -273,14 +273,8 @@ struct kvm_cpu_context {
 	struct kvm_vcpu *__hyp_running_vcpu;
 };
 
-struct kvm_pmu_events {
-	u32 events_host;
-	u32 events_guest;
-};
-
 struct kvm_host_data {
 	struct kvm_cpu_context host_ctxt;
-	struct kvm_pmu_events pmu_events;
 };
 
 struct kvm_host_psci_config {
@@ -821,6 +815,7 @@ void kvm_arch_vcpu_put_debug_state_flags(struct kvm_vcpu *vcpu);
 void kvm_set_pmu_events(u32 set, struct perf_event_attr *attr);
 void kvm_clr_pmu_events(u32 clr);
 
+struct kvm_pmu_events *kvm_get_pmu_events(void);
 void kvm_vcpu_pmu_restore_guest(struct kvm_vcpu *vcpu);
 void kvm_vcpu_pmu_restore_host(struct kvm_vcpu *vcpu);
 #else
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 2adb5832a756..86bcdb2a23a8 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -817,6 +817,19 @@ static int noinstr kvm_arm_vcpu_enter_exit(struct kvm_vcpu *vcpu)
 	return ret;
 }
 
+/*
+ * Updates the vcpu's view of the pmu events for this cpu.
+ * Must be called before every vcpu run after disabling interrupts, to ensure
+ * that an interrupt cannot fire and update the structure.
+ */
+static void kvm_pmu_update_vcpu_events(struct kvm_vcpu *vcpu)
+{
+	if (has_vhe() || !kvm_vcpu_has_pmu(vcpu))
+		return;
+
+	vcpu->arch.pmu.events = *kvm_get_pmu_events();
+}
+
 /**
  * kvm_arch_vcpu_ioctl_run - the main VCPU run function to execute guest code
  * @vcpu:	The VCPU pointer
@@ -882,6 +895,8 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 
 		kvm_vgic_flush_hwstate(vcpu);
 
+		kvm_pmu_update_vcpu_events(vcpu);
+
 		/*
 		 * Ensure we set mode to IN_GUEST_MODE after we disable
 		 * interrupts and before the final VCPU requests check.
diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c
index 0716163313d6..c61120ec8d1a 100644
--- a/arch/arm64/kvm/hyp/nvhe/switch.c
+++ b/arch/arm64/kvm/hyp/nvhe/switch.c
@@ -153,13 +153,9 @@ static void __hyp_vgic_restore_state(struct kvm_vcpu *vcpu)
 /*
  * Disable host events, enable guest events
  */
-static bool __pmu_switch_to_guest(struct kvm_cpu_context *host_ctxt)
+static bool __pmu_switch_to_guest(struct kvm_vcpu *vcpu)
 {
-	struct kvm_host_data *host;
-	struct kvm_pmu_events *pmu;
-
-	host = container_of(host_ctxt, struct kvm_host_data, host_ctxt);
-	pmu = &host->pmu_events;
+	struct kvm_pmu_events *pmu = &vcpu->arch.pmu.events;
 
 	if (pmu->events_host)
 		write_sysreg(pmu->events_host, pmcntenclr_el0);
@@ -173,13 +169,9 @@ static bool __pmu_switch_to_guest(struct kvm_cpu_context *host_ctxt)
 /*
  * Disable guest events, enable host events
  */
-static void __pmu_switch_to_host(struct kvm_cpu_context *host_ctxt)
+static void __pmu_switch_to_host(struct kvm_vcpu *vcpu)
 {
-	struct kvm_host_data *host;
-	struct kvm_pmu_events *pmu;
-
-	host = container_of(host_ctxt, struct kvm_host_data, host_ctxt);
-	pmu = &host->pmu_events;
+	struct kvm_pmu_events *pmu = &vcpu->arch.pmu.events;
 
 	if (pmu->events_guest)
 		write_sysreg(pmu->events_guest, pmcntenclr_el0);
@@ -304,7 +296,7 @@ int __kvm_vcpu_run(struct kvm_vcpu *vcpu)
 	host_ctxt->__hyp_running_vcpu = vcpu;
 	guest_ctxt = &vcpu->arch.ctxt;
 
-	pmu_switch_needed = __pmu_switch_to_guest(host_ctxt);
+	pmu_switch_needed = __pmu_switch_to_guest(vcpu);
 
 	__sysreg_save_state_nvhe(host_ctxt);
 	/*
@@ -366,7 +358,7 @@ int __kvm_vcpu_run(struct kvm_vcpu *vcpu)
 	__debug_restore_host_buffers_nvhe(vcpu);
 
 	if (pmu_switch_needed)
-		__pmu_switch_to_host(host_ctxt);
+		__pmu_switch_to_host(vcpu);
 
 	/* Returning to host will clear PSR.I, remask PMR if needed */
 	if (system_uses_irq_prio_masking())
diff --git a/arch/arm64/kvm/pmu.c b/arch/arm64/kvm/pmu.c
index 4bd38ff34221..7887133d15f0 100644
--- a/arch/arm64/kvm/pmu.c
+++ b/arch/arm64/kvm/pmu.c
@@ -5,7 +5,8 @@
  */
 #include <linux/kvm_host.h>
 #include <linux/perf_event.h>
-#include <asm/kvm_hyp.h>
+
+static DEFINE_PER_CPU(struct kvm_pmu_events, kvm_pmu_events);
 
 /*
  * Given the perf event attributes and system type, determine
@@ -25,14 +26,9 @@ static bool kvm_pmu_switch_needed(struct perf_event_attr *attr)
 	return (attr->exclude_host != attr->exclude_guest);
 }
 
-static struct kvm_pmu_events *kvm_get_pmu_events(void)
+struct kvm_pmu_events *kvm_get_pmu_events(void)
 {
-	struct kvm_host_data *ctx = this_cpu_ptr_hyp_sym(kvm_host_data);
-
-	if (!ctx)
-		return NULL;
-
-	return &ctx->pmu_events;
+	return this_cpu_ptr(&kvm_pmu_events);
 }
 
 /*
diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
index eaa8290b116f..35a0903cae32 100644
--- a/include/kvm/arm_pmu.h
+++ b/include/kvm/arm_pmu.h
@@ -20,8 +20,14 @@ struct kvm_pmc {
 	struct perf_event *perf_event;
 };
 
+struct kvm_pmu_events {
+	u32 events_host;
+	u32 events_guest;
+};
+
 struct kvm_pmu {
 	struct irq_work overflow_work;
+	struct kvm_pmu_events events;
 	struct kvm_pmc pmc[ARMV8_PMU_MAX_COUNTERS];
 	DECLARE_BITMAP(chained, ARMV8_PMU_MAX_COUNTER_PAIRS);
 	int irq_num;
-- 
2.36.0.512.ge40c2bad7a-goog


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Re: [PATCH v4 3/4] KVM: arm64: Pass pmu events to hyp via vcpu

[Oliver Upton]

On Tue, May 10, 2022 at 09:57:09AM +0000, Fuad Tabba wrote:
> Instead of the host accessing hyp data directly, pass the pmu
> events of the current cpu to hyp via the vcpu.
> 
> This adds 64 bits (in two fields) to the vcpu that need to be
> synced before every vcpu run in nvhe and protected modes.
> However, it isolates the hypervisor from the host, which allows
> us to use pmu in protected mode in a subsequent patch.
> 
> No visible side effects in behavior intended.
> 
> Signed-off-by: Fuad Tabba <tabba@google.com>

Reviewed-by: Oliver Upton <oupton@google.com>
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Re: [PATCH v4 3/4] KVM: arm64: Pass pmu events to hyp via vcpu

[Oliver Upton]

On Tue, May 10, 2022 at 09:57:09AM +0000, Fuad Tabba wrote:
> Instead of the host accessing hyp data directly, pass the pmu
> events of the current cpu to hyp via the vcpu.
> 
> This adds 64 bits (in two fields) to the vcpu that need to be
> synced before every vcpu run in nvhe and protected modes.
> However, it isolates the hypervisor from the host, which allows
> us to use pmu in protected mode in a subsequent patch.
> 
> No visible side effects in behavior intended.
> 
> Signed-off-by: Fuad Tabba <tabba@google.com>

Reviewed-by: Oliver Upton <oupton@google.com>

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[PATCH v4 4/4] KVM: arm64: Reenable pmu in Protected Mode

[Fuad Tabba]

Now that the pmu code does not access hyp data, reenable it in
protected mode.

Once fully supported, protected VMs will not have pmu support,
since that could leak information. However, non-protected VMs in
protected mode should have pmu support if available.

Signed-off-by: Fuad Tabba <tabba@google.com>
---
 arch/arm64/kvm/pmu-emul.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index 3dc990ac4f44..11c43bed5f97 100644
--- a/arch/arm64/kvm/pmu-emul.c
+++ b/arch/arm64/kvm/pmu-emul.c
@@ -774,8 +774,7 @@ void kvm_host_pmu_init(struct arm_pmu *pmu)
 {
 	struct arm_pmu_entry *entry;
 
-	if (pmu->pmuver == 0 || pmu->pmuver == ID_AA64DFR0_PMUVER_IMP_DEF ||
-	    is_protected_kvm_enabled())
+	if (pmu->pmuver == 0 || pmu->pmuver == ID_AA64DFR0_PMUVER_IMP_DEF)
 		return;
 
 	mutex_lock(&arm_pmus_lock);
-- 
2.36.0.512.ge40c2bad7a-goog

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[PATCH v4 4/4] KVM: arm64: Reenable pmu in Protected Mode

[Fuad Tabba]

Now that the pmu code does not access hyp data, reenable it in
protected mode.

Once fully supported, protected VMs will not have pmu support,
since that could leak information. However, non-protected VMs in
protected mode should have pmu support if available.

Signed-off-by: Fuad Tabba <tabba@google.com>
---
 arch/arm64/kvm/pmu-emul.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index 3dc990ac4f44..11c43bed5f97 100644
--- a/arch/arm64/kvm/pmu-emul.c
+++ b/arch/arm64/kvm/pmu-emul.c
@@ -774,8 +774,7 @@ void kvm_host_pmu_init(struct arm_pmu *pmu)
 {
 	struct arm_pmu_entry *entry;
 
-	if (pmu->pmuver == 0 || pmu->pmuver == ID_AA64DFR0_PMUVER_IMP_DEF ||
-	    is_protected_kvm_enabled())
+	if (pmu->pmuver == 0 || pmu->pmuver == ID_AA64DFR0_PMUVER_IMP_DEF)
 		return;
 
 	mutex_lock(&arm_pmus_lock);
-- 
2.36.0.512.ge40c2bad7a-goog


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Re: [PATCH v4 4/4] KVM: arm64: Reenable pmu in Protected Mode

[Oliver Upton]

On Tue, May 10, 2022 at 09:57:10AM +0000, Fuad Tabba wrote:
> Now that the pmu code does not access hyp data, reenable it in
> protected mode.
> 
> Once fully supported, protected VMs will not have pmu support,
> since that could leak information. However, non-protected VMs in
> protected mode should have pmu support if available.
> 
> Signed-off-by: Fuad Tabba <tabba@google.com>

Reviewed-by: Oliver Upton <oupton@google.com>
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Re: [PATCH v4 4/4] KVM: arm64: Reenable pmu in Protected Mode

[Oliver Upton]

On Tue, May 10, 2022 at 09:57:10AM +0000, Fuad Tabba wrote:
> Now that the pmu code does not access hyp data, reenable it in
> protected mode.
> 
> Once fully supported, protected VMs will not have pmu support,
> since that could leak information. However, non-protected VMs in
> protected mode should have pmu support if available.
> 
> Signed-off-by: Fuad Tabba <tabba@google.com>

Reviewed-by: Oliver Upton <oupton@google.com>

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Re: [PATCH v4 0/4] KVM: arm64: Do not communicate host pmu event changes by accessing hyp data

[Marc Zyngier]

Hi Fuad,

On 2022-05-10 10:57, Fuad Tabba wrote:
> Hi,
> 
> This series changes the way KVM communicates host pmu event changes to 
> the
> hypervisor in nvhe and protected mode. Instead of accessing hyp data 
> directly
> from the host, the data is passed to hyp via the loaded vcpu. This 
> provides
> more isolation between the host and the hypervisor, and allows us to 
> use pmu in
> protected mode.
> 
> This series is based on kvmarm/next (8c22fd2d4cfa).

In the future, please don't do that. *Always* base your patches
on something stable (preferably an early -rc, as I usually start
pulling stuff in around -rc3).

kvmarm/next is a moving target, and basing things on top of it
results in an uncontrolled dependency chain. If your series depends
on something and makes it impossible to base your patches on an rc,
please state so (this isn't the case here).

Thanks,

         M.
-- 
Jazz is not dead. It just smells funny...
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Re: [PATCH v4 0/4] KVM: arm64: Do not communicate host pmu event changes by accessing hyp data

[Marc Zyngier]

Hi Fuad,

On 2022-05-10 10:57, Fuad Tabba wrote:
> Hi,
> 
> This series changes the way KVM communicates host pmu event changes to 
> the
> hypervisor in nvhe and protected mode. Instead of accessing hyp data 
> directly
> from the host, the data is passed to hyp via the loaded vcpu. This 
> provides
> more isolation between the host and the hypervisor, and allows us to 
> use pmu in
> protected mode.
> 
> This series is based on kvmarm/next (8c22fd2d4cfa).

In the future, please don't do that. *Always* base your patches
on something stable (preferably an early -rc, as I usually start
pulling stuff in around -rc3).

kvmarm/next is a moving target, and basing things on top of it
results in an uncontrolled dependency chain. If your series depends
on something and makes it impossible to base your patches on an rc,
please state so (this isn't the case here).

Thanks,

         M.
-- 
Jazz is not dead. It just smells funny...

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Re: [PATCH v4 0/4] KVM: arm64: Do not communicate host pmu event changes by accessing hyp data

[Marc Zyngier]

On Tue, 10 May 2022 09:57:06 +0000, Fuad Tabba wrote:
> This series changes the way KVM communicates host pmu event changes to the
> hypervisor in nvhe and protected mode. Instead of accessing hyp data directly
> from the host, the data is passed to hyp via the loaded vcpu. This provides
> more isolation between the host and the hypervisor, and allows us to use pmu in
> protected mode.
> 
> This series is based on kvmarm/next (8c22fd2d4cfa).
> 
> [...]

Applied to next, thanks!

[1/4] KVM: arm64: Wrapper for getting pmu_events
      commit: 3cb8a091a7016be0ee5420ff6c1928972e3ce23e
[2/4] KVM: arm64: Repack struct kvm_pmu to reduce size
      commit: e987a4c60f9755b2f7a19bf1b5ef2eb74c90579b
[3/4] KVM: arm64: Pass pmu events to hyp via vcpu
      commit: 84d751a019a9792f5b4884e1d598b603c360ec22
[4/4] KVM: arm64: Reenable pmu in Protected Mode
      commit: 722625c6f4c5b6a9953d6af04c7bb1a6e12830b3

Cheers,

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


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Re: [PATCH v4 0/4] KVM: arm64: Do not communicate host pmu event changes by accessing hyp data

[Marc Zyngier]

On Tue, 10 May 2022 09:57:06 +0000, Fuad Tabba wrote:
> This series changes the way KVM communicates host pmu event changes to the
> hypervisor in nvhe and protected mode. Instead of accessing hyp data directly
> from the host, the data is passed to hyp via the loaded vcpu. This provides
> more isolation between the host and the hypervisor, and allows us to use pmu in
> protected mode.
> 
> This series is based on kvmarm/next (8c22fd2d4cfa).
> 
> [...]

Applied to next, thanks!

[1/4] KVM: arm64: Wrapper for getting pmu_events
      commit: 3cb8a091a7016be0ee5420ff6c1928972e3ce23e
[2/4] KVM: arm64: Repack struct kvm_pmu to reduce size
      commit: e987a4c60f9755b2f7a19bf1b5ef2eb74c90579b
[3/4] KVM: arm64: Pass pmu events to hyp via vcpu
      commit: 84d751a019a9792f5b4884e1d598b603c360ec22
[4/4] KVM: arm64: Reenable pmu in Protected Mode
      commit: 722625c6f4c5b6a9953d6af04c7bb1a6e12830b3

Cheers,

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



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