[GIT PULL] KVM/arm updates for 4.18-rc2

[GIT PULL] KVM/arm updates for 4.18-rc2

[Marc Zyngier]

Radim, Paolo,

This is the first batch of fixes for 4.18, mostly dealing with the
fallout from Dave's lazy FPSIMD handling. We also have the disabling
of the compat interface on arm64 (it never had it the first place),
and a relaxation on the alignment of the GICv3 compatibility
interface.

Please pull.

	M.

The following changes since commit ce397d215ccd07b8ae3f71db689aedb85d56ab40:

  Linux 4.18-rc1 (2018-06-17 08:04:49 +0900)

are available in the Git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm.git tags/kvmarm-fixes-for-4.18-1

for you to fetch changes up to 37b65db85f9b2fc98267eee4a18d7506492e6e8c:

  KVM: arm64: Prevent KVM_COMPAT from being selected (2018-06-21 17:17:50 +0100)

----------------------------------------------------------------
KVM/arm fixes for 4.18, take #1

- Lazy FPSIMD switching fixes
- Really disable compat ioctls on architectures that don't want it
- Disable compat on arm64 (it was never implemented...)
- Rely on architectural requirements for GICV on GICv3
- Detect bad alignments in unmap_stage2_range

----------------------------------------------------------------
Ard Biesheuvel (1):
      KVM: arm/arm64: Drop resource size check for GICV window

Dave Martin (3):
      KVM: arm64: Don't mask softirq with IRQs disabled in vcpu_put()
      KVM: arm64/sve: Fix SVE trap restoration for non-current tasks
      KVM: arm64: Avoid mistaken attempts to save SVE state for vcpus

Jia He (1):
      KVM: arm/arm64: add WARN_ON if size is not PAGE_SIZE aligned in unmap_stage2_range

Marc Zyngier (2):
      KVM: Enforce error in ioctl for compat tasks when !KVM_COMPAT
      KVM: arm64: Prevent KVM_COMPAT from being selected

Mark Rutland (1):
      arm64: Introduce sysreg_clear_set()

 arch/arm64/include/asm/kvm_host.h |  1 +
 arch/arm64/include/asm/sysreg.h   | 11 +++++++++++
 arch/arm64/kvm/fpsimd.c           | 36 +++++++++++++++++++++++++++---------
 virt/kvm/Kconfig                  |  2 +-
 virt/kvm/arm/mmu.c                |  2 ++
 virt/kvm/arm/vgic/vgic-v3.c       |  5 -----
 virt/kvm/kvm_main.c               | 19 +++++++++----------
 7 files changed, 51 insertions(+), 25 deletions(-)

[GIT PULL] KVM/arm updates for 4.18-rc2

[Marc Zyngier]

Radim, Paolo,

This is the first batch of fixes for 4.18, mostly dealing with the
fallout from Dave's lazy FPSIMD handling. We also have the disabling
of the compat interface on arm64 (it never had it the first place),
and a relaxation on the alignment of the GICv3 compatibility
interface.

Please pull.

	M.

The following changes since commit ce397d215ccd07b8ae3f71db689aedb85d56ab40:

  Linux 4.18-rc1 (2018-06-17 08:04:49 +0900)

are available in the Git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm.git tags/kvmarm-fixes-for-4.18-1

for you to fetch changes up to 37b65db85f9b2fc98267eee4a18d7506492e6e8c:

  KVM: arm64: Prevent KVM_COMPAT from being selected (2018-06-21 17:17:50 +0100)

----------------------------------------------------------------
KVM/arm fixes for 4.18, take #1

- Lazy FPSIMD switching fixes
- Really disable compat ioctls on architectures that don't want it
- Disable compat on arm64 (it was never implemented...)
- Rely on architectural requirements for GICV on GICv3
- Detect bad alignments in unmap_stage2_range

----------------------------------------------------------------
Ard Biesheuvel (1):
      KVM: arm/arm64: Drop resource size check for GICV window

Dave Martin (3):
      KVM: arm64: Don't mask softirq with IRQs disabled in vcpu_put()
      KVM: arm64/sve: Fix SVE trap restoration for non-current tasks
      KVM: arm64: Avoid mistaken attempts to save SVE state for vcpus

Jia He (1):
      KVM: arm/arm64: add WARN_ON if size is not PAGE_SIZE aligned in unmap_stage2_range

Marc Zyngier (2):
      KVM: Enforce error in ioctl for compat tasks when !KVM_COMPAT
      KVM: arm64: Prevent KVM_COMPAT from being selected

Mark Rutland (1):
      arm64: Introduce sysreg_clear_set()

 arch/arm64/include/asm/kvm_host.h |  1 +
 arch/arm64/include/asm/sysreg.h   | 11 +++++++++++
 arch/arm64/kvm/fpsimd.c           | 36 +++++++++++++++++++++++++++---------
 virt/kvm/Kconfig                  |  2 +-
 virt/kvm/arm/mmu.c                |  2 ++
 virt/kvm/arm/vgic/vgic-v3.c       |  5 -----
 virt/kvm/kvm_main.c               | 19 +++++++++----------
 7 files changed, 51 insertions(+), 25 deletions(-)

[PATCH 1/8] KVM: arm/arm64: Drop resource size check for GICV window

[Marc Zyngier]

From: Ard Biesheuvel <ard.biesheuvel@linaro.org>

When booting a 64 KB pages kernel on a ACPI GICv3 system that
implements support for v2 emulation, the following warning is
produced

  GICV size 0x2000 not a multiple of page size 0x10000

and support for v2 emulation is disabled, preventing GICv2 VMs
from being able to run on such hosts.

The reason is that vgic_v3_probe() performs a sanity check on the
size of the window (it should be a multiple of the page size),
while the ACPI MADT parsing code hardcodes the size of the window
to 8 KB. This makes sense, considering that ACPI does not bother
to describe the size in the first place, under the assumption that
platforms implementing ACPI will follow the architecture and not
put anything else in the same 64 KB window.

So let's just drop the sanity check altogether, and assume that
the window is at least 64 KB in size.

Fixes: 909777324588 ("KVM: arm/arm64: vgic-new: vgic_init: implement kvm_vgic_hyp_init")
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
 virt/kvm/arm/vgic/vgic-v3.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/virt/kvm/arm/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c
index ff7dc890941a..cdce653e3c47 100644
--- a/virt/kvm/arm/vgic/vgic-v3.c
+++ b/virt/kvm/arm/vgic/vgic-v3.c
@@ -617,11 +617,6 @@ int vgic_v3_probe(const struct gic_kvm_info *info)
 		pr_warn("GICV physical address 0x%llx not page aligned\n",
 			(unsigned long long)info->vcpu.start);
 		kvm_vgic_global_state.vcpu_base = 0;
-	} else if (!PAGE_ALIGNED(resource_size(&info->vcpu))) {
-		pr_warn("GICV size 0x%llx not a multiple of page size 0x%lx\n",
-			(unsigned long long)resource_size(&info->vcpu),
-			PAGE_SIZE);
-		kvm_vgic_global_state.vcpu_base = 0;
 	} else {
 		kvm_vgic_global_state.vcpu_base = info->vcpu.start;
 		kvm_vgic_global_state.can_emulate_gicv2 = true;
-- 
2.17.1

[PATCH 1/8] KVM: arm/arm64: Drop resource size check for GICV window

[Marc Zyngier]

From: Ard Biesheuvel <ard.biesheuvel@linaro.org>

When booting a 64 KB pages kernel on a ACPI GICv3 system that
implements support for v2 emulation, the following warning is
produced

  GICV size 0x2000 not a multiple of page size 0x10000

and support for v2 emulation is disabled, preventing GICv2 VMs
from being able to run on such hosts.

The reason is that vgic_v3_probe() performs a sanity check on the
size of the window (it should be a multiple of the page size),
while the ACPI MADT parsing code hardcodes the size of the window
to 8 KB. This makes sense, considering that ACPI does not bother
to describe the size in the first place, under the assumption that
platforms implementing ACPI will follow the architecture and not
put anything else in the same 64 KB window.

So let's just drop the sanity check altogether, and assume that
the window is at least 64 KB in size.

Fixes: 909777324588 ("KVM: arm/arm64: vgic-new: vgic_init: implement kvm_vgic_hyp_init")
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
 virt/kvm/arm/vgic/vgic-v3.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/virt/kvm/arm/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c
index ff7dc890941a..cdce653e3c47 100644
--- a/virt/kvm/arm/vgic/vgic-v3.c
+++ b/virt/kvm/arm/vgic/vgic-v3.c
@@ -617,11 +617,6 @@ int vgic_v3_probe(const struct gic_kvm_info *info)
 		pr_warn("GICV physical address 0x%llx not page aligned\n",
 			(unsigned long long)info->vcpu.start);
 		kvm_vgic_global_state.vcpu_base = 0;
-	} else if (!PAGE_ALIGNED(resource_size(&info->vcpu))) {
-		pr_warn("GICV size 0x%llx not a multiple of page size 0x%lx\n",
-			(unsigned long long)resource_size(&info->vcpu),
-			PAGE_SIZE);
-		kvm_vgic_global_state.vcpu_base = 0;
 	} else {
 		kvm_vgic_global_state.vcpu_base = info->vcpu.start;
 		kvm_vgic_global_state.can_emulate_gicv2 = true;
-- 
2.17.1

[PATCH 2/8] arm64: Introduce sysreg_clear_set()

[Marc Zyngier]

From: Mark Rutland <mark.rutland@arm.com>

Currently we have a couple of helpers to manipulate bits in particular
sysregs:

 * config_sctlr_el1(u32 clear, u32 set)

 * change_cpacr(u64 val, u64 mask)

The parameters of these differ in naming convention, order, and size,
which is unfortunate. They also differ slightly in behaviour, as
change_cpacr() skips the sysreg write if the bits are unchanged, which
is a useful optimization when sysreg writes are expensive.

Before we gain yet another sysreg manipulation function, let's
unify these with a common helper, providing a consistent order for
clear/set operands, and the write skipping behaviour from
change_cpacr(). Code will be migrated to the new helper in subsequent
patches.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Dave Martin <dave.martin@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
 arch/arm64/include/asm/sysreg.h | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
index 6171178075dc..a8f84812c6e8 100644
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -728,6 +728,17 @@ asm(
 	asm volatile("msr_s " __stringify(r) ", %x0" : : "rZ" (__val));	\
 } while (0)
 
+/*
+ * Modify bits in a sysreg. Bits in the clear mask are zeroed, then bits in the
+ * set mask are set. Other bits are left as-is.
+ */
+#define sysreg_clear_set(sysreg, clear, set) do {			\
+	u64 __scs_val = read_sysreg(sysreg);				\
+	u64 __scs_new = (__scs_val & ~(u64)(clear)) | (set);		\
+	if (__scs_new != __scs_val)					\
+		write_sysreg(__scs_new, sysreg);			\
+} while (0)
+
 static inline void config_sctlr_el1(u32 clear, u32 set)
 {
 	u32 val;
-- 
2.17.1

[PATCH 2/8] arm64: Introduce sysreg_clear_set()

[Marc Zyngier]

From: Mark Rutland <mark.rutland@arm.com>

Currently we have a couple of helpers to manipulate bits in particular
sysregs:

 * config_sctlr_el1(u32 clear, u32 set)

 * change_cpacr(u64 val, u64 mask)

The parameters of these differ in naming convention, order, and size,
which is unfortunate. They also differ slightly in behaviour, as
change_cpacr() skips the sysreg write if the bits are unchanged, which
is a useful optimization when sysreg writes are expensive.

Before we gain yet another sysreg manipulation function, let's
unify these with a common helper, providing a consistent order for
clear/set operands, and the write skipping behaviour from
change_cpacr(). Code will be migrated to the new helper in subsequent
patches.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Dave Martin <dave.martin@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
 arch/arm64/include/asm/sysreg.h | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
index 6171178075dc..a8f84812c6e8 100644
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -728,6 +728,17 @@ asm(
 	asm volatile("msr_s " __stringify(r) ", %x0" : : "rZ" (__val));	\
 } while (0)
 
+/*
+ * Modify bits in a sysreg. Bits in the clear mask are zeroed, then bits in the
+ * set mask are set. Other bits are left as-is.
+ */
+#define sysreg_clear_set(sysreg, clear, set) do {			\
+	u64 __scs_val = read_sysreg(sysreg);				\
+	u64 __scs_new = (__scs_val & ~(u64)(clear)) | (set);		\
+	if (__scs_new != __scs_val)					\
+		write_sysreg(__scs_new, sysreg);			\
+} while (0)
+
 static inline void config_sctlr_el1(u32 clear, u32 set)
 {
 	u32 val;
-- 
2.17.1

[PATCH 3/8] KVM: arm64: Don't mask softirq with IRQs disabled in vcpu_put()

[Marc Zyngier]

From: Dave Martin <Dave.Martin@arm.com>

Commit e6b673b ("KVM: arm64: Optimise FPSIMD handling to reduce
guest/host thrashing") introduces a specific helper
kvm_arch_vcpu_put_fp() for saving the vcpu FPSIMD state during
vcpu_put().

This function uses local_bh_disable()/_enable() to protect the
FPSIMD context manipulation from interruption by softirqs.

This approach is not correct, because vcpu_put() can be invoked
either from the KVM host vcpu thread (when exiting the vcpu run
loop), or via a preempt notifier.  In the former case, only
preemption is disabled.  In the latter case, the function is called
from inside __schedule(), which means that IRQs are disabled.

Use of local_bh_disable()/_enable() with IRQs disabled is considerd
an error, resulting in lockdep splats while running VMs if lockdep
is enabled.

This patch disables IRQs instead of attempting to disable softirqs,
avoiding the problem of calling local_bh_enable() with IRQs
disabled in the __schedule() path.  This creates an additional
interrupt blackout during vcpu run loop exit, but this is the rare
case and the blackout latency is still less than that of
__schedule().

Fixes: e6b673b741ea ("KVM: arm64: Optimise FPSIMD handling to reduce guest/host thrashing")
Reported-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
 arch/arm64/kvm/fpsimd.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kvm/fpsimd.c b/arch/arm64/kvm/fpsimd.c
index dc6ecfa5a2d2..f9d09318b8db 100644
--- a/arch/arm64/kvm/fpsimd.c
+++ b/arch/arm64/kvm/fpsimd.c
@@ -5,7 +5,7 @@
  * Copyright 2018 Arm Limited
  * Author: Dave Martin <Dave.Martin@arm.com>
  */
-#include <linux/bottom_half.h>
+#include <linux/irqflags.h>
 #include <linux/sched.h>
 #include <linux/thread_info.h>
 #include <linux/kvm_host.h>
@@ -92,7 +92,9 @@ void kvm_arch_vcpu_ctxsync_fp(struct kvm_vcpu *vcpu)
  */
 void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu)
 {
-	local_bh_disable();
+	unsigned long flags;
+
+	local_irq_save(flags);
 
 	update_thread_flag(TIF_SVE,
 			   vcpu->arch.flags & KVM_ARM64_HOST_SVE_IN_USE);
@@ -106,5 +108,5 @@ void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu)
 		fpsimd_bind_task_to_cpu();
 	}
 
-	local_bh_enable();
+	local_irq_restore(flags);
 }
-- 
2.17.1

[PATCH 3/8] KVM: arm64: Don't mask softirq with IRQs disabled in vcpu_put()

[Marc Zyngier]

From: Dave Martin <Dave.Martin@arm.com>

Commit e6b673b ("KVM: arm64: Optimise FPSIMD handling to reduce
guest/host thrashing") introduces a specific helper
kvm_arch_vcpu_put_fp() for saving the vcpu FPSIMD state during
vcpu_put().

This function uses local_bh_disable()/_enable() to protect the
FPSIMD context manipulation from interruption by softirqs.

This approach is not correct, because vcpu_put() can be invoked
either from the KVM host vcpu thread (when exiting the vcpu run
loop), or via a preempt notifier.  In the former case, only
preemption is disabled.  In the latter case, the function is called
from inside __schedule(), which means that IRQs are disabled.

Use of local_bh_disable()/_enable() with IRQs disabled is considerd
an error, resulting in lockdep splats while running VMs if lockdep
is enabled.

This patch disables IRQs instead of attempting to disable softirqs,
avoiding the problem of calling local_bh_enable() with IRQs
disabled in the __schedule() path.  This creates an additional
interrupt blackout during vcpu run loop exit, but this is the rare
case and the blackout latency is still less than that of
__schedule().

Fixes: e6b673b741ea ("KVM: arm64: Optimise FPSIMD handling to reduce guest/host thrashing")
Reported-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
 arch/arm64/kvm/fpsimd.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kvm/fpsimd.c b/arch/arm64/kvm/fpsimd.c
index dc6ecfa5a2d2..f9d09318b8db 100644
--- a/arch/arm64/kvm/fpsimd.c
+++ b/arch/arm64/kvm/fpsimd.c
@@ -5,7 +5,7 @@
  * Copyright 2018 Arm Limited
  * Author: Dave Martin <Dave.Martin@arm.com>
  */
-#include <linux/bottom_half.h>
+#include <linux/irqflags.h>
 #include <linux/sched.h>
 #include <linux/thread_info.h>
 #include <linux/kvm_host.h>
@@ -92,7 +92,9 @@ void kvm_arch_vcpu_ctxsync_fp(struct kvm_vcpu *vcpu)
  */
 void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu)
 {
-	local_bh_disable();
+	unsigned long flags;
+
+	local_irq_save(flags);
 
 	update_thread_flag(TIF_SVE,
 			   vcpu->arch.flags & KVM_ARM64_HOST_SVE_IN_USE);
@@ -106,5 +108,5 @@ void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu)
 		fpsimd_bind_task_to_cpu();
 	}
 
-	local_bh_enable();
+	local_irq_restore(flags);
 }
-- 
2.17.1

[PATCH 4/8] KVM: arm64/sve: Fix SVE trap restoration for non-current tasks

[Marc Zyngier]

From: Dave Martin <Dave.Martin@arm.com>

Commit e6b673b ("KVM: arm64: Optimise FPSIMD handling to reduce
guest/host thrashing") attempts to restore the configuration of
userspace SVE trapping via a call to fpsimd_bind_task_to_cpu(), but
the logic for determining when to do this is not correct.

The patch makes the errnoenous assumption that the only task that
may try to enter userspace with the currently loaded FPSIMD/SVE
register content is current.  This may not be the case however:  if
some other user task T is scheduled on the CPU during the execution
of the KVM run loop, and the vcpu does not try to use the registers
in the meantime, then T's state may be left there intact.  If T
happens to be the next task to enter userspace on this CPU then the
hooks for reloading the register state and configuring traps will
be skipped.

(Also, current never has SVE state at this point anyway and should
always have the trap enabled, as a side-effect of the ioctl()
syscall needed to reach the KVM run loop in the first place.)

This patch instead restores the state of the EL0 trap from the
state observed at the most recent vcpu_load(), ensuring that the
trap is set correctly for the loaded context (if any).

Fixes: e6b673b741ea ("KVM: arm64: Optimise FPSIMD handling to reduce guest/host thrashing")
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
 arch/arm64/include/asm/kvm_host.h |  1 +
 arch/arm64/kvm/fpsimd.c           | 24 ++++++++++++++++++++----
 2 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index fda9a8ca48be..fe8777b12f86 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -306,6 +306,7 @@ struct kvm_vcpu_arch {
 #define KVM_ARM64_FP_ENABLED		(1 << 1) /* guest FP regs loaded */
 #define KVM_ARM64_FP_HOST		(1 << 2) /* host FP regs loaded */
 #define KVM_ARM64_HOST_SVE_IN_USE	(1 << 3) /* backup for host TIF_SVE */
+#define KVM_ARM64_HOST_SVE_ENABLED	(1 << 4) /* SVE enabled for EL0 */
 
 #define vcpu_gp_regs(v)		(&(v)->arch.ctxt.gp_regs)
 
diff --git a/arch/arm64/kvm/fpsimd.c b/arch/arm64/kvm/fpsimd.c
index f9d09318b8db..98d19d1afa50 100644
--- a/arch/arm64/kvm/fpsimd.c
+++ b/arch/arm64/kvm/fpsimd.c
@@ -12,6 +12,7 @@
 #include <asm/kvm_asm.h>
 #include <asm/kvm_host.h>
 #include <asm/kvm_mmu.h>
+#include <asm/sysreg.h>
 
 /*
  * Called on entry to KVM_RUN unless this vcpu previously ran at least
@@ -61,10 +62,16 @@ void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu)
 {
 	BUG_ON(!current->mm);
 
-	vcpu->arch.flags &= ~(KVM_ARM64_FP_ENABLED | KVM_ARM64_HOST_SVE_IN_USE);
+	vcpu->arch.flags &= ~(KVM_ARM64_FP_ENABLED |
+			      KVM_ARM64_HOST_SVE_IN_USE |
+			      KVM_ARM64_HOST_SVE_ENABLED);
 	vcpu->arch.flags |= KVM_ARM64_FP_HOST;
+
 	if (test_thread_flag(TIF_SVE))
 		vcpu->arch.flags |= KVM_ARM64_HOST_SVE_IN_USE;
+
+	if (read_sysreg(cpacr_el1) & CPACR_EL1_ZEN_EL0EN)
+		vcpu->arch.flags |= KVM_ARM64_HOST_SVE_ENABLED;
 }
 
 /*
@@ -103,9 +110,18 @@ void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu)
 		/* Clean guest FP state to memory and invalidate cpu view */
 		fpsimd_save();
 		fpsimd_flush_cpu_state();
-	} else if (!test_thread_flag(TIF_FOREIGN_FPSTATE)) {
-		/* Ensure user trap controls are correctly restored */
-		fpsimd_bind_task_to_cpu();
+	} else if (system_supports_sve()) {
+		/*
+		 * The FPSIMD/SVE state in the CPU has not been touched, and we
+		 * have SVE (and VHE): CPACR_EL1 (alias CPTR_EL2) has been
+		 * reset to CPACR_EL1_DEFAULT by the Hyp code, disabling SVE
+		 * for EL0.  To avoid spurious traps, restore the trap state
+		 * seen by kvm_arch_vcpu_load_fp():
+		 */
+		if (vcpu->arch.flags & KVM_ARM64_HOST_SVE_ENABLED)
+			sysreg_clear_set(CPACR_EL1, 0, CPACR_EL1_ZEN_EL0EN);
+		else
+			sysreg_clear_set(CPACR_EL1, CPACR_EL1_ZEN_EL0EN, 0);
 	}
 
 	local_irq_restore(flags);
-- 
2.17.1

[PATCH 4/8] KVM: arm64/sve: Fix SVE trap restoration for non-current tasks

[Marc Zyngier]

From: Dave Martin <Dave.Martin@arm.com>

Commit e6b673b ("KVM: arm64: Optimise FPSIMD handling to reduce
guest/host thrashing") attempts to restore the configuration of
userspace SVE trapping via a call to fpsimd_bind_task_to_cpu(), but
the logic for determining when to do this is not correct.

The patch makes the errnoenous assumption that the only task that
may try to enter userspace with the currently loaded FPSIMD/SVE
register content is current.  This may not be the case however:  if
some other user task T is scheduled on the CPU during the execution
of the KVM run loop, and the vcpu does not try to use the registers
in the meantime, then T's state may be left there intact.  If T
happens to be the next task to enter userspace on this CPU then the
hooks for reloading the register state and configuring traps will
be skipped.

(Also, current never has SVE state at this point anyway and should
always have the trap enabled, as a side-effect of the ioctl()
syscall needed to reach the KVM run loop in the first place.)

This patch instead restores the state of the EL0 trap from the
state observed at the most recent vcpu_load(), ensuring that the
trap is set correctly for the loaded context (if any).

Fixes: e6b673b741ea ("KVM: arm64: Optimise FPSIMD handling to reduce guest/host thrashing")
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
 arch/arm64/include/asm/kvm_host.h |  1 +
 arch/arm64/kvm/fpsimd.c           | 24 ++++++++++++++++++++----
 2 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index fda9a8ca48be..fe8777b12f86 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -306,6 +306,7 @@ struct kvm_vcpu_arch {
 #define KVM_ARM64_FP_ENABLED		(1 << 1) /* guest FP regs loaded */
 #define KVM_ARM64_FP_HOST		(1 << 2) /* host FP regs loaded */
 #define KVM_ARM64_HOST_SVE_IN_USE	(1 << 3) /* backup for host TIF_SVE */
+#define KVM_ARM64_HOST_SVE_ENABLED	(1 << 4) /* SVE enabled for EL0 */
 
 #define vcpu_gp_regs(v)		(&(v)->arch.ctxt.gp_regs)
 
diff --git a/arch/arm64/kvm/fpsimd.c b/arch/arm64/kvm/fpsimd.c
index f9d09318b8db..98d19d1afa50 100644
--- a/arch/arm64/kvm/fpsimd.c
+++ b/arch/arm64/kvm/fpsimd.c
@@ -12,6 +12,7 @@
 #include <asm/kvm_asm.h>
 #include <asm/kvm_host.h>
 #include <asm/kvm_mmu.h>
+#include <asm/sysreg.h>
 
 /*
  * Called on entry to KVM_RUN unless this vcpu previously ran at least
@@ -61,10 +62,16 @@ void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu)
 {
 	BUG_ON(!current->mm);
 
-	vcpu->arch.flags &= ~(KVM_ARM64_FP_ENABLED | KVM_ARM64_HOST_SVE_IN_USE);
+	vcpu->arch.flags &= ~(KVM_ARM64_FP_ENABLED |
+			      KVM_ARM64_HOST_SVE_IN_USE |
+			      KVM_ARM64_HOST_SVE_ENABLED);
 	vcpu->arch.flags |= KVM_ARM64_FP_HOST;
+
 	if (test_thread_flag(TIF_SVE))
 		vcpu->arch.flags |= KVM_ARM64_HOST_SVE_IN_USE;
+
+	if (read_sysreg(cpacr_el1) & CPACR_EL1_ZEN_EL0EN)
+		vcpu->arch.flags |= KVM_ARM64_HOST_SVE_ENABLED;
 }
 
 /*
@@ -103,9 +110,18 @@ void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu)
 		/* Clean guest FP state to memory and invalidate cpu view */
 		fpsimd_save();
 		fpsimd_flush_cpu_state();
-	} else if (!test_thread_flag(TIF_FOREIGN_FPSTATE)) {
-		/* Ensure user trap controls are correctly restored */
-		fpsimd_bind_task_to_cpu();
+	} else if (system_supports_sve()) {
+		/*
+		 * The FPSIMD/SVE state in the CPU has not been touched, and we
+		 * have SVE (and VHE): CPACR_EL1 (alias CPTR_EL2) has been
+		 * reset to CPACR_EL1_DEFAULT by the Hyp code, disabling SVE
+		 * for EL0.  To avoid spurious traps, restore the trap state
+		 * seen by kvm_arch_vcpu_load_fp():
+		 */
+		if (vcpu->arch.flags & KVM_ARM64_HOST_SVE_ENABLED)
+			sysreg_clear_set(CPACR_EL1, 0, CPACR_EL1_ZEN_EL0EN);
+		else
+			sysreg_clear_set(CPACR_EL1, CPACR_EL1_ZEN_EL0EN, 0);
 	}
 
 	local_irq_restore(flags);
-- 
2.17.1

[PATCH 5/8] KVM: arm64: Avoid mistaken attempts to save SVE state for vcpus

[Marc Zyngier]

From: Dave Martin <Dave.Martin@arm.com>

Commit e6b673b ("KVM: arm64: Optimise FPSIMD handling to reduce
guest/host thrashing") uses fpsimd_save() to save the FPSIMD state
for a vcpu when scheduling the vcpu out.  However, currently
current's value of TIF_SVE is restored before calling fpsimd_save()
which means that fpsimd_save() may erroneously attempt to save SVE
state from the vcpu.  This enables current's vector state to be
polluted with guest data.  current->thread.sve_state may be
unallocated or not large enough, so this can also trigger a NULL
dereference or buffer overrun.

Instead of this, TIF_SVE should be configured properly for the
guest when calling fpsimd_save() with the vcpu context loaded.

This patch ensures this by delaying restoration of current's
TIF_SVE until after the call to fpsimd_save().

Fixes: e6b673b741ea ("KVM: arm64: Optimise FPSIMD handling to reduce guest/host thrashing")
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
 arch/arm64/kvm/fpsimd.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kvm/fpsimd.c b/arch/arm64/kvm/fpsimd.c
index 98d19d1afa50..aac7808ce216 100644
--- a/arch/arm64/kvm/fpsimd.c
+++ b/arch/arm64/kvm/fpsimd.c
@@ -103,9 +103,6 @@ void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu)
 
 	local_irq_save(flags);
 
-	update_thread_flag(TIF_SVE,
-			   vcpu->arch.flags & KVM_ARM64_HOST_SVE_IN_USE);
-
 	if (vcpu->arch.flags & KVM_ARM64_FP_ENABLED) {
 		/* Clean guest FP state to memory and invalidate cpu view */
 		fpsimd_save();
@@ -124,5 +121,8 @@ void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu)
 			sysreg_clear_set(CPACR_EL1, CPACR_EL1_ZEN_EL0EN, 0);
 	}
 
+	update_thread_flag(TIF_SVE,
+			   vcpu->arch.flags & KVM_ARM64_HOST_SVE_IN_USE);
+
 	local_irq_restore(flags);
 }
-- 
2.17.1

[PATCH 5/8] KVM: arm64: Avoid mistaken attempts to save SVE state for vcpus

[Marc Zyngier]

From: Dave Martin <Dave.Martin@arm.com>

Commit e6b673b ("KVM: arm64: Optimise FPSIMD handling to reduce
guest/host thrashing") uses fpsimd_save() to save the FPSIMD state
for a vcpu when scheduling the vcpu out.  However, currently
current's value of TIF_SVE is restored before calling fpsimd_save()
which means that fpsimd_save() may erroneously attempt to save SVE
state from the vcpu.  This enables current's vector state to be
polluted with guest data.  current->thread.sve_state may be
unallocated or not large enough, so this can also trigger a NULL
dereference or buffer overrun.

Instead of this, TIF_SVE should be configured properly for the
guest when calling fpsimd_save() with the vcpu context loaded.

This patch ensures this by delaying restoration of current's
TIF_SVE until after the call to fpsimd_save().

Fixes: e6b673b741ea ("KVM: arm64: Optimise FPSIMD handling to reduce guest/host thrashing")
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
 arch/arm64/kvm/fpsimd.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kvm/fpsimd.c b/arch/arm64/kvm/fpsimd.c
index 98d19d1afa50..aac7808ce216 100644
--- a/arch/arm64/kvm/fpsimd.c
+++ b/arch/arm64/kvm/fpsimd.c
@@ -103,9 +103,6 @@ void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu)
 
 	local_irq_save(flags);
 
-	update_thread_flag(TIF_SVE,
-			   vcpu->arch.flags & KVM_ARM64_HOST_SVE_IN_USE);
-
 	if (vcpu->arch.flags & KVM_ARM64_FP_ENABLED) {
 		/* Clean guest FP state to memory and invalidate cpu view */
 		fpsimd_save();
@@ -124,5 +121,8 @@ void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu)
 			sysreg_clear_set(CPACR_EL1, CPACR_EL1_ZEN_EL0EN, 0);
 	}
 
+	update_thread_flag(TIF_SVE,
+			   vcpu->arch.flags & KVM_ARM64_HOST_SVE_IN_USE);
+
 	local_irq_restore(flags);
 }
-- 
2.17.1

[PATCH 6/8] KVM: arm/arm64: add WARN_ON if size is not PAGE_SIZE aligned in unmap_stage2_range

[Marc Zyngier]

From: Jia He <hejianet@gmail.com>

There is a panic in armv8a server(QDF2400) under memory pressure tests
(start 20 guests and run memhog in the host).

---------------------------------begin--------------------------------
[35380.800950] BUG: Bad page state in process qemu-kvm  pfn:dd0b6
[35380.805825] page:ffff7fe003742d80 count:-4871 mapcount:-2126053375
mapping:          (null) index:0x0
[35380.815024] flags: 0x1fffc00000000000()
[35380.818845] raw: 1fffc00000000000 0000000000000000 0000000000000000
ffffecf981470000
[35380.826569] raw: dead000000000100 dead000000000200 ffff8017c001c000
0000000000000000
[35380.805825] page:ffff7fe003742d80 count:-4871 mapcount:-2126053375
mapping:          (null) index:0x0
[35380.815024] flags: 0x1fffc00000000000()
[35380.818845] raw: 1fffc00000000000 0000000000000000 0000000000000000
ffffecf981470000
[35380.826569] raw: dead000000000100 dead000000000200 ffff8017c001c000
0000000000000000
[35380.834294] page dumped because: nonzero _refcount
[...]
--------------------------------end--------------------------------------

The root cause might be what was fixed at [1]. But from the KVM points of
view, it would be better if the issue was caught earlier.

If the size is not PAGE_SIZE aligned, unmap_stage2_range might unmap the
wrong(more or less) page range. Hence it caused the "BUG: Bad page
state"

Let's WARN in that case, so that the issue is obvious.

[1] https://lkml.org/lkml/2018/5/3/1042

Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: jia.he@hxt-semitech.com
[maz: tidied up commit message]
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
 virt/kvm/arm/mmu.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
index 8d90de213ce9..1d90d79706bd 100644
--- a/virt/kvm/arm/mmu.c
+++ b/virt/kvm/arm/mmu.c
@@ -297,6 +297,8 @@ static void unmap_stage2_range(struct kvm *kvm, phys_addr_t start, u64 size)
 	phys_addr_t next;
 
 	assert_spin_locked(&kvm->mmu_lock);
+	WARN_ON(size & ~PAGE_MASK);
+
 	pgd = kvm->arch.pgd + stage2_pgd_index(addr);
 	do {
 		/*
-- 
2.17.1

[PATCH 6/8] KVM: arm/arm64: add WARN_ON if size is not PAGE_SIZE aligned in unmap_stage2_range

[Marc Zyngier]

From: Jia He <hejianet@gmail.com>

There is a panic in armv8a server(QDF2400) under memory pressure tests
(start 20 guests and run memhog in the host).

---------------------------------begin--------------------------------
[35380.800950] BUG: Bad page state in process qemu-kvm  pfn:dd0b6
[35380.805825] page:ffff7fe003742d80 count:-4871 mapcount:-2126053375
mapping:          (null) index:0x0
[35380.815024] flags: 0x1fffc00000000000()
[35380.818845] raw: 1fffc00000000000 0000000000000000 0000000000000000
ffffecf981470000
[35380.826569] raw: dead000000000100 dead000000000200 ffff8017c001c000
0000000000000000
[35380.805825] page:ffff7fe003742d80 count:-4871 mapcount:-2126053375
mapping:          (null) index:0x0
[35380.815024] flags: 0x1fffc00000000000()
[35380.818845] raw: 1fffc00000000000 0000000000000000 0000000000000000
ffffecf981470000
[35380.826569] raw: dead000000000100 dead000000000200 ffff8017c001c000
0000000000000000
[35380.834294] page dumped because: nonzero _refcount
[...]
--------------------------------end--------------------------------------

The root cause might be what was fixed at [1]. But from the KVM points of
view, it would be better if the issue was caught earlier.

If the size is not PAGE_SIZE aligned, unmap_stage2_range might unmap the
wrong(more or less) page range. Hence it caused the "BUG: Bad page
state"

Let's WARN in that case, so that the issue is obvious.

[1] https://lkml.org/lkml/2018/5/3/1042

Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: jia.he at hxt-semitech.com
[maz: tidied up commit message]
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
 virt/kvm/arm/mmu.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
index 8d90de213ce9..1d90d79706bd 100644
--- a/virt/kvm/arm/mmu.c
+++ b/virt/kvm/arm/mmu.c
@@ -297,6 +297,8 @@ static void unmap_stage2_range(struct kvm *kvm, phys_addr_t start, u64 size)
 	phys_addr_t next;
 
 	assert_spin_locked(&kvm->mmu_lock);
+	WARN_ON(size & ~PAGE_MASK);
+
 	pgd = kvm->arch.pgd + stage2_pgd_index(addr);
 	do {
 		/*
-- 
2.17.1

[PATCH 7/8] KVM: Enforce error in ioctl for compat tasks when !KVM_COMPAT

[Marc Zyngier]

The current behaviour of the compat ioctls is a bit odd.
We provide a compat_ioctl method when KVM_COMPAT is set, and NULL
otherwise. But NULL means that the normal, non-compat ioctl should
be used directly for compat tasks, and there is no way to actually
prevent a compat task from issueing KVM ioctls.

This patch changes this behaviour, by always registering a compat_ioctl
method, even if KVM_COMPAT is not selected. In that case, the callback
will always return -EINVAL.

Fixes: de8e5d744051568c8aad ("KVM: Disable compat ioctl for s390")
Reported-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
 virt/kvm/kvm_main.c | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index ada21f47f22b..8b47507faab5 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -116,6 +116,11 @@ static long kvm_vcpu_ioctl(struct file *file, unsigned int ioctl,
 #ifdef CONFIG_KVM_COMPAT
 static long kvm_vcpu_compat_ioctl(struct file *file, unsigned int ioctl,
 				  unsigned long arg);
+#define KVM_COMPAT(c)	.compat_ioctl	= (c)
+#else
+static long kvm_no_compat_ioctl(struct file *file, unsigned int ioctl,
+				unsigned long arg) { return -EINVAL; }
+#define KVM_COMPAT(c)	.compat_ioctl	= kvm_no_compat_ioctl
 #endif
 static int hardware_enable_all(void);
 static void hardware_disable_all(void);
@@ -2396,11 +2401,9 @@ static int kvm_vcpu_release(struct inode *inode, struct file *filp)
 static struct file_operations kvm_vcpu_fops = {
 	.release        = kvm_vcpu_release,
 	.unlocked_ioctl = kvm_vcpu_ioctl,
-#ifdef CONFIG_KVM_COMPAT
-	.compat_ioctl   = kvm_vcpu_compat_ioctl,
-#endif
 	.mmap           = kvm_vcpu_mmap,
 	.llseek		= noop_llseek,
+	KVM_COMPAT(kvm_vcpu_compat_ioctl),
 };
 
 /*
@@ -2824,10 +2827,8 @@ static int kvm_device_release(struct inode *inode, struct file *filp)
 
 static const struct file_operations kvm_device_fops = {
 	.unlocked_ioctl = kvm_device_ioctl,
-#ifdef CONFIG_KVM_COMPAT
-	.compat_ioctl = kvm_device_ioctl,
-#endif
 	.release = kvm_device_release,
+	KVM_COMPAT(kvm_device_ioctl),
 };
 
 struct kvm_device *kvm_device_from_filp(struct file *filp)
@@ -3165,10 +3166,8 @@ static long kvm_vm_compat_ioctl(struct file *filp,
 static struct file_operations kvm_vm_fops = {
 	.release        = kvm_vm_release,
 	.unlocked_ioctl = kvm_vm_ioctl,
-#ifdef CONFIG_KVM_COMPAT
-	.compat_ioctl   = kvm_vm_compat_ioctl,
-#endif
 	.llseek		= noop_llseek,
+	KVM_COMPAT(kvm_vm_compat_ioctl),
 };
 
 static int kvm_dev_ioctl_create_vm(unsigned long type)
@@ -3259,8 +3258,8 @@ static long kvm_dev_ioctl(struct file *filp,
 
 static struct file_operations kvm_chardev_ops = {
 	.unlocked_ioctl = kvm_dev_ioctl,
-	.compat_ioctl   = kvm_dev_ioctl,
 	.llseek		= noop_llseek,
+	KVM_COMPAT(kvm_dev_ioctl),
 };
 
 static struct miscdevice kvm_dev = {
-- 
2.17.1

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

[PATCH 7/8] KVM: Enforce error in ioctl for compat tasks when !KVM_COMPAT

[Marc Zyngier]

The current behaviour of the compat ioctls is a bit odd.
We provide a compat_ioctl method when KVM_COMPAT is set, and NULL
otherwise. But NULL means that the normal, non-compat ioctl should
be used directly for compat tasks, and there is no way to actually
prevent a compat task from issueing KVM ioctls.

This patch changes this behaviour, by always registering a compat_ioctl
method, even if KVM_COMPAT is not selected. In that case, the callback
will always return -EINVAL.

Fixes: de8e5d744051568c8aad ("KVM: Disable compat ioctl for s390")
Reported-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Radim Kr?m?? <rkrcmar@redhat.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
 virt/kvm/kvm_main.c | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index ada21f47f22b..8b47507faab5 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -116,6 +116,11 @@ static long kvm_vcpu_ioctl(struct file *file, unsigned int ioctl,
 #ifdef CONFIG_KVM_COMPAT
 static long kvm_vcpu_compat_ioctl(struct file *file, unsigned int ioctl,
 				  unsigned long arg);
+#define KVM_COMPAT(c)	.compat_ioctl	= (c)
+#else
+static long kvm_no_compat_ioctl(struct file *file, unsigned int ioctl,
+				unsigned long arg) { return -EINVAL; }
+#define KVM_COMPAT(c)	.compat_ioctl	= kvm_no_compat_ioctl
 #endif
 static int hardware_enable_all(void);
 static void hardware_disable_all(void);
@@ -2396,11 +2401,9 @@ static int kvm_vcpu_release(struct inode *inode, struct file *filp)
 static struct file_operations kvm_vcpu_fops = {
 	.release        = kvm_vcpu_release,
 	.unlocked_ioctl = kvm_vcpu_ioctl,
-#ifdef CONFIG_KVM_COMPAT
-	.compat_ioctl   = kvm_vcpu_compat_ioctl,
-#endif
 	.mmap           = kvm_vcpu_mmap,
 	.llseek		= noop_llseek,
+	KVM_COMPAT(kvm_vcpu_compat_ioctl),
 };
 
 /*
@@ -2824,10 +2827,8 @@ static int kvm_device_release(struct inode *inode, struct file *filp)
 
 static const struct file_operations kvm_device_fops = {
 	.unlocked_ioctl = kvm_device_ioctl,
-#ifdef CONFIG_KVM_COMPAT
-	.compat_ioctl = kvm_device_ioctl,
-#endif
 	.release = kvm_device_release,
+	KVM_COMPAT(kvm_device_ioctl),
 };
 
 struct kvm_device *kvm_device_from_filp(struct file *filp)
@@ -3165,10 +3166,8 @@ static long kvm_vm_compat_ioctl(struct file *filp,
 static struct file_operations kvm_vm_fops = {
 	.release        = kvm_vm_release,
 	.unlocked_ioctl = kvm_vm_ioctl,
-#ifdef CONFIG_KVM_COMPAT
-	.compat_ioctl   = kvm_vm_compat_ioctl,
-#endif
 	.llseek		= noop_llseek,
+	KVM_COMPAT(kvm_vm_compat_ioctl),
 };
 
 static int kvm_dev_ioctl_create_vm(unsigned long type)
@@ -3259,8 +3258,8 @@ static long kvm_dev_ioctl(struct file *filp,
 
 static struct file_operations kvm_chardev_ops = {
 	.unlocked_ioctl = kvm_dev_ioctl,
-	.compat_ioctl   = kvm_dev_ioctl,
 	.llseek		= noop_llseek,
+	KVM_COMPAT(kvm_dev_ioctl),
 };
 
 static struct miscdevice kvm_dev = {
-- 
2.17.1

[PATCH 8/8] KVM: arm64: Prevent KVM_COMPAT from being selected

[Marc Zyngier]

There is very little point in trying to support the 32bit KVM/arm API
on arm64, and this was never an anticipated use case.

Let's make it clear by not selecting KVM_COMPAT.

Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
 virt/kvm/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig
index 72143cfaf6ec..ea434ddc8499 100644
--- a/virt/kvm/Kconfig
+++ b/virt/kvm/Kconfig
@@ -47,7 +47,7 @@ config KVM_GENERIC_DIRTYLOG_READ_PROTECT
 
 config KVM_COMPAT
        def_bool y
-       depends on KVM && COMPAT && !S390
+       depends on KVM && COMPAT && !(S390 || ARM64)
 
 config HAVE_KVM_IRQ_BYPASS
        bool
-- 
2.17.1

[PATCH 8/8] KVM: arm64: Prevent KVM_COMPAT from being selected

[Marc Zyngier]

There is very little point in trying to support the 32bit KVM/arm API
on arm64, and this was never an anticipated use case.

Let's make it clear by not selecting KVM_COMPAT.

Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
 virt/kvm/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig
index 72143cfaf6ec..ea434ddc8499 100644
--- a/virt/kvm/Kconfig
+++ b/virt/kvm/Kconfig
@@ -47,7 +47,7 @@ config KVM_GENERIC_DIRTYLOG_READ_PROTECT
 
 config KVM_COMPAT
        def_bool y
-       depends on KVM && COMPAT && !S390
+       depends on KVM && COMPAT && !(S390 || ARM64)
 
 config HAVE_KVM_IRQ_BYPASS
        bool
-- 
2.17.1

Re: [GIT PULL] KVM/arm updates for 4.18-rc2

[Radim Krčmář]

2018-06-22 13:49+0100, Marc Zyngier:
> Radim, Paolo,
> 
> This is the first batch of fixes for 4.18, mostly dealing with the
> fallout from Dave's lazy FPSIMD handling. We also have the disabling
> of the compat interface on arm64 (it never had it the first place),
> and a relaxation on the alignment of the GICv3 compatibility
> interface.
> 
> Please pull.

Pulled, thanks.

[GIT PULL] KVM/arm updates for 4.18-rc2

[Radim Krčmář]

2018-06-22 13:49+0100, Marc Zyngier:
> Radim, Paolo,
> 
> This is the first batch of fixes for 4.18, mostly dealing with the
> fallout from Dave's lazy FPSIMD handling. We also have the disabling
> of the compat interface on arm64 (it never had it the first place),
> and a relaxation on the alignment of the GICv3 compatibility
> interface.
> 
> Please pull.

Pulled, thanks.