[PATCH v2] KVM: arm64: Populate fault info for watchpoint

When handling ESR_ELx_EC_WATCHPT_LOW, far_el2 member of struct
kvm_vcpu_fault_info will be copied to far member of struct
kvm_debug_exit_arch and exposed to the userspace. The userspace will
see stale values from older faults if the fault info does not get
populated.

Fixes: 8fb2046180a0 ("KVM: arm64: Move early handlers to per-EC handlers")
Suggested-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Akihiko Odaki <redacted>
---
 arch/arm64/kvm/hyp/include/hyp/switch.h | 8 ++++++--
 arch/arm64/kvm/hyp/nvhe/switch.c        | 2 ++
 arch/arm64/kvm/hyp/vhe/switch.c         | 1 +
 3 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h
index 07d37ff88a3f..33f4d4200329 100644
--- a/arch/arm64/kvm/hyp/include/hyp/switch.h
+++ b/arch/arm64/kvm/hyp/include/hyp/switch.h

@@ -351,17 +351,21 @@ static bool kvm_hyp_handle_cp15_32(struct kvm_vcpu *vcpu, u64 *exit_code)
 	return false;
 }
 
-static bool kvm_hyp_handle_iabt_low(struct kvm_vcpu *vcpu, u64 *exit_code)
+static bool kvm_hyp_handle_memory_fault(struct kvm_vcpu *vcpu, u64 *exit_code)
 {
 	if (!__populate_fault_info(vcpu))
 		return true;
 
 	return false;
 }
+static bool kvm_hyp_handle_iabt_low(struct kvm_vcpu *vcpu, u64 *exit_code)
+	__alias(kvm_hyp_handle_memory_fault);
+static bool kvm_hyp_handle_watchpt_low(struct kvm_vcpu *vcpu, u64 *exit_code)
+	__alias(kvm_hyp_handle_memory_fault);
 
 static bool kvm_hyp_handle_dabt_low(struct kvm_vcpu *vcpu, u64 *exit_code)
 {
-	if (!__populate_fault_info(vcpu))
+	if (kvm_hyp_handle_memory_fault(vcpu, exit_code))
 		return true;
 
 	if (static_branch_unlikely(&vgic_v2_cpuif_trap)) {

diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c
index c2cb46ca4fb6..895fb3200076 100644
--- a/arch/arm64/kvm/hyp/nvhe/switch.c
+++ b/arch/arm64/kvm/hyp/nvhe/switch.c

@@ -186,6 +186,7 @@ static const exit_handler_fn hyp_exit_handlers[] = {
 	[ESR_ELx_EC_FP_ASIMD]		= kvm_hyp_handle_fpsimd,
 	[ESR_ELx_EC_IABT_LOW]		= kvm_hyp_handle_iabt_low,
 	[ESR_ELx_EC_DABT_LOW]		= kvm_hyp_handle_dabt_low,
+	[ESR_ELx_EC_WATCHPT_LOW]	= kvm_hyp_handle_watchpt_low,
 	[ESR_ELx_EC_PAC]		= kvm_hyp_handle_ptrauth,
 };
 

@@ -196,6 +197,7 @@ static const exit_handler_fn pvm_exit_handlers[] = {
 	[ESR_ELx_EC_FP_ASIMD]		= kvm_hyp_handle_fpsimd,
 	[ESR_ELx_EC_IABT_LOW]		= kvm_hyp_handle_iabt_low,
 	[ESR_ELx_EC_DABT_LOW]		= kvm_hyp_handle_dabt_low,
+	[ESR_ELx_EC_WATCHPT_LOW]	= kvm_hyp_handle_watchpt_low,
 	[ESR_ELx_EC_PAC]		= kvm_hyp_handle_ptrauth,
 };
 

diff --git a/arch/arm64/kvm/hyp/vhe/switch.c b/arch/arm64/kvm/hyp/vhe/switch.c
index 1a97391fedd2..45ac4a59cc2c 100644
--- a/arch/arm64/kvm/hyp/vhe/switch.c
+++ b/arch/arm64/kvm/hyp/vhe/switch.c

@@ -110,6 +110,7 @@ static const exit_handler_fn hyp_exit_handlers[] = {
 	[ESR_ELx_EC_FP_ASIMD]		= kvm_hyp_handle_fpsimd,
 	[ESR_ELx_EC_IABT_LOW]		= kvm_hyp_handle_iabt_low,
 	[ESR_ELx_EC_DABT_LOW]		= kvm_hyp_handle_dabt_low,
+	[ESR_ELx_EC_WATCHPT_LOW]	= kvm_hyp_handle_watchpt_low,
 	[ESR_ELx_EC_PAC]		= kvm_hyp_handle_ptrauth,
 };
 

-- 
2.40.1


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On Tue, 30 May 2023 03:46:51 +0100,
Akihiko Odaki [off-list ref] wrote:

When handling ESR_ELx_EC_WATCHPT_LOW, far_el2 member of struct
kvm_vcpu_fault_info will be copied to far member of struct
kvm_debug_exit_arch and exposed to the userspace. The userspace will
see stale values from older faults if the fault info does not get
populated.

Fixes: 8fb2046180a0 ("KVM: arm64: Move early handlers to per-EC handlers")
Suggested-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Akihiko Odaki <redacted>

Thanks for respining this quickly. I've added a Cc: stable as we need
to get this backported.

Cheers,

	M.

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

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On Tue, 30 May 2023 11:46:51 +0900, Akihiko Odaki wrote:

When handling ESR_ELx_EC_WATCHPT_LOW, far_el2 member of struct
kvm_vcpu_fault_info will be copied to far member of struct
kvm_debug_exit_arch and exposed to the userspace. The userspace will
see stale values from older faults if the fault info does not get
populated.

Applied to fixes, thanks!

[1/1] KVM: arm64: Populate fault info for watchpoint
      commit: 811154e234db72f0a11557a84ba9640f8b3bc823

Cheers,

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



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