2023-05-30 02:55:12

by Akihiko Odaki

Subject: [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 <[email protected]>
Signed-off-by: Akihiko Odaki <[email protected]>
---
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

2023-05-30 07:51:54

by Marc Zyngier

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

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.

2023-05-30 08:02:14

by Marc Zyngier

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

On Tue, 30 May 2023 03:46:51 +0100,
Akihiko Odaki <[email protected]> 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 <[email protected]>
> Signed-off-by: Akihiko Odaki <[email protected]>

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.