* [PATCH MANUALSEL 5.4 1/2] KVM: nVMX: eVMCS: Filter out VM_EXIT_SAVE_VMX_PREEMPTION_TIMER
@ 2022-02-09 18:57 Sasha Levin
2022-02-09 18:57 ` [PATCH MANUALSEL 5.4 2/2] KVM: nVMX: WARN on any attempt to allocate shadow VMCS for vmcs02 Sasha Levin
2022-02-10 16:35 ` [PATCH MANUALSEL 5.4 1/2] KVM: nVMX: eVMCS: Filter out VM_EXIT_SAVE_VMX_PREEMPTION_TIMER Paolo Bonzini
0 siblings, 2 replies; 4+ messages in thread
From: Sasha Levin @ 2022-02-09 18:57 UTC (permalink / raw)
To: linux-kernel, stable
Cc: Vitaly Kuznetsov, Paolo Bonzini, Sasha Levin, tglx, mingo, bp,
dave.hansen, x86, kvm
From: Vitaly Kuznetsov <vkuznets@redhat.com>
[ Upstream commit 7a601e2cf61558dfd534a9ecaad09f5853ad8204 ]
Enlightened VMCS v1 doesn't have VMX_PREEMPTION_TIMER_VALUE field,
PIN_BASED_VMX_PREEMPTION_TIMER is also filtered out already so it makes
sense to filter out VM_EXIT_SAVE_VMX_PREEMPTION_TIMER too.
Note, none of the currently existing Windows/Hyper-V versions are known
to enable 'save VMX-preemption timer value' when eVMCS is in use, the
change is aimed at making the filtering future proof.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20220112170134.1904308-3-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/x86/kvm/vmx/evmcs.h | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/vmx/evmcs.h b/arch/x86/kvm/vmx/evmcs.h
index 07ebf6882a458..632bed227152e 100644
--- a/arch/x86/kvm/vmx/evmcs.h
+++ b/arch/x86/kvm/vmx/evmcs.h
@@ -58,7 +58,9 @@ DECLARE_STATIC_KEY_FALSE(enable_evmcs);
SECONDARY_EXEC_SHADOW_VMCS | \
SECONDARY_EXEC_TSC_SCALING | \
SECONDARY_EXEC_PAUSE_LOOP_EXITING)
-#define EVMCS1_UNSUPPORTED_VMEXIT_CTRL (VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL)
+#define EVMCS1_UNSUPPORTED_VMEXIT_CTRL \
+ (VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL | \
+ VM_EXIT_SAVE_VMX_PREEMPTION_TIMER)
#define EVMCS1_UNSUPPORTED_VMENTRY_CTRL (VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL)
#define EVMCS1_UNSUPPORTED_VMFUNC (VMX_VMFUNC_EPTP_SWITCHING)
--
2.34.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH MANUALSEL 5.4 2/2] KVM: nVMX: WARN on any attempt to allocate shadow VMCS for vmcs02
2022-02-09 18:57 [PATCH MANUALSEL 5.4 1/2] KVM: nVMX: eVMCS: Filter out VM_EXIT_SAVE_VMX_PREEMPTION_TIMER Sasha Levin
@ 2022-02-09 18:57 ` Sasha Levin
2022-02-10 16:35 ` Paolo Bonzini
2022-02-10 16:35 ` [PATCH MANUALSEL 5.4 1/2] KVM: nVMX: eVMCS: Filter out VM_EXIT_SAVE_VMX_PREEMPTION_TIMER Paolo Bonzini
1 sibling, 1 reply; 4+ messages in thread
From: Sasha Levin @ 2022-02-09 18:57 UTC (permalink / raw)
To: linux-kernel, stable
Cc: Sean Christopherson, Paolo Bonzini, Sasha Levin, tglx, mingo, bp,
dave.hansen, x86, kvm
From: Sean Christopherson <seanjc@google.com>
[ Upstream commit d6e656cd266cdcc95abd372c7faef05bee271d1a ]
WARN if KVM attempts to allocate a shadow VMCS for vmcs02. KVM emulates
VMCS shadowing but doesn't virtualize it, i.e. KVM should never allocate
a "real" shadow VMCS for L2.
The previous code WARNed but continued anyway with the allocation,
presumably in an attempt to avoid NULL pointer dereference.
However, alloc_vmcs (and hence alloc_shadow_vmcs) can fail, and
indeed the sole caller does:
if (enable_shadow_vmcs && !alloc_shadow_vmcs(vcpu))
goto out_shadow_vmcs;
which makes it not a useful attempt.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220125220527.2093146-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/x86/kvm/vmx/nested.c | 22 ++++++++++++----------
1 file changed, 12 insertions(+), 10 deletions(-)
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 3041015b05f71..44e11f6db3efe 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -4360,18 +4360,20 @@ static struct vmcs *alloc_shadow_vmcs(struct kvm_vcpu *vcpu)
struct loaded_vmcs *loaded_vmcs = vmx->loaded_vmcs;
/*
- * We should allocate a shadow vmcs for vmcs01 only when L1
- * executes VMXON and free it when L1 executes VMXOFF.
- * As it is invalid to execute VMXON twice, we shouldn't reach
- * here when vmcs01 already have an allocated shadow vmcs.
+ * KVM allocates a shadow VMCS only when L1 executes VMXON and frees it
+ * when L1 executes VMXOFF or the vCPU is forced out of nested
+ * operation. VMXON faults if the CPU is already post-VMXON, so it
+ * should be impossible to already have an allocated shadow VMCS. KVM
+ * doesn't support virtualization of VMCS shadowing, so vmcs01 should
+ * always be the loaded VMCS.
*/
- WARN_ON(loaded_vmcs == &vmx->vmcs01 && loaded_vmcs->shadow_vmcs);
+ if (WARN_ON(loaded_vmcs != &vmx->vmcs01 || loaded_vmcs->shadow_vmcs))
+ return loaded_vmcs->shadow_vmcs;
+
+ loaded_vmcs->shadow_vmcs = alloc_vmcs(true);
+ if (loaded_vmcs->shadow_vmcs)
+ vmcs_clear(loaded_vmcs->shadow_vmcs);
- if (!loaded_vmcs->shadow_vmcs) {
- loaded_vmcs->shadow_vmcs = alloc_vmcs(true);
- if (loaded_vmcs->shadow_vmcs)
- vmcs_clear(loaded_vmcs->shadow_vmcs);
- }
return loaded_vmcs->shadow_vmcs;
}
--
2.34.1
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH MANUALSEL 5.4 2/2] KVM: nVMX: WARN on any attempt to allocate shadow VMCS for vmcs02
2022-02-09 18:57 ` [PATCH MANUALSEL 5.4 2/2] KVM: nVMX: WARN on any attempt to allocate shadow VMCS for vmcs02 Sasha Levin
@ 2022-02-10 16:35 ` Paolo Bonzini
0 siblings, 0 replies; 4+ messages in thread
From: Paolo Bonzini @ 2022-02-10 16:35 UTC (permalink / raw)
To: Sasha Levin, linux-kernel, stable
Cc: Sean Christopherson, tglx, mingo, bp, dave.hansen, x86, kvm
On 2/9/22 19:57, Sasha Levin wrote:
> From: Sean Christopherson <seanjc@google.com>
>
> [ Upstream commit d6e656cd266cdcc95abd372c7faef05bee271d1a ]
>
> WARN if KVM attempts to allocate a shadow VMCS for vmcs02. KVM emulates
> VMCS shadowing but doesn't virtualize it, i.e. KVM should never allocate
> a "real" shadow VMCS for L2.
>
> The previous code WARNed but continued anyway with the allocation,
> presumably in an attempt to avoid NULL pointer dereference.
> However, alloc_vmcs (and hence alloc_shadow_vmcs) can fail, and
> indeed the sole caller does:
>
> if (enable_shadow_vmcs && !alloc_shadow_vmcs(vcpu))
> goto out_shadow_vmcs;
>
> which makes it not a useful attempt.
>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> Message-Id: <20220125220527.2093146-1-seanjc@google.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> Signed-off-by: Sasha Levin <sashal@kernel.org>
> ---
> arch/x86/kvm/vmx/nested.c | 22 ++++++++++++----------
> 1 file changed, 12 insertions(+), 10 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> index 3041015b05f71..44e11f6db3efe 100644
> --- a/arch/x86/kvm/vmx/nested.c
> +++ b/arch/x86/kvm/vmx/nested.c
> @@ -4360,18 +4360,20 @@ static struct vmcs *alloc_shadow_vmcs(struct kvm_vcpu *vcpu)
> struct loaded_vmcs *loaded_vmcs = vmx->loaded_vmcs;
>
> /*
> - * We should allocate a shadow vmcs for vmcs01 only when L1
> - * executes VMXON and free it when L1 executes VMXOFF.
> - * As it is invalid to execute VMXON twice, we shouldn't reach
> - * here when vmcs01 already have an allocated shadow vmcs.
> + * KVM allocates a shadow VMCS only when L1 executes VMXON and frees it
> + * when L1 executes VMXOFF or the vCPU is forced out of nested
> + * operation. VMXON faults if the CPU is already post-VMXON, so it
> + * should be impossible to already have an allocated shadow VMCS. KVM
> + * doesn't support virtualization of VMCS shadowing, so vmcs01 should
> + * always be the loaded VMCS.
> */
> - WARN_ON(loaded_vmcs == &vmx->vmcs01 && loaded_vmcs->shadow_vmcs);
> + if (WARN_ON(loaded_vmcs != &vmx->vmcs01 || loaded_vmcs->shadow_vmcs))
> + return loaded_vmcs->shadow_vmcs;
> +
> + loaded_vmcs->shadow_vmcs = alloc_vmcs(true);
> + if (loaded_vmcs->shadow_vmcs)
> + vmcs_clear(loaded_vmcs->shadow_vmcs);
>
> - if (!loaded_vmcs->shadow_vmcs) {
> - loaded_vmcs->shadow_vmcs = alloc_vmcs(true);
> - if (loaded_vmcs->shadow_vmcs)
> - vmcs_clear(loaded_vmcs->shadow_vmcs);
> - }
> return loaded_vmcs->shadow_vmcs;
> }
>
NACK
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH MANUALSEL 5.4 1/2] KVM: nVMX: eVMCS: Filter out VM_EXIT_SAVE_VMX_PREEMPTION_TIMER
2022-02-09 18:57 [PATCH MANUALSEL 5.4 1/2] KVM: nVMX: eVMCS: Filter out VM_EXIT_SAVE_VMX_PREEMPTION_TIMER Sasha Levin
2022-02-09 18:57 ` [PATCH MANUALSEL 5.4 2/2] KVM: nVMX: WARN on any attempt to allocate shadow VMCS for vmcs02 Sasha Levin
@ 2022-02-10 16:35 ` Paolo Bonzini
1 sibling, 0 replies; 4+ messages in thread
From: Paolo Bonzini @ 2022-02-10 16:35 UTC (permalink / raw)
To: Sasha Levin, linux-kernel, stable
Cc: Vitaly Kuznetsov, tglx, mingo, bp, dave.hansen, x86, kvm
On 2/9/22 19:57, Sasha Levin wrote:
> From: Vitaly Kuznetsov <vkuznets@redhat.com>
>
> [ Upstream commit 7a601e2cf61558dfd534a9ecaad09f5853ad8204 ]
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Paolo
> Enlightened VMCS v1 doesn't have VMX_PREEMPTION_TIMER_VALUE field,
> PIN_BASED_VMX_PREEMPTION_TIMER is also filtered out already so it makes
> sense to filter out VM_EXIT_SAVE_VMX_PREEMPTION_TIMER too.
>
> Note, none of the currently existing Windows/Hyper-V versions are known
> to enable 'save VMX-preemption timer value' when eVMCS is in use, the
> change is aimed at making the filtering future proof.
>
> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> Message-Id: <20220112170134.1904308-3-vkuznets@redhat.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> Signed-off-by: Sasha Levin <sashal@kernel.org>
> ---
> arch/x86/kvm/vmx/evmcs.h | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/vmx/evmcs.h b/arch/x86/kvm/vmx/evmcs.h
> index 07ebf6882a458..632bed227152e 100644
> --- a/arch/x86/kvm/vmx/evmcs.h
> +++ b/arch/x86/kvm/vmx/evmcs.h
> @@ -58,7 +58,9 @@ DECLARE_STATIC_KEY_FALSE(enable_evmcs);
> SECONDARY_EXEC_SHADOW_VMCS | \
> SECONDARY_EXEC_TSC_SCALING | \
> SECONDARY_EXEC_PAUSE_LOOP_EXITING)
> -#define EVMCS1_UNSUPPORTED_VMEXIT_CTRL (VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL)
> +#define EVMCS1_UNSUPPORTED_VMEXIT_CTRL \
> + (VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL | \
> + VM_EXIT_SAVE_VMX_PREEMPTION_TIMER)
> #define EVMCS1_UNSUPPORTED_VMENTRY_CTRL (VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL)
> #define EVMCS1_UNSUPPORTED_VMFUNC (VMX_VMFUNC_EPTP_SWITCHING)
>
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2022-02-10 16:36 UTC | newest]
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2022-02-09 18:57 [PATCH MANUALSEL 5.4 1/2] KVM: nVMX: eVMCS: Filter out VM_EXIT_SAVE_VMX_PREEMPTION_TIMER Sasha Levin
2022-02-09 18:57 ` [PATCH MANUALSEL 5.4 2/2] KVM: nVMX: WARN on any attempt to allocate shadow VMCS for vmcs02 Sasha Levin
2022-02-10 16:35 ` Paolo Bonzini
2022-02-10 16:35 ` [PATCH MANUALSEL 5.4 1/2] KVM: nVMX: eVMCS: Filter out VM_EXIT_SAVE_VMX_PREEMPTION_TIMER Paolo Bonzini
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