[v2 PATCH] KVM: nVMX: consult PFEC_MASK and PFEC_MATCH when generating #PF VM-exit

[v2 PATCH] KVM: nVMX: consult PFEC_MASK and PFEC_MATCH when generating #PF VM-exit

[Eugene Korenevsky]

When generating #PF VM-exit, check equality:
(PFEC & PFEC_MASK) == PFEC_MATCH
If there is equality, the 14 bit of exception bitmap is used to take decision
about generating #PF VM-exit. If there is inequality, inverted 14 bit is used.

Signed-off-by: Eugene Korenevsky <ekorenevsky@gmail.com>
---
 arch/x86/kvm/vmx.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 09ccf6c..a8ef8265 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -8206,6 +8206,18 @@ static void nested_ept_uninit_mmu_context(struct kvm_vcpu *vcpu)
 	vcpu->arch.walk_mmu = &vcpu->arch.mmu;
 }
 
+static bool nested_vmx_is_page_fault_vmexit(struct vmcs12 *vmcs12,
+					    u16 error_code)
+{
+	bool inequality, bit;
+
+	bit = (vmcs12->exception_bitmap & (1u << PF_VECTOR)) != 0;
+	inequality =
+		(error_code & vmcs12->page_fault_error_code_mask) !=
+		 vmcs12->page_fault_error_code_match;
+	return inequality ^ bit;
+}
+
 static void vmx_inject_page_fault_nested(struct kvm_vcpu *vcpu,
 		struct x86_exception *fault)
 {
@@ -8213,8 +8225,7 @@ static void vmx_inject_page_fault_nested(struct kvm_vcpu *vcpu,
 
 	WARN_ON(!is_guest_mode(vcpu));
 
-	/* TODO: also check PFEC_MATCH/MASK, not just EB.PF. */
-	if (vmcs12->exception_bitmap & (1u << PF_VECTOR))
+	if (nested_vmx_is_page_fault_vmexit(vmcs12, fault->error_code))
 		nested_vmx_vmexit(vcpu, to_vmx(vcpu)->exit_reason,
 				  vmcs_read32(VM_EXIT_INTR_INFO),
 				  vmcs_readl(EXIT_QUALIFICATION));
-- 
2.0.4

Re: [v2 PATCH] KVM: nVMX: consult PFEC_MASK and PFEC_MATCH when generating #PF VM-exit

[Paolo Bonzini]

On 16/12/2014 20:35, Eugene Korenevsky wrote:
> When generating #PF VM-exit, check equality:
> (PFEC & PFEC_MASK) == PFEC_MATCH
> If there is equality, the 14 bit of exception bitmap is used to take decision
> about generating #PF VM-exit. If there is inequality, inverted 14 bit is used.
> 
> Signed-off-by: Eugene Korenevsky <ekorenevsky@gmail.com>
> ---
>  arch/x86/kvm/vmx.c | 15 +++++++++++++--
>  1 file changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 09ccf6c..a8ef8265 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -8206,6 +8206,18 @@ static void nested_ept_uninit_mmu_context(struct kvm_vcpu *vcpu)
>  	vcpu->arch.walk_mmu = &vcpu->arch.mmu;
>  }
>  
> +static bool nested_vmx_is_page_fault_vmexit(struct vmcs12 *vmcs12,
> +					    u16 error_code)
> +{
> +	bool inequality, bit;
> +
> +	bit = (vmcs12->exception_bitmap & (1u << PF_VECTOR)) != 0;
> +	inequality =
> +		(error_code & vmcs12->page_fault_error_code_mask) !=
> +		 vmcs12->page_fault_error_code_match;
> +	return inequality ^ bit;
> +}
> +
>  static void vmx_inject_page_fault_nested(struct kvm_vcpu *vcpu,
>  		struct x86_exception *fault)
>  {
> @@ -8213,8 +8225,7 @@ static void vmx_inject_page_fault_nested(struct kvm_vcpu *vcpu,
>  
>  	WARN_ON(!is_guest_mode(vcpu));
>  
> -	/* TODO: also check PFEC_MATCH/MASK, not just EB.PF. */
> -	if (vmcs12->exception_bitmap & (1u << PF_VECTOR))
> +	if (nested_vmx_is_page_fault_vmexit(vmcs12, fault->error_code))
>  		nested_vmx_vmexit(vcpu, to_vmx(vcpu)->exit_reason,
>  				  vmcs_read32(VM_EXIT_INTR_INFO),
>  				  vmcs_readl(EXIT_QUALIFICATION));
> 

Applied to kvm/queue, thanks.

Paolo