Re: [RFC PATCH v6 26/92] kvm: x86: add kvm_mmu_nested_pagefault()

[Paolo Bonzini]

On 09/08/19 17:59, Adalbert Lazăr wrote:
> +static bool vmx_nested_pagefault(struct kvm_vcpu *vcpu)
> +{
> + if (vcpu->arch.exit_qualification & EPT_VIOLATION_GVA_TRANSLATED)
> + return false;
> + return true;
> +}
> +

This hook is misnamed; it has nothing to do with nested virtualization.
 Rather, it returns true if it the failure happened while translating
the address of a guest page table.

SVM makes the same information available in EXITINFO[33].

Paolo
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[RFC PATCH v6 26/92] kvm: x86: add kvm_mmu_nested_pagefault()

[Adalbert Lazăr]

From: Mihai Donțu 

This is needed to filter #PF introspection events.

Signed-off-by: Mihai Donțu 
Co-developed-by: Nicușor Cîțu 
Signed-off-by: Nicușor Cîțu 
Signed-off-by: Adalbert Lazăr 
---
 arch/x86/include/asm/kvm_host.h | 4 
 arch/x86/kvm/mmu.c  | 5 +
 arch/x86/kvm/svm.c  | 7 +++
 arch/x86/kvm/vmx/vmx.c  | 9 +
 4 files changed, 25 insertions(+)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 2d6bde6fa59f..7da1137a2b82 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1004,6 +1004,8 @@ struct kvm_x86_ops {
bool (*has_emulated_msr)(int index);
void (*cpuid_update)(struct kvm_vcpu *vcpu);
 
+   bool (*nested_pagefault)(struct kvm_vcpu *vcpu);
+
struct kvm *(*vm_alloc)(void);
void (*vm_free)(struct kvm *);
int (*vm_init)(struct kvm *kvm);
@@ -1593,4 +1595,6 @@ static inline int kvm_cpu_get_apicid(int mps_cpu)
 #define put_smstate(type, buf, offset, val)  \
*(type *)((buf) + (offset) - 0x7e00) = val
 
+bool kvm_mmu_nested_pagefault(struct kvm_vcpu *vcpu);
+
 #endif /* _ASM_X86_KVM_HOST_H */
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index ff053f17b8c2..9eaf6cc776a9 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -6169,3 +6169,8 @@ void kvm_mmu_module_exit(void)
unregister_shrinker(_shrinker);
mmu_audit_disable();
 }
+
+bool kvm_mmu_nested_pagefault(struct kvm_vcpu *vcpu)
+{
+   return kvm_x86_ops->nested_pagefault(vcpu);
+}
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index f13a3a24d360..3c099c56099c 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -7098,6 +7098,11 @@ static int nested_enable_evmcs(struct kvm_vcpu *vcpu,
return -ENODEV;
 }
 
+static bool svm_nested_pagefault(struct kvm_vcpu *vcpu)
+{
+   return false;
+}
+
 static struct kvm_x86_ops svm_x86_ops __ro_after_init = {
.cpu_has_kvm_support = has_svm,
.disabled_by_bios = is_disabled,
@@ -7109,6 +7114,8 @@ static struct kvm_x86_ops svm_x86_ops __ro_after_init = {
.cpu_has_accelerated_tpr = svm_cpu_has_accelerated_tpr,
.has_emulated_msr = svm_has_emulated_msr,
 
+   .nested_pagefault = svm_nested_pagefault,
+
.vcpu_create = svm_create_vcpu,
.vcpu_free = svm_free_vcpu,
.vcpu_reset = svm_vcpu_reset,
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 30a6bcd735ec..e10ee8fd1c67 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7682,6 +7682,13 @@ static __exit void hardware_unsetup(void)
free_kvm_area();
 }
 
+static bool vmx_nested_pagefault(struct kvm_vcpu *vcpu)
+{
+   if (vcpu->arch.exit_qualification & EPT_VIOLATION_GVA_TRANSLATED)
+   return false;
+   return true;
+}
+
 static struct kvm_x86_ops vmx_x86_ops __ro_after_init = {
.cpu_has_kvm_support = cpu_has_kvm_support,
.disabled_by_bios = vmx_disabled_by_bios,
@@ -7693,6 +7700,8 @@ static struct kvm_x86_ops vmx_x86_ops __ro_after_init = {
.cpu_has_accelerated_tpr = report_flexpriority,
.has_emulated_msr = vmx_has_emulated_msr,
 
+   .nested_pagefault = vmx_nested_pagefault,
+
.vm_init = vmx_vm_init,
.vm_alloc = vmx_vm_alloc,
.vm_free = vmx_vm_free,
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