Re: [PATCH v5 11/13] KVM/nVMX: Use kvm_vcpu_map for accessing the shadow VMCS

[Konrad Rzeszutek Wilk]

On Wed, Jan 09, 2019 at 10:42:11AM +0100, KarimAllah Ahmed wrote:
> Use kvm_vcpu_map for accessing the shadow VMCS since using
> kvm_vcpu_gpa_to_page() and kmap() will only work for guest memory that has
> a "struct page".
> 
> Signed-off-by: KarimAllah Ahmed 

Reviewed-by: Konrad Rzessutek Wilk 

[PATCH v5 11/13] KVM/nVMX: Use kvm_vcpu_map for accessing the shadow VMCS

[KarimAllah Ahmed]

Use kvm_vcpu_map for accessing the shadow VMCS since using
kvm_vcpu_gpa_to_page() and kmap() will only work for guest memory that has
a "struct page".

Signed-off-by: KarimAllah Ahmed 
---
v4 -> v5:
- unmap with dirty flag
---
 arch/x86/kvm/vmx/nested.c | 25 -
 1 file changed, 12 insertions(+), 13 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index b4230ce..04a8b43 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -588,20 +588,20 @@ static inline bool nested_vmx_prepare_msr_bitmap(struct 
kvm_vcpu *vcpu,
 static void nested_cache_shadow_vmcs12(struct kvm_vcpu *vcpu,
   struct vmcs12 *vmcs12)
 {
+   struct kvm_host_map map;
struct vmcs12 *shadow;
-   struct page *page;
 
if (!nested_cpu_has_shadow_vmcs(vmcs12) ||
vmcs12->vmcs_link_pointer == -1ull)
return;
 
shadow = get_shadow_vmcs12(vcpu);
-   page = kvm_vcpu_gpa_to_page(vcpu, vmcs12->vmcs_link_pointer);
 
-   memcpy(shadow, kmap(page), VMCS12_SIZE);
+   if (kvm_vcpu_map(vcpu, gpa_to_gfn(vmcs12->vmcs_link_pointer), &map))
+   return;
 
-   kunmap(page);
-   kvm_release_page_clean(page);
+   memcpy(shadow, map.hva, VMCS12_SIZE);
+   kvm_vcpu_unmap(&map, false);
 }
 
 static void nested_flush_cached_shadow_vmcs12(struct kvm_vcpu *vcpu,
@@ -2637,9 +2637,9 @@ static int nested_vmx_check_vmentry_prereqs(struct 
kvm_vcpu *vcpu,
 static int nested_vmx_check_vmcs_link_ptr(struct kvm_vcpu *vcpu,
  struct vmcs12 *vmcs12)
 {
-   int r;
-   struct page *page;
+   int r = 0;
struct vmcs12 *shadow;
+   struct kvm_host_map map;
 
if (vmcs12->vmcs_link_pointer == -1ull)
return 0;
@@ -2647,17 +2647,16 @@ static int nested_vmx_check_vmcs_link_ptr(struct 
kvm_vcpu *vcpu,
if (!page_address_valid(vcpu, vmcs12->vmcs_link_pointer))
return -EINVAL;
 
-   page = kvm_vcpu_gpa_to_page(vcpu, vmcs12->vmcs_link_pointer);
-   if (is_error_page(page))
+   if (kvm_vcpu_map(vcpu, gpa_to_gfn(vmcs12->vmcs_link_pointer), &map))
return -EINVAL;
 
-   r = 0;
-   shadow = kmap(page);
+   shadow = map.hva;
+
if (shadow->hdr.revision_id != VMCS12_REVISION ||
shadow->hdr.shadow_vmcs != nested_cpu_has_shadow_vmcs(vmcs12))
r = -EINVAL;
-   kunmap(page);
-   kvm_release_page_clean(page);
+
+   kvm_vcpu_unmap(&map, false);
return r;
 }
 
-- 
2.7.4