diff mbox series

[v3,02/13] X86/nVMX: handle_vmptrld: Copy the VMCS12 directly from guest memory

Message ID 1540074145-31285-3-git-send-email-karahmed@amazon.de
State New, archived
Headers show
Series KVM/X86: Introduce a new guest mapping interface | expand

Commit Message

KarimAllah Ahmed Oct. 20, 2018, 10:22 p.m. UTC
Copy the VMCS12 directly from guest memory instead of the map->copy->unmap
sequence. This also avoids using kvm_vcpu_gpa_to_page() and kmap() which
assumes that there is a "struct page" for guest memory.

Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
---
v1 -> v2:
- Massage commit message a bit.
---
 arch/x86/kvm/vmx.c | 23 +++++++++--------------
 1 file changed, 9 insertions(+), 14 deletions(-)

Comments

Jim Mattson Oct. 22, 2018, 9:32 p.m. UTC | #1
On Sat, Oct 20, 2018 at 3:22 PM, KarimAllah Ahmed <karahmed@amazon.de> wrote:
> Copy the VMCS12 directly from guest memory instead of the map->copy->unmap
> sequence. This also avoids using kvm_vcpu_gpa_to_page() and kmap() which
> assumes that there is a "struct page" for guest memory.
>
> Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
> ---
> v1 -> v2:
> - Massage commit message a bit.
> ---
>  arch/x86/kvm/vmx.c | 23 +++++++++--------------
>  1 file changed, 9 insertions(+), 14 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 358759a..bc45347 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -8879,33 +8879,28 @@ static int handle_vmptrld(struct kvm_vcpu *vcpu)
>         }
>
>         if (vmx->nested.current_vmptr != vmptr) {
> -               struct vmcs12 *new_vmcs12;
> -               struct page *page;
> -               page = kvm_vcpu_gpa_to_page(vcpu, vmptr);
> -               if (is_error_page(page)) {
> +               struct vmcs12 *new_vmcs12 = (struct vmcs12 *)__get_free_page(GFP_KERNEL);
> +
> +               if (!new_vmcs12 ||
> +                   kvm_read_guest(vcpu->kvm, vmptr, new_vmcs12,
> +                                  sizeof(*new_vmcs12))) {
> +                       free_page((unsigned long)new_vmcs12);
>                         nested_vmx_failInvalid(vcpu);

I believe that this failure, like the one below, should be:

nested_vmx_failValid(vcpu, VMXERR_VMPTRLD_INCORRECT_VMCS_REVISION_ID);

First, if there is a valid current VMCS, then nested_vmx_failInvalid
is incorrect. Second, if there is no backing memory, then by PCI bus
error semantics, we should read all 1's, which isn't the correct VMCS
revision ID.

>                         return kvm_skip_emulated_instruction(vcpu);
>                 }
> -               new_vmcs12 = kmap(page);
> +
>                 if (new_vmcs12->hdr.revision_id != VMCS12_REVISION ||
>                     (new_vmcs12->hdr.shadow_vmcs &&
>                      !nested_cpu_has_vmx_shadow_vmcs(vcpu))) {
> -                       kunmap(page);
> -                       kvm_release_page_clean(page);
> +                       free_page((unsigned long)new_vmcs12);
>                         nested_vmx_failValid(vcpu,
>                                 VMXERR_VMPTRLD_INCORRECT_VMCS_REVISION_ID);
>                         return kvm_skip_emulated_instruction(vcpu);
>                 }
>
>                 nested_release_vmcs12(vmx);
> -               /*
> -                * Load VMCS12 from guest memory since it is not already
> -                * cached.
> -                */
>                 memcpy(vmx->nested.cached_vmcs12, new_vmcs12, VMCS12_SIZE);
> -               kunmap(page);
> -               kvm_release_page_clean(page);
> -
> +               free_page((unsigned long)new_vmcs12);
>                 set_current_vmptr(vmx, vmptr);
>         }
>
> --
> 2.7.4
>
diff mbox series

Patch

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 358759a..bc45347 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -8879,33 +8879,28 @@  static int handle_vmptrld(struct kvm_vcpu *vcpu)
 	}
 
 	if (vmx->nested.current_vmptr != vmptr) {
-		struct vmcs12 *new_vmcs12;
-		struct page *page;
-		page = kvm_vcpu_gpa_to_page(vcpu, vmptr);
-		if (is_error_page(page)) {
+		struct vmcs12 *new_vmcs12 = (struct vmcs12 *)__get_free_page(GFP_KERNEL);
+
+		if (!new_vmcs12 ||
+		    kvm_read_guest(vcpu->kvm, vmptr, new_vmcs12,
+				   sizeof(*new_vmcs12))) {
+			free_page((unsigned long)new_vmcs12);
 			nested_vmx_failInvalid(vcpu);
 			return kvm_skip_emulated_instruction(vcpu);
 		}
-		new_vmcs12 = kmap(page);
+
 		if (new_vmcs12->hdr.revision_id != VMCS12_REVISION ||
 		    (new_vmcs12->hdr.shadow_vmcs &&
 		     !nested_cpu_has_vmx_shadow_vmcs(vcpu))) {
-			kunmap(page);
-			kvm_release_page_clean(page);
+			free_page((unsigned long)new_vmcs12);
 			nested_vmx_failValid(vcpu,
 				VMXERR_VMPTRLD_INCORRECT_VMCS_REVISION_ID);
 			return kvm_skip_emulated_instruction(vcpu);
 		}
 
 		nested_release_vmcs12(vmx);
-		/*
-		 * Load VMCS12 from guest memory since it is not already
-		 * cached.
-		 */
 		memcpy(vmx->nested.cached_vmcs12, new_vmcs12, VMCS12_SIZE);
-		kunmap(page);
-		kvm_release_page_clean(page);
-
+		free_page((unsigned long)new_vmcs12);
 		set_current_vmptr(vmx, vmptr);
 	}