[v4,03/14] X86/nVMX: Update the PML table without mapping and unmapping the page
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Message ID 1543829467-18025-4-git-send-email-karahmed@amazon.de
State New
Headers show
Series
  • KVM/X86: Introduce a new guest mapping interface
Related show

Commit Message

KarimAllah Ahmed Dec. 3, 2018, 9:30 a.m. UTC
Update the PML table without mapping and unmapping the page. This also
avoids using kvm_vcpu_gpa_to_page(..) which assumes that there is a "struct
page" for guest memory.

Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
---
v1 -> v2:
- Use kvm_write_guest_page instead of kvm_write_guest (pbonzini)
- Do not use pointer arithmetic for pml_address (pbonzini)
---
 arch/x86/kvm/vmx.c | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)

Comments

David Hildenbrand Dec. 3, 2018, 1:10 p.m. UTC | #1
On 03.12.18 10:30, KarimAllah Ahmed wrote:
> Update the PML table without mapping and unmapping the page. This also
> avoids using kvm_vcpu_gpa_to_page(..) which assumes that there is a "struct
> page" for guest memory.
> 
> Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
> ---
> v1 -> v2:
> - Use kvm_write_guest_page instead of kvm_write_guest (pbonzini)
> - Do not use pointer arithmetic for pml_address (pbonzini)
> ---
>  arch/x86/kvm/vmx.c | 14 +++++---------
>  1 file changed, 5 insertions(+), 9 deletions(-)
> 
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 75817cb..6d6dfa9 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -14427,9 +14427,7 @@ static int vmx_write_pml_buffer(struct kvm_vcpu *vcpu)
>  {
>  	struct vmcs12 *vmcs12;
>  	struct vcpu_vmx *vmx = to_vmx(vcpu);
> -	gpa_t gpa;
> -	struct page *page = NULL;
> -	u64 *pml_address;
> +	gpa_t gpa, dst;
>  
>  	if (is_guest_mode(vcpu)) {
>  		WARN_ON_ONCE(vmx->nested.pml_full);
> @@ -14449,15 +14447,13 @@ static int vmx_write_pml_buffer(struct kvm_vcpu *vcpu)
>  		}
>  
>  		gpa = vmcs_read64(GUEST_PHYSICAL_ADDRESS) & ~0xFFFull;
> +		dst = vmcs12->pml_address + sizeof(u64) * vmcs12->guest_pml_index;
>  
> -		page = kvm_vcpu_gpa_to_page(vcpu, vmcs12->pml_address);
> -		if (is_error_page(page))
> +		if (kvm_write_guest_page(vcpu->kvm, gpa_to_gfn(dst), &gpa,
> +					 offset_in_page(dst), sizeof(gpa)))
>  			return 0;
>  
> -		pml_address = kmap(page);
> -		pml_address[vmcs12->guest_pml_index--] = gpa;
> -		kunmap(page);
> -		kvm_release_page_clean(page);

So we've written to the page but released it as clean ... shouldn't that
have been kvm_release_page_dirty?

... also, shouldn't there have been a mark_page_dirty() ?
(to mark it dirty for migration?)

Your patch certainly fixes both conditions (if it was in fact broken).
In that case, we should maybe add that to the cover letter.

Reviewed-by: David Hildenbrand <david@redhat.com>

> +		vmcs12->guest_pml_index--;
>  	}
>  
>  	return 0;
>

Patch
diff mbox series

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 75817cb..6d6dfa9 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -14427,9 +14427,7 @@  static int vmx_write_pml_buffer(struct kvm_vcpu *vcpu)
 {
 	struct vmcs12 *vmcs12;
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
-	gpa_t gpa;
-	struct page *page = NULL;
-	u64 *pml_address;
+	gpa_t gpa, dst;
 
 	if (is_guest_mode(vcpu)) {
 		WARN_ON_ONCE(vmx->nested.pml_full);
@@ -14449,15 +14447,13 @@  static int vmx_write_pml_buffer(struct kvm_vcpu *vcpu)
 		}
 
 		gpa = vmcs_read64(GUEST_PHYSICAL_ADDRESS) & ~0xFFFull;
+		dst = vmcs12->pml_address + sizeof(u64) * vmcs12->guest_pml_index;
 
-		page = kvm_vcpu_gpa_to_page(vcpu, vmcs12->pml_address);
-		if (is_error_page(page))
+		if (kvm_write_guest_page(vcpu->kvm, gpa_to_gfn(dst), &gpa,
+					 offset_in_page(dst), sizeof(gpa)))
 			return 0;
 
-		pml_address = kmap(page);
-		pml_address[vmcs12->guest_pml_index--] = gpa;
-		kunmap(page);
-		kvm_release_page_clean(page);
+		vmcs12->guest_pml_index--;
 	}
 
 	return 0;