[PATCH] KVM: Properly check if "page" is valid in kvm_vcpu_unmap

[PATCH] KVM: Properly check if "page" is valid in kvm_vcpu_unmap

[KarimAllah Ahmed]

The field "page" is initialized to KVM_UNMAPPED_PAGE when it is not used
(i.e. when the memory lives outside kernel control). So this check will
always end up using kunmap even for memremap regions.

Fixes: e45adf665a53 ("KVM: Introduce a new guest mapping API")
Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
---
 virt/kvm/kvm_main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 2f2d24a..e629766 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1790,7 +1790,7 @@ void kvm_vcpu_unmap(struct kvm_vcpu *vcpu, struct kvm_host_map *map,
 	if (!map->hva)
 		return;
 
-	if (map->page)
+	if (map->page != KVM_UNMAPPED_PAGE)
 		kunmap(map->page);
 #ifdef CONFIG_HAS_IOMEM
 	else
-- 
2.7.4

Re: [PATCH] KVM: Properly check if "page" is valid in kvm_vcpu_unmap

[Paolo Bonzini]

On 10/07/19 11:13, KarimAllah Ahmed wrote:
> The field "page" is initialized to KVM_UNMAPPED_PAGE when it is not used
> (i.e. when the memory lives outside kernel control). So this check will
> always end up using kunmap even for memremap regions.
> 
> Fixes: e45adf665a53 ("KVM: Introduce a new guest mapping API")
> Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
> ---
>  virt/kvm/kvm_main.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 2f2d24a..e629766 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -1790,7 +1790,7 @@ void kvm_vcpu_unmap(struct kvm_vcpu *vcpu, struct kvm_host_map *map,
>  	if (!map->hva)
>  		return;
>  
> -	if (map->page)
> +	if (map->page != KVM_UNMAPPED_PAGE)
>  		kunmap(map->page);
>  #ifdef CONFIG_HAS_IOMEM
>  	else
> 

Queued, thanks.

Paolo