* KVM: MMU: make kvm_mmu_available_pages robust against n_used_mmu_pages > n_max_mmu_pages
@ 2013-03-13 1:36 Marcelo Tosatti
2013-03-13 5:17 ` Xiao Guangrong
2013-03-13 9:46 ` Gleb Natapov
0 siblings, 2 replies; 3+ messages in thread
From: Marcelo Tosatti @ 2013-03-13 1:36 UTC (permalink / raw)
To: kvm; +Cc: Gleb Natapov, Paolo Bonzini, Ulrich Obergfell
As noticed by Ulrich Obergfell <uobergfe@redhat.com>, the mmu
counters are for beancounting purposes only - so n_used_mmu_pages and
n_max_mmu_pages could be relaxed (example: before f0f5933a1626c8df7b),
resulting in n_used_mmu_pages > n_max_mmu_pages.
Make code robust against n_used_mmu_pages > n_max_mmu_pages.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index 6987108..3b1ad00 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -57,8 +57,11 @@ int kvm_init_shadow_mmu(struct kvm_vcpu *vcpu, struct kvm_mmu *context);
static inline unsigned int kvm_mmu_available_pages(struct kvm *kvm)
{
- return kvm->arch.n_max_mmu_pages -
- kvm->arch.n_used_mmu_pages;
+ if (kvm->arch.n_max_mmu_pages > kvm->arch.n_used_mmu_pages)
+ return kvm->arch.n_max_mmu_pages -
+ kvm->arch.n_used_mmu_pages;
+
+ return 0;
}
static inline void kvm_mmu_free_some_pages(struct kvm_vcpu *vcpu)
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: KVM: MMU: make kvm_mmu_available_pages robust against n_used_mmu_pages > n_max_mmu_pages
2013-03-13 1:36 KVM: MMU: make kvm_mmu_available_pages robust against n_used_mmu_pages > n_max_mmu_pages Marcelo Tosatti
@ 2013-03-13 5:17 ` Xiao Guangrong
2013-03-13 9:46 ` Gleb Natapov
1 sibling, 0 replies; 3+ messages in thread
From: Xiao Guangrong @ 2013-03-13 5:17 UTC (permalink / raw)
To: Marcelo Tosatti; +Cc: kvm, Gleb Natapov, Paolo Bonzini, Ulrich Obergfell
On 03/13/2013 09:36 AM, Marcelo Tosatti wrote:
>
> As noticed by Ulrich Obergfell <uobergfe@redhat.com>, the mmu
> counters are for beancounting purposes only - so n_used_mmu_pages and
> n_max_mmu_pages could be relaxed (example: before f0f5933a1626c8df7b),
> resulting in n_used_mmu_pages > n_max_mmu_pages.
>
Interesting.
> Make code robust against n_used_mmu_pages > n_max_mmu_pages.
Reviewed-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: KVM: MMU: make kvm_mmu_available_pages robust against n_used_mmu_pages > n_max_mmu_pages
2013-03-13 1:36 KVM: MMU: make kvm_mmu_available_pages robust against n_used_mmu_pages > n_max_mmu_pages Marcelo Tosatti
2013-03-13 5:17 ` Xiao Guangrong
@ 2013-03-13 9:46 ` Gleb Natapov
1 sibling, 0 replies; 3+ messages in thread
From: Gleb Natapov @ 2013-03-13 9:46 UTC (permalink / raw)
To: Marcelo Tosatti; +Cc: kvm, Paolo Bonzini, Ulrich Obergfell
On Tue, Mar 12, 2013 at 10:36:43PM -0300, Marcelo Tosatti wrote:
>
> As noticed by Ulrich Obergfell <uobergfe@redhat.com>, the mmu
> counters are for beancounting purposes only - so n_used_mmu_pages and
> n_max_mmu_pages could be relaxed (example: before f0f5933a1626c8df7b),
> resulting in n_used_mmu_pages > n_max_mmu_pages.
>
> Make code robust against n_used_mmu_pages > n_max_mmu_pages.
>
> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
>
Applied, thanks.
> diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
> index 6987108..3b1ad00 100644
> --- a/arch/x86/kvm/mmu.h
> +++ b/arch/x86/kvm/mmu.h
> @@ -57,8 +57,11 @@ int kvm_init_shadow_mmu(struct kvm_vcpu *vcpu, struct kvm_mmu *context);
>
> static inline unsigned int kvm_mmu_available_pages(struct kvm *kvm)
> {
> - return kvm->arch.n_max_mmu_pages -
> - kvm->arch.n_used_mmu_pages;
> + if (kvm->arch.n_max_mmu_pages > kvm->arch.n_used_mmu_pages)
> + return kvm->arch.n_max_mmu_pages -
> + kvm->arch.n_used_mmu_pages;
> +
> + return 0;
> }
>
> static inline void kvm_mmu_free_some_pages(struct kvm_vcpu *vcpu)
--
Gleb.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2013-03-13 1:36 KVM: MMU: make kvm_mmu_available_pages robust against n_used_mmu_pages > n_max_mmu_pages Marcelo Tosatti
2013-03-13 5:17 ` Xiao Guangrong
2013-03-13 9:46 ` Gleb Natapov
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