Re: [PATCH v2 1/5] KVM: MMU: release noslot pfn on the fail pathproperly

From: Marcelo Tosatti
Date: Sat Sep 15 2012 - 11:41:18 EST


On Fri, Sep 14, 2012 at 05:57:22PM +0800, Xiao Guangrong wrote:
> We can not directly call kvm_release_pfn_clean to release the pfn
> since we can meet noslot pfn which is used to cache mmio info into
> spte
>
> Signed-off-by: Xiao Guangrong <xiaoguangrong@xxxxxxxxxxxxxxxxxx>
> ---
> arch/x86/kvm/mmu.c | 6 ++++--
> arch/x86/kvm/paging_tmpl.h | 6 ++++--
> 2 files changed, 8 insertions(+), 4 deletions(-)

Its clearer to the reader if is_invalid_pfn() is used instead of
is_error_pfn.

BTW how about killing this unused helper

static bool mmu_invalid_pfn(pfn_t pfn)
{
return unlikely(is_invalid_pfn(pfn));
}

This can be done inlined.

> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
> index aa0b469..f74c63a 100644
> --- a/arch/x86/kvm/mmu.c
> +++ b/arch/x86/kvm/mmu.c
> @@ -2877,7 +2877,8 @@ static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, u32 error_code,
>
> out_unlock:
> spin_unlock(&vcpu->kvm->mmu_lock);
> - kvm_release_pfn_clean(pfn);
> + if (!is_error_pfn(pfn))
> + kvm_release_pfn_clean(pfn);
> return 0;
> }

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