Re: KVM: MMU: always invalidate and flush on spte page size change

[Avi Kivity <avi@redhat.com>]

On 05/28/2010 03:44 PM, Marcelo Tosatti wrote:
> Always invalidate spte and flush TLBs when changing page size, to make
> sure different sized translations for the same address are never cached
> in a CPU's TLB.
>
> The first case where this occurs is when a non-leaf spte pointer is
> overwritten by a leaf, large spte entry. This can happen after dirty
> logging is disabled on a memslot, for example.
>
> The second case is a leaf, large spte entry is overwritten with a
> non-leaf spte pointer, in __direct_map. Note this cannot happen now
> because the only potential source of such overwrite is dirty logging
> being enabled, which zaps all MMU pages. But this might change
> in the future, so better be robust against it.
>
> Noticed by Andrea.
>
> KVM-Stable-Tag
> Signed-off-by: Marcelo Tosatti<mtosatti@redhat.com>
>
> Index: kvm/arch/x86/kvm/mmu.c
> ===================================================================
> --- kvm.orig/arch/x86/kvm/mmu.c
> +++ kvm/arch/x86/kvm/mmu.c
> @@ -1952,6 +1952,8 @@ static void mmu_set_spte(struct kvm_vcpu
>
>   			child = page_header(pte&  PT64_BASE_ADDR_MASK);
>   			mmu_page_remove_parent_pte(child, sptep);
> +			__set_spte(sptep, shadow_trap_nonpresent_pte);
> +			kvm_flush_remote_tlbs(vcpu->kvm);
>   		} else if (pfn != spte_to_pfn(*sptep)) {
>   			pgprintk("hfn old %lx new %lx\n",
>   				 spte_to_pfn(*sptep), pfn);
>    

Applied this bit.

> @@ -2015,6 +2017,16 @@ static int __direct_map(struct kvm_vcpu
>   			break;
>   		}
>
> +		if (is_shadow_present_pte(*iterator.sptep)&&
> +		    !is_large_pte(*iterator.sptep))
> +			continue;
> +
> +		if (is_large_pte(*iterator.sptep)) {
> +			rmap_remove(vcpu->kvm, iterator.sptep);
> +			__set_spte(iterator.sptep, shadow_trap_nonpresent_pte);
> +			kvm_flush_remote_tlbs(vcpu->kvm);
> +		}
> +
>    

Don't we have exactly the same issue in FNAME(fetch)()?

-- 
error compiling committee.c: too many arguments to function