This needs compat code for !MMU_NOTIFIERS case in kvm-kmod (Jan CC'ed).
Otherwise looks good.
On Wed, Sep 23, 2009 at 09:47:16PM +0300, Izik Eidus wrote:
> When using mmu notifiers, we are allowed to remove the page count
> reference tooken by get_user_pages to a specific page that is mapped
> inside the shadow page tables.
>
> This is needed so we can balance the pagecount against mapcount
> checking.
>
> (Right now kvm increase the pagecount and does not increase the
> mapcount when mapping page into shadow page table entry,
> so when comparing pagecount against mapcount, you have no
> reliable result.)
>
> Signed-off-by: Izik Eidus <ieidus@xxxxxxxxxx>
> ---
> arch/x86/kvm/mmu.c | 7 ++-----
> 1 files changed, 2 insertions(+), 5 deletions(-)
>
> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
> index eca41ae..6c67b23 100644
> --- a/arch/x86/kvm/mmu.c
> +++ b/arch/x86/kvm/mmu.c
> @@ -634,9 +634,7 @@ static void rmap_remove(struct kvm *kvm, u64 *spte)
> if (*spte & shadow_accessed_mask)
> kvm_set_pfn_accessed(pfn);
> if (is_writeble_pte(*spte))
> - kvm_release_pfn_dirty(pfn);
> - else
> - kvm_release_pfn_clean(pfn);
> + kvm_set_pfn_dirty(pfn);
> rmapp = gfn_to_rmap(kvm, sp->gfns[spte - sp->spt], sp->role.level);
> if (!*rmapp) {
> printk(KERN_ERR "rmap_remove: %p %llx 0->BUG\n", spte, *spte);
> @@ -1877,8 +1875,7 @@ static void mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
> page_header_update_slot(vcpu->kvm, sptep, gfn);
> if (!was_rmapped) {
> rmap_count = rmap_add(vcpu, sptep, gfn);
> - if (!is_rmap_spte(*sptep))
> - kvm_release_pfn_clean(pfn);
> + kvm_release_pfn_clean(pfn);
> if (rmap_count > RMAP_RECYCLE_THRESHOLD)
> rmap_recycle(vcpu, sptep, gfn);
> } else {
> --
> 1.5.6.5
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