Messages in this thread Patch in this message | | | From | Izik Eidus <> | Subject | [PATCH 1/3] kvm: dont hold pagecount reference for mapped sptes pages. | Date | Tue, 31 Mar 2009 03:00:02 +0300 |
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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@redhat.com> --- 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 b625ed4..df8fbaf 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -567,9 +567,7 @@ 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], is_large_pte(*spte)); if (!*rmapp) { printk(KERN_ERR "rmap_remove: %p %llx 0->BUG\n", spte, *spte); @@ -1812,8 +1810,7 @@ static void mmu_set_spte(struct kvm_vcpu *vcpu, u64 *shadow_pte, page_header_update_slot(vcpu->kvm, shadow_pte, gfn); if (!was_rmapped) { rmap_add(vcpu, shadow_pte, gfn, largepage); - if (!is_rmap_pte(*shadow_pte)) - kvm_release_pfn_clean(pfn); + kvm_release_pfn_clean(pfn); } else { if (was_writeble) kvm_release_pfn_dirty(pfn); -- 1.5.6.5
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