From fbc5d139bb92e6822e4c000f97631a072d8babf9 Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Mon, 15 Mar 2010 13:59:56 +0200 Subject: [PATCH] KVM: MMU: Do not instantiate nontrapping spte on unsync page The update_pte() path currently uses a nontrapping spte when a nonpresent (or nonaccessed) gpte is written. This is fine since at present it is only used on sync pages. However, on an unsync page this will cause an endless fault loop as the guest is under no obligation to invlpg a gpte that transitions from nonpresent to present. Needed for the next patch which reinstates update_pte() on invlpg. Signed-off-by: Avi Kivity Signed-off-by: Marcelo Tosatti --- arch/x86/kvm/paging_tmpl.h | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h index 81eab9a50e6a..4b37e1acd375 100644 --- a/arch/x86/kvm/paging_tmpl.h +++ b/arch/x86/kvm/paging_tmpl.h @@ -258,11 +258,17 @@ static void FNAME(update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *page, pt_element_t gpte; unsigned pte_access; pfn_t pfn; + u64 new_spte; gpte = *(const pt_element_t *)pte; if (~gpte & (PT_PRESENT_MASK | PT_ACCESSED_MASK)) { - if (!is_present_gpte(gpte)) - __set_spte(spte, shadow_notrap_nonpresent_pte); + if (!is_present_gpte(gpte)) { + if (page->unsync) + new_spte = shadow_trap_nonpresent_pte; + else + new_spte = shadow_notrap_nonpresent_pte; + __set_spte(spte, new_spte); + } return; } pgprintk("%s: gpte %llx spte %p\n", __func__, (u64)gpte, spte);