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| author | Marcelo Tosatti <mtosatti@redhat.com> | 2008-09-23 13:18:32 -0300 |
|---|---|---|
| committer | Avi Kivity <avi@redhat.com> | 2008-10-15 14:25:18 +0200 |
| commit | 38187c830cab84daecb41169948467f1f19317e3 (patch) | |
| tree | e2566ec17957f604db89ae0f580aa94f80bad592 /arch/x86 | |
| parent | a378b4e64c0fef2d9e53214db167878b7673a7a3 (diff) | |
| download | linux-38187c830cab84daecb41169948467f1f19317e3.tar.bz2 | |
KVM: MMU: do not write-protect large mappings
There is not much point in write protecting large mappings. This
can only happen when a page is shadowed during the window between
is_largepage_backed and mmu_lock acquision. Zap the entry instead, so
the next pagefault will find a shadowed page via is_largepage_backed and
fallback to 4k translations.
Simplifies out of sync shadow.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/kvm/mmu.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 23752ef0839c..731e6fe9cb07 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -1180,11 +1180,16 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *shadow_pte, || (write_fault && !is_write_protection(vcpu) && !user_fault)) { struct kvm_mmu_page *shadow; + if (largepage && has_wrprotected_page(vcpu->kvm, gfn)) { + ret = 1; + spte = shadow_trap_nonpresent_pte; + goto set_pte; + } + spte |= PT_WRITABLE_MASK; shadow = kvm_mmu_lookup_page(vcpu->kvm, gfn); - if (shadow || - (largepage && has_wrprotected_page(vcpu->kvm, gfn))) { + if (shadow) { pgprintk("%s: found shadow page for %lx, marking ro\n", __func__, gfn); ret = 1; @@ -1197,6 +1202,7 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *shadow_pte, if (pte_access & ACC_WRITE_MASK) mark_page_dirty(vcpu->kvm, gfn); +set_pte: set_shadow_pte(shadow_pte, spte); return ret; } |