| Date | Thu, 01 Jul 2010 10:32:43 -0700 | From | Greg KH <> | Subject | [patch 137/149] KVM: MMU: Segregate shadow pages with different cr0.wp |
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2.6.32-stable review patch. If anyone has any objections, please let us know.
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From: Avi Kivity <avi@redhat.com>
When cr0.wp=0, we may shadow a gpte having u/s=1 and r/w=0 with an spte having u/s=0 and r/w=1. This allows excessive access if the guest sets cr0.wp=1 and accesses through this spte.
Fix by making cr0.wp part of the base role; we'll have different sptes for the two cases and the problem disappears.
Signed-off-by: Avi Kivity <avi@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> (cherry picked from commit 3dbe141595faa48a067add3e47bba3205b79d33c) --- arch/x86/include/asm/kvm_host.h | 1 + arch/x86/kvm/mmu.c | 3 ++- 2 files changed, 3 insertions(+), 1 deletion(-)
--- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -193,6 +193,7 @@ union kvm_mmu_page_role { unsigned invalid:1; unsigned cr4_pge:1; unsigned nxe:1; + unsigned cr0_wp:1; }; }; --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -221,7 +221,7 @@ void kvm_mmu_set_mask_ptes(u64 user_mask } EXPORT_SYMBOL_GPL(kvm_mmu_set_mask_ptes); -static int is_write_protection(struct kvm_vcpu *vcpu) +static bool is_write_protection(struct kvm_vcpu *vcpu) { return vcpu->arch.cr0 & X86_CR0_WP; } @@ -2445,6 +2445,7 @@ static int init_kvm_softmmu(struct kvm_v r = paging32_init_context(vcpu); vcpu->arch.mmu.base_role.glevels = vcpu->arch.mmu.root_level; + vcpu->arch.mmu.base_role.cr0_wp = is_write_protection(vcpu); return r; }
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