提交 9e7b0e7f 编写于 作者: X Xiao Guangrong 提交者: Avi Kivity

KVM: MMU: fix direct sp's access corrupted

If the mapping is writable but the dirty flag is not set, we will find
the read-only direct sp and setup the mapping, then if the write #PF
occur, we will mark this mapping writable in the read-only direct sp,
now, other real read-only mapping will happily write it without #PF.

It may hurt guest's COW

Fixed by re-install the mapping when write #PF occur.
Signed-off-by: NXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
上级 5fd5387c
......@@ -325,8 +325,32 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
break;
}
if (is_shadow_present_pte(*sptep) && !is_large_pte(*sptep))
continue;
if (is_shadow_present_pte(*sptep) && !is_large_pte(*sptep)) {
struct kvm_mmu_page *child;
unsigned direct_access;
if (level != gw->level)
continue;
/*
* For the direct sp, if the guest pte's dirty bit
* changed form clean to dirty, it will corrupt the
* sp's access: allow writable in the read-only sp,
* so we should update the spte at this point to get
* a new sp with the correct access.
*/
direct_access = gw->pt_access & gw->pte_access;
if (!is_dirty_gpte(gw->ptes[gw->level - 1]))
direct_access &= ~ACC_WRITE_MASK;
child = page_header(*sptep & PT64_BASE_ADDR_MASK);
if (child->role.access == direct_access)
continue;
mmu_page_remove_parent_pte(child, sptep);
__set_spte(sptep, shadow_trap_nonpresent_pte);
kvm_flush_remote_tlbs(vcpu->kvm);
}
if (is_large_pte(*sptep)) {
rmap_remove(vcpu->kvm, sptep);
......
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