From: Paolo Bonzini pbonzini@redhat.com
commit 0780516a18f87e881e42ed815f189279b0a1743c upstream.
This fixes the new ept_access_test_read_only and ept_access_test_read_write testcases from vmx.flat.
The problem is that gpte_access moves bits around to switch from EPT bit order (XWR) to ACC_*_MASK bit order (RWX). This results in an incorrect exit qualification. To fix this, make pt_access and pte_access operate on raw PTE values (only with NX flipped to mean "can execute") and call gpte_access at the end of the walk. This lets us use pte_access to compute the exit qualification with XWR bit order.
Signed-off-by: Paolo Bonzini pbonzini@redhat.com Reviewed-by: Xiao Guangrong xiaoguangrong@tencent.com Signed-off-by: Radim Krčmář rkrcmar@redhat.com [bwh: Backported to 4.9: - There's no support for EPT accessed/dirty bits, so do not use have_ad flag - Adjust context] Signed-off-by: Ben Hutchings ben@decadent.org.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kvm/paging_tmpl.h | 34 +++++++++++++++++++++------------- 1 file changed, 21 insertions(+), 13 deletions(-)
--- a/arch/x86/kvm/paging_tmpl.h +++ b/arch/x86/kvm/paging_tmpl.h @@ -285,9 +285,11 @@ static int FNAME(walk_addr_generic)(stru pt_element_t pte; pt_element_t __user *uninitialized_var(ptep_user); gfn_t table_gfn; - unsigned index, pt_access, pte_access, accessed_dirty, pte_pkey; + u64 pt_access, pte_access; + unsigned index, accessed_dirty, pte_pkey; gpa_t pte_gpa; int offset; + u64 walk_nx_mask = 0; const int write_fault = access & PFERR_WRITE_MASK; const int user_fault = access & PFERR_USER_MASK; const int fetch_fault = access & PFERR_FETCH_MASK; @@ -301,6 +303,7 @@ retry_walk: pte = mmu->get_cr3(vcpu);
#if PTTYPE == 64 + walk_nx_mask = 1ULL << PT64_NX_SHIFT; if (walker->level == PT32E_ROOT_LEVEL) { pte = mmu->get_pdptr(vcpu, (addr >> 30) & 3); trace_kvm_mmu_paging_element(pte, walker->level); @@ -312,15 +315,14 @@ retry_walk: walker->max_level = walker->level; ASSERT(!(is_long_mode(vcpu) && !is_pae(vcpu)));
- accessed_dirty = PT_GUEST_ACCESSED_MASK; - pt_access = pte_access = ACC_ALL; + pte_access = ~0; ++walker->level;
do { gfn_t real_gfn; unsigned long host_addr;
- pt_access &= pte_access; + pt_access = pte_access; --walker->level;
index = PT_INDEX(addr, walker->level); @@ -363,6 +365,12 @@ retry_walk:
trace_kvm_mmu_paging_element(pte, walker->level);
+ /* + * Inverting the NX it lets us AND it like other + * permission bits. + */ + pte_access = pt_access & (pte ^ walk_nx_mask); + if (unlikely(!FNAME(is_present_gpte)(pte))) goto error;
@@ -371,14 +379,16 @@ retry_walk: goto error; }
- accessed_dirty &= pte; - pte_access = pt_access & FNAME(gpte_access)(vcpu, pte); - walker->ptes[walker->level - 1] = pte; } while (!is_last_gpte(mmu, walker->level, pte));
pte_pkey = FNAME(gpte_pkeys)(vcpu, pte); - errcode = permission_fault(vcpu, mmu, pte_access, pte_pkey, access); + accessed_dirty = pte_access & PT_GUEST_ACCESSED_MASK; + + /* Convert to ACC_*_MASK flags for struct guest_walker. */ + walker->pt_access = FNAME(gpte_access)(vcpu, pt_access ^ walk_nx_mask); + walker->pte_access = FNAME(gpte_access)(vcpu, pte_access ^ walk_nx_mask); + errcode = permission_fault(vcpu, mmu, walker->pte_access, pte_pkey, access); if (unlikely(errcode)) goto error;
@@ -395,7 +405,7 @@ retry_walk: walker->gfn = real_gpa >> PAGE_SHIFT;
if (!write_fault) - FNAME(protect_clean_gpte)(&pte_access, pte); + FNAME(protect_clean_gpte)(&walker->pte_access, pte); else /* * On a write fault, fold the dirty bit into accessed_dirty. @@ -413,10 +423,8 @@ retry_walk: goto retry_walk; }
- walker->pt_access = pt_access; - walker->pte_access = pte_access; pgprintk("%s: pte %llx pte_access %x pt_access %x\n", - __func__, (u64)pte, pte_access, pt_access); + __func__, (u64)pte, walker->pte_access, walker->pt_access); return 1;
error: @@ -444,7 +452,7 @@ error: */ if (!(errcode & PFERR_RSVD_MASK)) { vcpu->arch.exit_qualification &= 0x187; - vcpu->arch.exit_qualification |= ((pt_access & pte) & 0x7) << 3; + vcpu->arch.exit_qualification |= (pte_access & 0x7) << 3; } #endif walker->fault.address = addr;