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Commit f59c1d2d authored by Avi Kivity's avatar Avi Kivity
Browse files

KVM: MMU: Keep going on permission error



Real hardware disregards permission errors when computing page fault error
code bit 0 (page present).  Do the same.

Reviewed-by: default avatarXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent b0eeec29
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+30 −22
Original line number Diff line number Diff line
@@ -119,21 +119,25 @@ static int FNAME(walk_addr)(struct guest_walker *walker,
{
	pt_element_t pte;
	gfn_t table_gfn;
	unsigned index, pt_access, pte_access;
	unsigned index, pt_access, uninitialized_var(pte_access);
	gpa_t pte_gpa;
	int rsvd_fault = 0;
	bool eperm, present, rsvd_fault;

	trace_kvm_mmu_pagetable_walk(addr, write_fault, user_fault,
				     fetch_fault);
walk:
	present = true;
	eperm = rsvd_fault = false;
	walker->level = vcpu->arch.mmu.root_level;
	pte = vcpu->arch.cr3;
#if PTTYPE == 64
	if (!is_long_mode(vcpu)) {
		pte = kvm_pdptr_read(vcpu, (addr >> 30) & 3);
		trace_kvm_mmu_paging_element(pte, walker->level);
		if (!is_present_gpte(pte))
			goto not_present;
		if (!is_present_gpte(pte)) {
			present = false;
			goto error;
		}
		--walker->level;
	}
#endif
@@ -151,31 +155,36 @@ static int FNAME(walk_addr)(struct guest_walker *walker,
		walker->table_gfn[walker->level - 1] = table_gfn;
		walker->pte_gpa[walker->level - 1] = pte_gpa;

		if (kvm_read_guest(vcpu->kvm, pte_gpa, &pte, sizeof(pte)))
			goto not_present;
		if (kvm_read_guest(vcpu->kvm, pte_gpa, &pte, sizeof(pte))) {
			present = false;
			break;
		}

		trace_kvm_mmu_paging_element(pte, walker->level);

		if (!is_present_gpte(pte))
			goto not_present;
		if (!is_present_gpte(pte)) {
			present = false;
			break;
		}

		rsvd_fault = is_rsvd_bits_set(vcpu, pte, walker->level);
		if (rsvd_fault)
			goto access_error;
		if (is_rsvd_bits_set(vcpu, pte, walker->level)) {
			rsvd_fault = true;
			break;
		}

		if (write_fault && !is_writable_pte(pte))
			if (user_fault || is_write_protection(vcpu))
				goto access_error;
				eperm = true;

		if (user_fault && !(pte & PT_USER_MASK))
			goto access_error;
			eperm = true;

#if PTTYPE == 64
		if (fetch_fault && (pte & PT64_NX_MASK))
			goto access_error;
			eperm = true;
#endif

		if (!(pte & PT_ACCESSED_MASK)) {
		if (!eperm && !rsvd_fault && !(pte & PT_ACCESSED_MASK)) {
			trace_kvm_mmu_set_accessed_bit(table_gfn, index,
						       sizeof(pte));
			if (FNAME(cmpxchg_gpte)(vcpu->kvm, table_gfn,
@@ -214,6 +223,9 @@ static int FNAME(walk_addr)(struct guest_walker *walker,
		--walker->level;
	}

	if (!present || eperm || rsvd_fault)
		goto error;

	if (write_fault && !is_dirty_gpte(pte)) {
		bool ret;

@@ -233,14 +245,10 @@ static int FNAME(walk_addr)(struct guest_walker *walker,
		 __func__, (u64)pte, pte_access, pt_access);
	return 1;

not_present:
error:
	walker->error_code = 0;
	goto err;

access_error:
	walker->error_code = PFERR_PRESENT_MASK;

err:
	if (present)
		walker->error_code |= PFERR_PRESENT_MASK;
	if (write_fault)
		walker->error_code |= PFERR_WRITE_MASK;
	if (user_fault)