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

arch/x86/kvm/paging_tmpl.h

+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)