Commit 39c8c672 authored by Avi Kivity's avatar Avi Kivity
Browse files

KVM: MMU: Add gpte_valid() helper 



Move the code to check whether a gpte has changed since we fetched it into
a helper.

Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
parent a357bd22

arch/x86/kvm/paging_tmpl.h

+17 −8
Original line number Diff line number Diff line
@@ -299,6 +299,17 @@ static void FNAME(update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, 
		     gpte_to_gfn(gpte), pfn, true, true);

}



static bool FNAME(gpte_changed)(struct kvm_vcpu *vcpu,

				struct guest_walker *gw, int level)

{

	int r;

	pt_element_t curr_pte;



	r = kvm_read_guest_atomic(vcpu->kvm, gw->pte_gpa[level - 1],

				  &curr_pte, sizeof(curr_pte));

	return r || curr_pte != gw->ptes[level - 1];

}



/*

 * Fetch a shadow pte for a specific level in the paging hierarchy.

 */
@@ -312,11 +323,9 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr, 
	u64 *sptep = NULL;

	int direct;

	gfn_t table_gfn;

	int r;

	int level;

	bool dirty = is_dirty_gpte(gw->ptes[gw->level - 1]);

	unsigned direct_access;

	pt_element_t curr_pte;

	struct kvm_shadow_walk_iterator iterator;



	if (!is_present_gpte(gw->ptes[gw->level - 1]))
@@ -365,17 +374,17 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr, 
		}

		sp = kvm_mmu_get_page(vcpu, table_gfn, addr, level-1,

					       direct, access, sptep);

		if (!direct) {

			r = kvm_read_guest_atomic(vcpu->kvm,

						  gw->pte_gpa[level - 2],

						  &curr_pte, sizeof(curr_pte));

			if (r || curr_pte != gw->ptes[level - 2]) {

		if (!direct)

			/*

			 * Verify that the gpte in the page we've just write

			 * protected is still there.

			 */

			if (FNAME(gpte_changed)(vcpu, gw, level - 1)) {

				kvm_mmu_put_page(sp, sptep);

				kvm_release_pfn_clean(pfn);

				sptep = NULL;

				break;

			}

		}



		link_shadow_page(sptep, sp);

	}