KVM: MMU: mode specific sync_page
Examine guest pagetable and bring the shadow back in sync. Caller is responsible
for local TLB flush before re-entering guest mode.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index e9fbaa4..776fb6d 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -507,6 +507,60 @@
}
}
+/*
+ * Using the cached information from sp->gfns is safe because:
+ * - The spte has a reference to the struct page, so the pfn for a given gfn
+ * can't change unless all sptes pointing to it are nuked first.
+ * - Alias changes zap the entire shadow cache.
+ */
+static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
+{
+ int i, offset, nr_present;
+
+ offset = nr_present = 0;
+
+ if (PTTYPE == 32)
+ offset = sp->role.quadrant << PT64_LEVEL_BITS;
+
+ for (i = 0; i < PT64_ENT_PER_PAGE; i++) {
+ unsigned pte_access;
+ pt_element_t gpte;
+ gpa_t pte_gpa;
+ gfn_t gfn = sp->gfns[i];
+
+ if (!is_shadow_present_pte(sp->spt[i]))
+ continue;
+
+ pte_gpa = gfn_to_gpa(sp->gfn);
+ pte_gpa += (i+offset) * sizeof(pt_element_t);
+
+ if (kvm_read_guest_atomic(vcpu->kvm, pte_gpa, &gpte,
+ sizeof(pt_element_t)))
+ return -EINVAL;
+
+ if (gpte_to_gfn(gpte) != gfn || !is_present_pte(gpte) ||
+ !(gpte & PT_ACCESSED_MASK)) {
+ u64 nonpresent;
+
+ rmap_remove(vcpu->kvm, &sp->spt[i]);
+ if (is_present_pte(gpte))
+ nonpresent = shadow_trap_nonpresent_pte;
+ else
+ nonpresent = shadow_notrap_nonpresent_pte;
+ set_shadow_pte(&sp->spt[i], nonpresent);
+ continue;
+ }
+
+ nr_present++;
+ pte_access = sp->role.access & FNAME(gpte_access)(vcpu, gpte);
+ set_spte(vcpu, &sp->spt[i], pte_access, 0, 0,
+ is_dirty_pte(gpte), 0, gfn,
+ spte_to_pfn(sp->spt[i]), true);
+ }
+
+ return !nr_present;
+}
+
#undef pt_element_t
#undef guest_walker
#undef shadow_walker