struct list_head *invalid_list,
int *nr_zapped)
{
- bool list_unstable;
+ bool list_unstable, zapped_root = false;
trace_kvm_mmu_prepare_zap_page(sp);
++kvm->stat.mmu_shadow_zapped;
* in kvm_mmu_zap_all_fast(). Note, is_obsolete_sp() also
* treats invalid shadow pages as being obsolete.
*/
- if (!is_obsolete_sp(kvm, sp))
- kvm_make_all_cpus_request(kvm, KVM_REQ_MMU_RELOAD);
+ zapped_root = !is_obsolete_sp(kvm, sp);
}
if (sp->lpage_disallowed)
unaccount_huge_nx_page(kvm, sp);
sp->role.invalid = 1;
+
+ /*
+ * Make the request to free obsolete roots after marking the root
+ * invalid, otherwise other vCPUs may not see it as invalid.
+ */
+ if (zapped_root)
+ kvm_make_all_cpus_request(kvm, KVM_REQ_MMU_FREE_OBSOLETE_ROOTS);
return list_unstable;
}
* previous root, then __kvm_mmu_prepare_zap_page() signals all vCPUs
* to reload even if no vCPU is actively using the root.
*/
- if (!sp && kvm_test_request(KVM_REQ_MMU_RELOAD, vcpu))
+ if (!sp && kvm_test_request(KVM_REQ_MMU_FREE_OBSOLETE_ROOTS, vcpu))
return true;
return fault->slot &&
/*
* It's possible that the cached previous root page is obsolete because
* of a change in the MMU generation number. However, changing the
- * generation number is accompanied by KVM_REQ_MMU_RELOAD, which will
- * free the root set here and allocate a new one.
+ * generation number is accompanied by KVM_REQ_MMU_FREE_OBSOLETE_ROOTS,
+ * which will free the root set here and allocate a new one.
*/
kvm_make_request(KVM_REQ_LOAD_MMU_PGD, vcpu);
vcpu_clear_mmio_info(vcpu, MMIO_GVA_ANY);
}
+static bool is_obsolete_root(struct kvm *kvm, hpa_t root_hpa)
+{
+ struct kvm_mmu_page *sp;
+
+ if (!VALID_PAGE(root_hpa))
+ return false;
+
+ /*
+ * When freeing obsolete roots, treat roots as obsolete if they don't
+ * have an associated shadow page. This does mean KVM will get false
+ * positives and free roots that don't strictly need to be freed, but
+ * such false positives are relatively rare:
+ *
+ * (a) only PAE paging and nested NPT has roots without shadow pages
+ * (b) remote reloads due to a memslot update obsoletes _all_ roots
+ * (c) KVM doesn't track previous roots for PAE paging, and the guest
+ * is unlikely to zap an in-use PGD.
+ */
+ sp = to_shadow_page(root_hpa);
+ return !sp || is_obsolete_sp(kvm, sp);
+}
+
+static void __kvm_mmu_free_obsolete_roots(struct kvm *kvm, struct kvm_mmu *mmu)
+{
+ unsigned long roots_to_free = 0;
+ int i;
+
+ if (is_obsolete_root(kvm, mmu->root.hpa))
+ roots_to_free |= KVM_MMU_ROOT_CURRENT;
+
+ for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) {
+ if (is_obsolete_root(kvm, mmu->root.hpa))
+ roots_to_free |= KVM_MMU_ROOT_PREVIOUS(i);
+ }
+
+ if (roots_to_free)
+ kvm_mmu_free_roots(kvm, mmu, roots_to_free);
+}
+
+void kvm_mmu_free_obsolete_roots(struct kvm_vcpu *vcpu)
+{
+ __kvm_mmu_free_obsolete_roots(vcpu->kvm, &vcpu->arch.root_mmu);
+ __kvm_mmu_free_obsolete_roots(vcpu->kvm, &vcpu->arch.guest_mmu);
+}
+
static bool need_remote_flush(u64 old, u64 new)
{
if (!is_shadow_present_pte(old))
* Note: we need to do this under the protection of mmu_lock,
* otherwise, vcpu would purge shadow page but miss tlb flush.
*/
- kvm_make_all_cpus_request(kvm, KVM_REQ_MMU_RELOAD);
+ kvm_make_all_cpus_request(kvm, KVM_REQ_MMU_FREE_OBSOLETE_ROOTS);
kvm_zap_obsolete_pages(kvm);