Re: [PATCH 1/2] KVM: X86/MMU: Add sp_has_gptes()

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On 4/20/22 15:12, Lai Jiangshan wrote:
From: Lai Jiangshan <jiangshan.ljs@xxxxxxxxxxxx>

Add sp_has_gptes() which equals to !sp->role.direct currently.

Shadow page having gptes needs to be write-protected, accounted and
responded to kvm_mmu_pte_write().

Use it in these places to replace !sp->role.direct and rename
for_each_gfn_indirect_valid_sp.

-#define for_each_gfn_indirect_valid_sp(_kvm, _sp, _gfn)			\
+#define for_each_gfn_valid_sp_has_gptes(_kvm, _sp, _gfn)		\

Small nit, for_each_gfn_valid_sp_with_gptes might be a little more grammatical (not much).

  	for_each_valid_sp(_kvm, _sp,					\
  	  &(_kvm)->arch.mmu_page_hash[kvm_page_table_hashfn(_gfn)])	\
-		if ((_sp)->gfn != (_gfn) || (_sp)->role.direct) {} else
+		if ((_sp)->gfn != (_gfn) || !sp_has_gptes(_sp)) {} else
static bool kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
  			 struct list_head *invalid_list)
@@ -2112,7 +2120,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
  	sp->gfn = gfn;
  	sp->role = role;
  	hlist_add_head(&sp->hash_link, sp_list);
-	if (!direct) {
+	if (sp_has_gptes(sp)) {
  		account_shadowed(vcpu->kvm, sp);
  		if (level == PG_LEVEL_4K && kvm_vcpu_write_protect_gfn(vcpu, gfn))
  			kvm_flush_remote_tlbs_with_address(vcpu->kvm, gfn, 1);
@@ -2321,7 +2329,7 @@ static bool __kvm_mmu_prepare_zap_page(struct kvm *kvm,
  	/* Zapping children means active_mmu_pages has become unstable. */
  	list_unstable = *nr_zapped;
- if (!sp->role.invalid && !sp->role.direct)
+	if (!sp->role.invalid && sp_has_gptes(sp))
  		unaccount_shadowed(kvm, sp);
if (sp->unsync)
@@ -2501,7 +2509,7 @@ int kvm_mmu_unprotect_page(struct kvm *kvm, gfn_t gfn)
  	pgprintk("%s: looking for gfn %llx\n", __func__, gfn);
  	r = 0;
  	write_lock(&kvm->mmu_lock);
-	for_each_gfn_indirect_valid_sp(kvm, sp, gfn) {
+	for_each_gfn_valid_sp_has_gptes(kvm, sp, gfn) {
  		pgprintk("%s: gfn %llx role %x\n", __func__, gfn,
  			 sp->role.word);
  		r = 1;
@@ -2563,7 +2571,7 @@ int mmu_try_to_unsync_pages(struct kvm *kvm, const struct kvm_memory_slot *slot,
  	 * that case, KVM must complete emulation of the guest TLB flush before
  	 * allowing shadow pages to become unsync (writable by the guest).
  	 */
-	for_each_gfn_indirect_valid_sp(kvm, sp, gfn) {
+	for_each_gfn_valid_sp_has_gptes(kvm, sp, gfn) {
  		if (!can_unsync)
  			return -EPERM;
@@ -5311,7 +5319,7 @@ static void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, ++vcpu->kvm->stat.mmu_pte_write; - for_each_gfn_indirect_valid_sp(vcpu->kvm, sp, gfn) {
+	for_each_gfn_valid_sp_has_gptes(vcpu->kvm, sp, gfn) {
  		if (detect_write_misaligned(sp, gpa, bytes) ||
  		      detect_write_flooding(sp)) {
  			kvm_mmu_prepare_zap_page(vcpu->kvm, sp, &invalid_list);




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