KVM: x86/mmu: Only allocate shadowed translation cache for sp->role.level <= KVM_MAX_HUGEPAGE_LEVEL

Only the indirect SP with sp->role.level <= KVM_MAX_HUGEPAGE_LEVEL might
have leaf gptes, so allocation of shadowed translation cache is needed
only for it. Then, it can use sp->shadowed_translation to determine
whether to use the information in the shadowed translation cache or not.
Also, extend the WARN in FNAME(sync_spte)() to ensure that this won't
break shadow_mmu_get_sp_for_split().

Suggested-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
Link: https://lore.kernel.org/r/5b0cda8a7456cda476b14fca36414a56f921dd52.1715398655.git.houwenlong.hwl@antgroup.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

Author: bysui

arch/x86/kvm/mmu/mmu.c

@@ -719,7 +719,7 @@ static gfn_t kvm_mmu_page_get_gfn(struct kvm_mmu_page *sp, int index)
 	if (sp->role.passthrough)
 		return sp->gfn;
 
-	if (!sp->role.direct)
+	if (sp->shadowed_translation)
 		return sp->shadowed_translation[index] >> PAGE_SHIFT;
 
 	return sp->gfn + (index << ((sp->role.level - 1) * SPTE_LEVEL_BITS));
@@ -733,7 +733,7 @@ static gfn_t kvm_mmu_page_get_gfn(struct kvm_mmu_page *sp, int index)
  */
 static u32 kvm_mmu_page_get_access(struct kvm_mmu_page *sp, int index)
 {
-	if (sp_has_gptes(sp))
+	if (sp->shadowed_translation)
 		return sp->shadowed_translation[index] & ACC_ALL;
 
 	/*
@@ -754,7 +754,7 @@ static u32 kvm_mmu_page_get_access(struct kvm_mmu_page *sp, int index)
 static void kvm_mmu_page_set_translation(struct kvm_mmu_page *sp, int index,
 					 gfn_t gfn, unsigned int access)
 {
-	if (sp_has_gptes(sp)) {
+	if (sp->shadowed_translation) {
 		sp->shadowed_translation[index] = (gfn << PAGE_SHIFT) | access;
 		return;
 	}
@@ -1697,8 +1697,7 @@ static void kvm_mmu_free_shadow_page(struct kvm_mmu_page *sp)
 	hlist_del(&sp->hash_link);
 	list_del(&sp->link);
 	free_page((unsigned long)sp->spt);
-	if (!sp->role.direct)
-		free_page((unsigned long)sp->shadowed_translation);
+	free_page((unsigned long)sp->shadowed_translation);
 	kmem_cache_free(mmu_page_header_cache, sp);
 }
 
@@ -2200,7 +2199,7 @@ static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm *kvm,
 
 	sp = kvm_mmu_memory_cache_alloc(caches->page_header_cache);
 	sp->spt = kvm_mmu_memory_cache_alloc(caches->shadow_page_cache);
-	if (!role.direct)
+	if (!role.direct && role.level <= KVM_MAX_HUGEPAGE_LEVEL)
 		sp->shadowed_translation = kvm_mmu_memory_cache_alloc(caches->shadowed_info_cache);
 
 	set_page_private(virt_to_page(sp->spt), (unsigned long)sp);

arch/x86/kvm/mmu/paging_tmpl.h

@@ -911,7 +911,8 @@ static int FNAME(sync_spte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, int
 	gpa_t pte_gpa;
 	gfn_t gfn;
 
-	if (WARN_ON_ONCE(sp->spt[i] == SHADOW_NONPRESENT_VALUE))
+	if (WARN_ON_ONCE(sp->spt[i] == SHADOW_NONPRESENT_VALUE ||
+			 !sp->shadowed_translation))
 		return 0;
 
 	first_pte_gpa = FNAME(get_level1_sp_gpa)(sp);