[PATCH 07/23] KVM: x86/mmu: Move huge page split sp allocation code to mmu.c

[David Matlack <dmatlack@xxxxxxxxxx>]

Move the code that allocates a new shadow page for splitting huge pages
into mmu.c. Currently this code is only used by the TDP MMU but it will
be reused in subsequent commits to also split huge pages mapped by the
shadow MMU.

No functional change intended.

Signed-off-by: David Matlack <dmatlack@xxxxxxxxxx>
---
 arch/x86/kvm/mmu/mmu.c          | 26 ++++++++++++++++++++++++++
 arch/x86/kvm/mmu/mmu_internal.h |  2 ++
 arch/x86/kvm/mmu/tdp_mmu.c      | 23 ++---------------------
 3 files changed, 30 insertions(+), 21 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index d4f90a10b652..3acdf372fa9a 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1730,6 +1730,32 @@ static struct kvm_mmu_page *kvm_mmu_alloc_sp(struct kvm_vcpu *vcpu, bool direct)
 	return sp;
 }
 
+/*
+ * Allocate a new shadow page using the provided GFP flags to split a huge page.
+ *
+ * Huge page splitting always uses direct shadow pages since the huge page is
+ * being mapped directly with a lower level page table. Thus there's no need to
+ * allocate the gfns array.
+ */
+struct kvm_mmu_page *kvm_mmu_alloc_direct_sp_for_split(gfp_t gfp)
+{
+	struct kvm_mmu_page *sp;
+
+	gfp |= __GFP_ZERO;
+
+	sp = kmem_cache_alloc(mmu_page_header_cache, gfp);
+	if (!sp)
+		return NULL;
+
+	sp->spt = (void *)__get_free_page(gfp);
+	if (!sp->spt) {
+		kmem_cache_free(mmu_page_header_cache, sp);
+		return NULL;
+	}
+
+	return sp;
+}
+
 static void mark_unsync(u64 *spte);
 static void kvm_mmu_mark_parents_unsync(struct kvm_mmu_page *sp)
 {
diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h
index da6166b5c377..2c80028695ca 100644
--- a/arch/x86/kvm/mmu/mmu_internal.h
+++ b/arch/x86/kvm/mmu/mmu_internal.h
@@ -160,4 +160,6 @@ void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc);
 void account_huge_nx_page(struct kvm *kvm, struct kvm_mmu_page *sp);
 void unaccount_huge_nx_page(struct kvm *kvm, struct kvm_mmu_page *sp);
 
+struct kvm_mmu_page *kvm_mmu_alloc_direct_sp_for_split(gfp_t gfp);
+
 #endif /* __KVM_X86_MMU_INTERNAL_H */
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 8def8f810cb0..0d58c3d15894 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -1263,25 +1263,6 @@ bool kvm_tdp_mmu_wrprot_slot(struct kvm *kvm,
 	return spte_set;
 }
 
-static struct kvm_mmu_page *__tdp_mmu_alloc_sp_for_split(gfp_t gfp)
-{
-	struct kvm_mmu_page *sp;
-
-	gfp |= __GFP_ZERO;
-
-	sp = kmem_cache_alloc(mmu_page_header_cache, gfp);
-	if (!sp)
-		return NULL;
-
-	sp->spt = (void *)__get_free_page(gfp);
-	if (!sp->spt) {
-		kmem_cache_free(mmu_page_header_cache, sp);
-		return NULL;
-	}
-
-	return sp;
-}
-
 static struct kvm_mmu_page *tdp_mmu_alloc_sp_for_split(struct kvm *kvm,
 						       struct tdp_iter *iter,
 						       bool shared)
@@ -1297,7 +1278,7 @@ static struct kvm_mmu_page *tdp_mmu_alloc_sp_for_split(struct kvm *kvm,
 	 * If this allocation fails we drop the lock and retry with reclaim
 	 * allowed.
 	 */
-	sp = __tdp_mmu_alloc_sp_for_split(GFP_NOWAIT | __GFP_ACCOUNT);
+	sp = kvm_mmu_alloc_direct_sp_for_split(GFP_NOWAIT | __GFP_ACCOUNT);
 	if (sp)
 		return sp;
 
@@ -1309,7 +1290,7 @@ static struct kvm_mmu_page *tdp_mmu_alloc_sp_for_split(struct kvm *kvm,
 		write_unlock(&kvm->mmu_lock);
 
 	iter->yielded = true;
-	sp = __tdp_mmu_alloc_sp_for_split(GFP_KERNEL_ACCOUNT);
+	sp = kvm_mmu_alloc_direct_sp_for_split(GFP_KERNEL_ACCOUNT);
 
 	if (shared)
 		read_lock(&kvm->mmu_lock);
-- 
2.35.0.rc2.247.g8bbb082509-goog