linux-kernel - [PATCH v5 2/7] KVM: x86/mmu: Factor out allocating memslot rmap

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Date:   Tue, 18 May 2021 10:34:09 -0700
From:   Ben Gardon <bgardon@...gle.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>, Peter Xu <peterx@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Peter Shier <pshier@...gle.com>,
        Yulei Zhang <yulei.kernel@...il.com>,
        Wanpeng Li <kernellwp@...il.com>,
        Xiao Guangrong <xiaoguangrong.eric@...il.com>,
        Kai Huang <kai.huang@...el.com>,
        Keqian Zhu <zhukeqian1@...wei.com>,
        David Hildenbrand <david@...hat.com>,
        Ben Gardon <bgardon@...gle.com>
Subject: [PATCH v5 2/7] KVM: x86/mmu: Factor out allocating memslot rmap

Small refactor to facilitate allocating rmaps for all memslots at once.

No functional change expected.

Signed-off-by: Ben Gardon <bgardon@...gle.com>
---
 arch/x86/kvm/x86.c | 37 +++++++++++++++++++++++++++----------
 1 file changed, 27 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 11908beae58b..4b3d53c5fc76 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10920,10 +10920,31 @@ void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *slot)
 	kvm_page_track_free_memslot(slot);
 }
 
+static int memslot_rmap_alloc(struct kvm_memory_slot *slot,
+			      unsigned long npages)
+{
+	const int sz = sizeof(*slot->arch.rmap[0]);
+	int i;
+
+	for (i = 0; i < KVM_NR_PAGE_SIZES; ++i) {
+		int level = i + 1;
+		int lpages = gfn_to_index(slot->base_gfn + npages - 1,
+					  slot->base_gfn, level) + 1;
+
+		slot->arch.rmap[i] = kvcalloc(lpages, sz, GFP_KERNEL_ACCOUNT);
+		if (!slot->arch.rmap[i]) {
+			memslot_rmap_free(slot);
+			return -ENOMEM;
+		}
+	}
+
+	return 0;
+}
+
 static int kvm_alloc_memslot_metadata(struct kvm_memory_slot *slot,
 				      unsigned long npages)
 {
-	int i;
+	int i, r;
 
 	/*
 	 * Clear out the previous array pointers for the KVM_MR_MOVE case.  The
@@ -10932,7 +10953,11 @@ static int kvm_alloc_memslot_metadata(struct kvm_memory_slot *slot,
 	 */
 	memset(&slot->arch, 0, sizeof(slot->arch));
 
-	for (i = 0; i < KVM_NR_PAGE_SIZES; ++i) {
+	r = memslot_rmap_alloc(slot, npages);
+	if (r)
+		return r;
+
+	for (i = 1; i < KVM_NR_PAGE_SIZES; ++i) {
 		struct kvm_lpage_info *linfo;
 		unsigned long ugfn;
 		int lpages;
@@ -10941,14 +10966,6 @@ static int kvm_alloc_memslot_metadata(struct kvm_memory_slot *slot,
 		lpages = gfn_to_index(slot->base_gfn + npages - 1,
 				      slot->base_gfn, level) + 1;
 
-		slot->arch.rmap[i] =
-			kvcalloc(lpages, sizeof(*slot->arch.rmap[i]),
-				 GFP_KERNEL_ACCOUNT);
-		if (!slot->arch.rmap[i])
-			goto out_free;
-		if (i == 0)
-			continue;
-
 		linfo = kvcalloc(lpages, sizeof(*linfo), GFP_KERNEL_ACCOUNT);
 		if (!linfo)
 			goto out_free;
-- 
2.31.1.751.gd2f1c929bd-goog