[PATCH v5 3/7] KVM: mmu: Refactor memslot copy

From: Ben Gardon <bgardon@google.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: Paolo Bonzini <pbonzini@redhat.com>, Peter Xu <peterx@redhat.com>,
	Sean Christopherson <seanjc@google.com>,
	Peter Shier <pshier@google.com>,
	Yulei Zhang <yulei.kernel@gmail.com>,
	Wanpeng Li <kernellwp@gmail.com>,
	Xiao Guangrong <xiaoguangrong.eric@gmail.com>,
	Kai Huang <kai.huang@intel.com>,
	Keqian Zhu <zhukeqian1@huawei.com>,
	David Hildenbrand <david@redhat.com>,
	Ben Gardon <bgardon@google.com>
Subject: [PATCH v5 3/7] KVM: mmu: Refactor memslot copy
Date: Tue, 18 May 2021 10:34:10 -0700	[thread overview]
Message-ID: <20210518173414.450044-4-bgardon@google.com> (raw)
In-Reply-To: <20210518173414.450044-1-bgardon@google.com>

Factor out copying kvm_memslots from allocating the memory for new ones
in preparation for adding a new lock to protect the arch-specific fields
of the memslots.

No functional change intended.

Reviewed-by: David Hildenbrand <david@redhat.com>

Signed-off-by: Ben Gardon <bgardon@google.com>
---
 virt/kvm/kvm_main.c | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 6b4feb92dc79..4acd4722d729 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1306,6 +1306,18 @@ static struct kvm_memslots *install_new_memslots(struct kvm *kvm,
 	return old_memslots;
 }
 
+static size_t kvm_memslots_size(int slots)
+{
+	return sizeof(struct kvm_memslots) +
+	       (sizeof(struct kvm_memory_slot) * slots);
+}
+
+static void kvm_copy_memslots(struct kvm_memslots *to,
+			      struct kvm_memslots *from)
+{
+	memcpy(to, from, kvm_memslots_size(from->used_slots));
+}
+
 /*
  * Note, at a minimum, the current number of used slots must be allocated, even
  * when deleting a memslot, as we need a complete duplicate of the memslots for
@@ -1315,19 +1327,16 @@ static struct kvm_memslots *kvm_dup_memslots(struct kvm_memslots *old,
 					     enum kvm_mr_change change)
 {
 	struct kvm_memslots *slots;
-	size_t old_size, new_size;
-
-	old_size = sizeof(struct kvm_memslots) +
-		   (sizeof(struct kvm_memory_slot) * old->used_slots);
+	size_t new_size;
 
 	if (change == KVM_MR_CREATE)
-		new_size = old_size + sizeof(struct kvm_memory_slot);
+		new_size = kvm_memslots_size(old->used_slots + 1);
 	else
-		new_size = old_size;
+		new_size = kvm_memslots_size(old->used_slots);
 
 	slots = kvzalloc(new_size, GFP_KERNEL_ACCOUNT);
 	if (likely(slots))
-		memcpy(slots, old, old_size);
+		kvm_copy_memslots(slots, old);
 
 	return slots;
 }
-- 
2.31.1.751.gd2f1c929bd-goog

