Re: [PATCH v3 3/8] KVM: mmu: Refactor memslot copy

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On 06.05.21 20:42, Ben Gardon wrote:
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.

Signed-off-by: Ben Gardon <bgardon@xxxxxxxxxx>
---
  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 2799c6660cce..c8010f55e368 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);

no need for the extra set of parentheses

+}
+
+static void kvm_copy_memslots(struct kvm_memslots *from,
+			      struct kvm_memslots *to)
+{
+	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(old, slots);
return slots;
  }


Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>

--
Thanks,

David / dhildenb




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