On Tue, May 11, 2021, 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.
>
> Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
> 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 6b4feb92dc79..9e106742b388 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)
Can we call this kvm_calc_memslots_size()? This doesn't actually return the
true size of a given memslots instance since the allocated size may be greater
than the size computed by looking at used_slots.
> +{
> + return sizeof(struct kvm_memslots) +
> + (sizeof(struct kvm_memory_slot) * slots);
> +}
> +
> +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;
> }
> --
> 2.31.1.607.g51e8a6a459-goog
>
