On 24/05/2019 16.06, Christian Borntraeger wrote:
> kselftests exposed a problem in the s390 handling for memory slots.
> Right now we only do proper memory slot handling for creation of new
> memory slots. Neither MOVE, nor DELETION are handled properly. Let us
> implement those.
>
> Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
> ---
> arch/s390/kvm/kvm-s390.c | 35 +++++++++++++++++++++--------------
> 1 file changed, 21 insertions(+), 14 deletions(-)
>
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index 871d2e99b156..6ec0685ab2c7 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -4525,21 +4525,28 @@ void kvm_arch_commit_memory_region(struct kvm *kvm,
> const struct kvm_memory_slot *new,
> enum kvm_mr_change change)
> {
> - int rc;
> + int rc = 0;
>
> - /* If the basics of the memslot do not change, we do not want
> - * to update the gmap. Every update causes several unnecessary
> - * segment translation exceptions. This is usually handled just
> - * fine by the normal fault handler + gmap, but it will also
> - * cause faults on the prefix page of running guest CPUs.
> - */
> - if (old->userspace_addr == mem->userspace_addr &&
> - old->base_gfn * PAGE_SIZE == mem->guest_phys_addr &&
> - old->npages * PAGE_SIZE == mem->memory_size)
> - return;
This check is now gone in the new code. Maybe mention the reason in the
patch description?
> - rc = gmap_map_segment(kvm->arch.gmap, mem->userspace_addr,
> - mem->guest_phys_addr, mem->memory_size);
> + switch (change) {
> + case KVM_MR_DELETE:
> + rc = gmap_unmap_segment(kvm->arch.gmap, old->base_gfn * PAGE_SIZE,
> + old->npages * PAGE_SIZE);
> + break;
> + case KVM_MR_MOVE:
> + rc = gmap_unmap_segment(kvm->arch.gmap, old->base_gfn * PAGE_SIZE,
> + old->npages * PAGE_SIZE);
> + if (rc)
> + break;
> + /* FALLTHROUGH */
> + case KVM_MR_CREATE:
> + rc = gmap_map_segment(kvm->arch.gmap, mem->userspace_addr,
> + mem->guest_phys_addr, mem->memory_size);
> + break;
> + case KVM_MR_FLAGS_ONLY:
> + break;
> + default:
> + WARN(1, "Unknown KVM MR CHANGE: %d\n", change);
> + }
> if (rc)
> pr_warn("failed to commit memory region\n");
> return;
>
Looks good to me, but I'm not an expert in this area, so FWIW a weak:
Reviewed-by: Thomas Huth <thuth@xxxxxxxxxx>
