KVM: s390: fix memory slot handling for KVM_SET_USER_MEMORY_REGION

[ Upstream commit 19ec166c3f39fe1d3789888a74cc95544ac266d4 ]

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@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index f538e3fac7ade9ad7a6635b9b28ee6f149e30bc1..fc7de27960e73dab4ad96d8a6c987056a6b35cd2 100644 (file)
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -4156,21 +4156,28 @@ void kvm_arch_commit_memory_region(struct kvm *kvm,
                                const struct kvm_memory_slot *new,
                                enum kvm_mr_change change)
 {
-       int rc;
-
-       /* 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;
+       int rc = 0;
 
-       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;