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authorPaolo Bonzini <pbonzini@redhat.com>2021-11-22 19:50:34 -0500
committerPaolo Bonzini <pbonzini@redhat.com>2021-11-30 03:54:14 -0500
commit17d44a96f000fe1040d4ba1c34e458c63be6b7ce (patch)
tree759824b697177936ad53c887de4604947141e8c3 /tools
parentbf42b02b19e27d6849852a41dd734af4c05e73c6 (diff)
KVM: SEV: Prohibit migration of a VM that has mirrors
VMs that mirror an encryption context rely on the owner to keep the ASID allocated. Performing a KVM_CAP_VM_MOVE_ENC_CONTEXT_FROM would cause a dangling ASID: 1. copy context from A to B (gets ref to A) 2. move context from A to L (moves ASID from A to L) 3. close L (releases ASID from L, B still references it) The right way to do the handoff instead is to create a fresh mirror VM on the destination first: 1. copy context from A to B (gets ref to A) [later] 2. close B (releases ref to A) 3. move context from A to L (moves ASID from A to L) 4. copy context from L to M So, catch the situation by adding a count of how many VMs are mirroring this one's encryption context. Fixes: 0b020f5af092 ("KVM: SEV: Add support for SEV-ES intra host migration") Message-Id: <20211123005036.2954379-11-pbonzini@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'tools')
-rw-r--r--tools/testing/selftests/kvm/x86_64/sev_migrate_tests.c37
1 files changed, 37 insertions, 0 deletions
diff --git a/tools/testing/selftests/kvm/x86_64/sev_migrate_tests.c b/tools/testing/selftests/kvm/x86_64/sev_migrate_tests.c
index d265cea5de85..29b18d565cf4 100644
--- a/tools/testing/selftests/kvm/x86_64/sev_migrate_tests.c
+++ b/tools/testing/selftests/kvm/x86_64/sev_migrate_tests.c
@@ -294,6 +294,41 @@ static void test_sev_mirror_parameters(void)
kvm_vm_free(vm_no_vcpu);
}
+static void test_sev_move_copy(void)
+{
+ struct kvm_vm *dst_vm, *sev_vm, *mirror_vm, *dst_mirror_vm;
+ int ret;
+
+ sev_vm = sev_vm_create(/* es= */ false);
+ dst_vm = aux_vm_create(true);
+ mirror_vm = aux_vm_create(false);
+ dst_mirror_vm = aux_vm_create(false);
+
+ sev_mirror_create(mirror_vm->fd, sev_vm->fd);
+ ret = __sev_migrate_from(dst_vm->fd, sev_vm->fd);
+ TEST_ASSERT(ret == -1 && errno == EBUSY,
+ "Cannot migrate VM that has mirrors. ret %d, errno: %d\n", ret,
+ errno);
+
+ /* The mirror itself can be migrated. */
+ sev_migrate_from(dst_mirror_vm->fd, mirror_vm->fd);
+ ret = __sev_migrate_from(dst_vm->fd, sev_vm->fd);
+ TEST_ASSERT(ret == -1 && errno == EBUSY,
+ "Cannot migrate VM that has mirrors. ret %d, errno: %d\n", ret,
+ errno);
+
+ /*
+ * mirror_vm is not a mirror anymore, dst_mirror_vm is. Thus,
+ * the owner can be copied as soon as dst_mirror_vm is gone.
+ */
+ kvm_vm_free(dst_mirror_vm);
+ sev_migrate_from(dst_vm->fd, sev_vm->fd);
+
+ kvm_vm_free(mirror_vm);
+ kvm_vm_free(dst_vm);
+ kvm_vm_free(sev_vm);
+}
+
int main(int argc, char *argv[])
{
if (kvm_check_cap(KVM_CAP_VM_MOVE_ENC_CONTEXT_FROM)) {
@@ -301,6 +336,8 @@ int main(int argc, char *argv[])
test_sev_migrate_from(/* es= */ true);
test_sev_migrate_locking();
test_sev_migrate_parameters();
+ if (kvm_check_cap(KVM_CAP_VM_COPY_ENC_CONTEXT_FROM))
+ test_sev_move_copy();
}
if (kvm_check_cap(KVM_CAP_VM_COPY_ENC_CONTEXT_FROM)) {
test_sev_mirror(/* es= */ false);