mirrors/linux
2
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2026-07-16 14:30:06 -04:00
Code Issues Packages Projects Releases Wiki Activity

KVM: SEV: Prohibit migration of a VM that has mirrors

Browse Source 
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: 0b020f5af0 ("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>
This commit is contained in:
Paolo Bonzini
2021-11-22 19:50:34 -05:00
parent bf42b02b19
commit 17d44a96f0
3 changed files with 59 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

37
tools/testing/selftests/kvm/x86_64/sev_migrate_tests.c
View File

@@ -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);