On 25/06/21 00:03, Alper Gun wrote:
commit 934002cd660b035b926438244b4294e647507e13 upstream.
Send SEV_CMD_DECOMMISSION command to PSP firmware if ASID binding
fails. If a failure happens after a successful LAUNCH_START command,
a decommission command should be executed. Otherwise, guest context
will be unfreed inside the AMD SP. After the firmware will not have
memory to allocate more SEV guest context, LAUNCH_START command will
begin to fail with SEV_RET_RESOURCE_LIMIT error.
The existing code calls decommission inside sev_unbind_asid, but it is
not called if a failure happens before guest activation succeeds. If
sev_bind_asid fails, decommission is never called. PSP firmware has a
limit for the number of guests. If sev_asid_binding fails many times,
PSP firmware will not have resources to create another guest context.
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 59414c989220 ("KVM: SVM: Add support for KVM_SEV_LAUNCH_START command")
Reported-by: Peter Gonda <pgonda@xxxxxxxxxx>
Signed-off-by: Alper Gun <alpergun@xxxxxxxxxx>
Reviewed-by: Marc Orr <marcorr@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
arch/x86/kvm/svm/sev.c | 26 +++++++++++++++-----------
1 file changed, 15 insertions(+), 11 deletions(-)
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 16b10b9436dc..8112eafd45bc 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -130,9 +130,19 @@ static void sev_asid_free(int asid)
mutex_unlock(&sev_bitmap_lock);
}
+static void sev_decommission(unsigned int handle)
+{
+ struct sev_data_decommission decommission;
+
+ if (!handle)
+ return;
+
+ decommission.handle = handle;
+ sev_guest_decommission(&decommission, NULL);
+}
+
static void sev_unbind_asid(struct kvm *kvm, unsigned int handle)
{
- struct sev_data_decommission *decommission;
struct sev_data_deactivate *data;
if (!handle)
@@ -152,15 +162,7 @@ static void sev_unbind_asid(struct kvm *kvm, unsigned int handle)
kfree(data);
- decommission = kzalloc(sizeof(*decommission), GFP_KERNEL);
- if (!decommission)
- return;
-
- /* decommission handle */
- decommission->handle = handle;
- sev_guest_decommission(decommission, NULL);
-
- kfree(decommission);
+ sev_decommission(handle);
}
static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)
@@ -288,8 +290,10 @@ static int sev_launch_start(struct kvm *kvm, struct kvm_sev_cmd *argp)
/* Bind ASID to this guest */
ret = sev_bind_asid(kvm, start->handle, error);
- if (ret)
+ if (ret) {
+ sev_decommission(start->handle);
goto e_free_session;
+ }
/* return handle to userspace */
params.handle = start->handle;
NACK
for this one too.
Paolo
