On 10/06/21 19:46, Alper Gun wrote:
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>
---
arch/x86/kvm/svm/sev.c | 20 +++++++++++++++-----
1 file changed, 15 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index e0ce5da97fc2..8d36f0c73071 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -199,9 +199,19 @@ static void sev_asid_free(struct kvm_sev_info *sev)
sev->misc_cg = NULL;
}
-static void sev_unbind_asid(struct kvm *kvm, unsigned int handle)
+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_deactivate deactivate;
if (!handle)
@@ -214,9 +224,7 @@ static void sev_unbind_asid(struct kvm *kvm, unsigned int handle)
sev_guest_deactivate(&deactivate, NULL);
up_read(&sev_deactivate_lock);
- /* decommission handle */
- decommission.handle = handle;
- sev_guest_decommission(&decommission, NULL);
+ sev_decommission(handle);
}
static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)
@@ -341,8 +349,10 @@ 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;
Queued, thanks.
Paolo
