DECOMMISSION the current SEV context if binding an ASID fails after
RECEIVE_START. Per AMD's SEV API, RECEIVE_START generates a new guest
context and thus needs to be paired with DECOMMISSION:
AMD SEV API v0.24 Section 1.3.3
"The RECEIVE_START command is the only command other than the
LAUNCH_START command that generates a new guest context and guest
handle."
The missing DECOMMISSION can result in subsequent SEV launch failures due
to insufficient resource. In particular, both LAUNCH_START and
RECEIVE_START command will fail with SEV_RET_RESOURCE_LIMIT error.
Note, LAUNCH_START suffered from the same bug, but was previously fixed by
[1]. However, the same bug could come back to LAUNCH_START if RECEIVE_START
part was not fixed.
So add the sev_decommission() function in sev_receive_start.
[1] commit 934002cd660b ("KVM: SVM: Call SEV Guest Decommission if ASID
binding fails").
Cc: Alper Gun <alpergun@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Brijesh Singh <brijesh.singh@xxxxxxx>
Cc: David Rienjes <rientjes@xxxxxxxxxx>
Cc: Marc Orr <marcorr@xxxxxxxxxx>
Cc: John Allen <john.allen@xxxxxxx>
Cc: Peter Gonda <pgonda@xxxxxxxxxx>
Cc: Sean Christopherson <seanjc@xxxxxxxxxx>
Cc: Tom Lendacky <thomas.lendacky@xxxxxxx>
Cc: Vipin Sharma <vipinsh@xxxxxxxxxx>
Reviewed-by: Marc Orr <marcorr@xxxxxxxxxx>
Reviewed-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Acked-by: Brijesh Singh <brijesh.singh@xxxxxxx>
Fixes: af43cbbf954b ("KVM: SVM: Add support for KVM_SEV_RECEIVE_START command")
Signed-off-by: Mingwei Zhang <mizhang@xxxxxxxxxx>
---
arch/x86/kvm/svm/sev.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 75e0b21ad07c..55d8b9c933c3 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -1397,8 +1397,10 @@ static int sev_receive_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;
+ }
params.handle = start.handle;
if (copy_to_user((void __user *)(uintptr_t)argp->data,
--
2.33.0.464.g1972c5931b-goog
