4.20-stable review patch. If anyone has any objections, please let me know.
------------------
[ Upstream commit 3f14a89d1132dcae3c8ce6721c6ef51f6e6d9b5f ]
By code inspection, it was found that multiple calls to KVM_SEV_INIT
could deplete asid bits and overwrite kvm_sev_info's regions_list.
Multiple calls to KVM_SVM_INIT is not likely to occur with QEMU, but this
should likely be fixed anyway.
This code is serialized by kvm->lock.
Fixes: 1654efcbc431 ("KVM: SVM: Add KVM_SEV_INIT command")
Reported-by: Cfir Cohen <cfir@xxxxxxxxxx>
Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
Signed-off-by: Radim Krčmář <rkrcmar@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
arch/x86/kvm/svm.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 11641d9e7f6f..13baba9d1cc1 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -6255,6 +6255,9 @@ static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)
int asid, ret;
ret = -EBUSY;
+ if (unlikely(sev->active))
+ return ret;
+
asid = sev_asid_new();
if (asid < 0)
return ret;
--
2.19.1
