[patch] kvm: sev: Fail KVM_SEV_INIT if already initialized

* [patch] kvm: sev: Fail KVM_SEV_INIT if already initialized
@ 2019-01-02 20:56 David Rientjes
  2019-01-02 21:44 ` Singh, Brijesh
  2019-01-11 13:50 ` Radim Krčmář
  0 siblings, 2 replies; 3+ messages in thread
From: David Rientjes @ 2019-01-02 20:56 UTC (permalink / raw)
  To: Brijesh Singh, Joerg Roedel, Paolo Bonzini, Radim Krčmář
  Cc: Thomas Lendacky, Thomas Gleixner, Ingo Molnar, Borislav Petkov,
	x86, kvm, linux-kernel

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@google.com>
Signed-off-by: David Rientjes <rientjes@google.com>
---
 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
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -6278,6 +6278,9 @@ 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;

^ permalink raw reply	[flat|nested] 3+ messages in thread