KVM: VMX: fix nested vpid for old KVM guests

Old KVM guests invoke single-context invvpid without actually checking
whether it is supported.  This was fixed by commit 518c8ae ("KVM: VMX:
Make sure single type invvpid is supported before issuing invvpid
instruction", 2010-08-01) and the patch after, but pre-2.6.36
kernels lack it including RHEL 6.

Reported-by: jmontleo@redhat.com
Tested-by: jmontleo@redhat.com
Cc: stable@vger.kernel.org
Fixes: 99b83ac893b84ed1a62ad6d1f2b6cc32026b9e85
Reviewed-by: David Matlack <dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 0ce009c..1612300 100644 (file)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2712,8 +2712,15 @@ static void nested_vmx_setup_ctls_msrs(struct vcpu_vmx *vmx)
        } else
                vmx->nested.nested_vmx_ept_caps = 0;
 
+       /*
+        * Old versions of KVM use the single-context version without
+        * checking for support, so declare that it is supported even
+        * though it is treated as global context.  The alternative is
+        * not failing the single-context invvpid, and it is worse.
+        */
        if (enable_vpid)
                vmx->nested.nested_vmx_vpid_caps = VMX_VPID_INVVPID_BIT |
+                               VMX_VPID_EXTENT_SINGLE_CONTEXT_BIT |
                                VMX_VPID_EXTENT_GLOBAL_CONTEXT_BIT;
        else
                vmx->nested.nested_vmx_vpid_caps = 0;
@@ -7475,12 +7482,17 @@ static int handle_invvpid(struct kvm_vcpu *vcpu)
        }
 
        switch (type) {
+       case VMX_VPID_EXTENT_SINGLE_CONTEXT:
+               /*
+                * Old versions of KVM use the single-context version so we
+                * have to support it; just treat it the same as all-context.
+                */
        case VMX_VPID_EXTENT_ALL_CONTEXT:
                __vmx_flush_tlb(vcpu, to_vmx(vcpu)->nested.vpid02);
                nested_vmx_succeed(vcpu);
                break;
        default:
-               /* Trap single context invalidation invvpid calls */
+               /* Trap individual address invalidation invvpid calls */
                BUG_ON(1);
                break;
        }