[PATCH 4.4 017/210] KVM: VMX: fix nested vpid for old KVM guests

From: Greg Kroah-Hartman
Date: Sun Apr 10 2016 - 16:12:35 EST


4.4-stable review patch. If anyone has any objections, please let me know.

------------------

From: Paolo Bonzini <pbonzini@xxxxxxxxxx>

commit ef697a712a6165aea7779c295604b099e8bfae2e upstream.

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@xxxxxxxxxx
Tested-by: jmontleo@xxxxxxxxxx
Fixes: 99b83ac893b84ed1a62ad6d1f2b6cc32026b9e85
Reviewed-by: David Matlack <dmatlack@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
arch/x86/kvm/vmx.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)

--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2637,8 +2637,15 @@ static void nested_vmx_setup_ctls_msrs(s
} 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;
@@ -7416,12 +7423,17 @@ static int handle_invvpid(struct kvm_vcp
}

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;
}