From: Paolo Bonzini <pbonzini@redhat.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Subject: [PATCH] KVM: VMX: check nested state and CR4.VMXE against SMM
Date: Thu, 20 Sep 2018 00:42:22 +0200 [thread overview]
Message-ID: <1537396942-30774-1-git-send-email-pbonzini@redhat.com> (raw)
VMX cannot be enabled under SMM, check it when CR4 is set and when nested
virtualization state is restored.
This should fix some WARNs reported by syzkaller, mostly around
alloc_shadow_vmcs.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/kvm/vmx.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index c76ca0e501cf..fc2870dddfe9 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -5398,9 +5398,10 @@ static int vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
* To use VMXON (and later other VMX instructions), a guest
* must first be able to turn on cr4.VMXE (see handle_vmon()).
* So basically the check on whether to allow nested VMX
- * is here.
+ * is here. We operate under the default treatment of SMM,
+ * so VMX cannot be enabled under SMM.
*/
- if (!nested_vmx_allowed(vcpu))
+ if (!nested_vmx_allowed(vcpu) || is_smm(vcpu))
return 1;
}
@@ -13977,6 +13978,14 @@ static int vmx_set_nested_state(struct kvm_vcpu *vcpu,
~(KVM_STATE_NESTED_SMM_GUEST_MODE | KVM_STATE_NESTED_SMM_VMXON))
return -EINVAL;
+ /*
+ * SMM temporarily disables VMX, so we cannot be in guest mode,
+ * nor can VMLAUNCH/VMRESUME be pending. Outside SMM, SMM flags
+ * must be zero.
+ */
+ if (is_smm(vcpu) ? kvm_state->flags : kvm_state->vmx.smm.flags)
+ return -EINVAL;
+
if ((kvm_state->vmx.smm.flags & KVM_STATE_NESTED_SMM_GUEST_MODE) &&
!(kvm_state->vmx.smm.flags & KVM_STATE_NESTED_SMM_VMXON))
return -EINVAL;
--
1.8.3.1
reply other threads:[~2018-09-19 22:42 UTC|newest]
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