linux-kernel - [tip: x86/cpu] KVM: VMX: Check for full VMX support when verifying CPU compatibility

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Message-ID: <157899701164.1022.11587224751821960742.tip-bot2@tip-bot2>
Date:   Tue, 14 Jan 2020 10:16:51 -0000
From:   "tip-bot2 for Sean Christopherson" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Sean Christopherson <sean.j.christopherson@...el.com>,
        Borislav Petkov <bp@...e.de>, x86 <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: [tip: x86/cpu] KVM: VMX: Check for full VMX support when verifying
 CPU compatibility

The following commit has been merged into the x86/cpu branch of tip:

Commit-ID:     ff10e22e65f2b4d5d09805dd9e7194b93e303eb1
Gitweb:        https://git.kernel.org/tip/ff10e22e65f2b4d5d09805dd9e7194b93e303eb1
Author:        Sean Christopherson <sean.j.christopherson@...el.com>
AuthorDate:    Fri, 20 Dec 2019 20:45:10 -08:00
Committer:     Borislav Petkov <bp@...e.de>
CommitterDate: Mon, 13 Jan 2020 19:26:58 +01:00

KVM: VMX: Check for full VMX support when verifying CPU compatibility

Explicitly check the current CPU's IA32_FEAT_CTL and VMX feature flags
when verifying compatibility across physical CPUs.  This effectively
adds a check on IA32_FEAT_CTL to ensure that VMX is fully enabled on
all CPUs.

Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
Signed-off-by: Borislav Petkov <bp@...e.de>
Link: https://lkml.kernel.org/r/20191221044513.21680-17-sean.j.christopherson@intel.com
---
 arch/x86/kvm/vmx/vmx.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 06e0e52..cdb4bf5 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6838,6 +6838,12 @@ static int __init vmx_check_processor_compat(void)
 	struct vmcs_config vmcs_conf;
 	struct vmx_capability vmx_cap;
 
+	if (!this_cpu_has(X86_FEATURE_MSR_IA32_FEAT_CTL) ||
+	    !this_cpu_has(X86_FEATURE_VMX)) {
+		pr_err("kvm: VMX is disabled on CPU %d\n", smp_processor_id());
+		return -EIO;
+	}
+
 	if (setup_vmcs_config(&vmcs_conf, &vmx_cap) < 0)
 		return -EIO;
 	if (nested)