linux-kernel - [PATCH v5 15/19] KVM: VMX: Use VMX feature flag to query BIOS enabling

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Message-Id: <20191221044513.21680-16-sean.j.christopherson@intel.com>
Date:   Fri, 20 Dec 2019 20:45:09 -0800
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org
Cc:     "H. Peter Anvin" <hpa@...or.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Tony Luck <tony.luck@...el.com>,
        Tony W Wang-oc <TonyWWang-oc@...oxin.com>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        Len Brown <lenb@...nel.org>, Shuah Khan <shuah@...nel.org>,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        linux-edac@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-kselftest@...r.kernel.org, Borislav Petkov <bp@...e.de>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Subject: [PATCH v5 15/19] KVM: VMX: Use VMX feature flag to query BIOS enabling

Replace KVM's manual checks on IA32_FEAT_CTL with a query on the boot
CPU's MSR_IA32_FEAT_CTL and VMX feature flags.  The MSR_IA32_FEAT_CTL
indicates that IA32_FEAT_CTL has been configured and that dependent
features are accurately reflected in cpufeatures, e.g. the VMX flag is
now cleared during boot if VMX isn't fully enabled via IA32_FEAT_CTL,
including the case where the MSR isn't supported.

Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
---
 arch/x86/kvm/vmx/vmx.c | 27 ++-------------------------
 1 file changed, 2 insertions(+), 25 deletions(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index a026334ffc58..06e0e5262704 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2204,31 +2204,8 @@ static __init int cpu_has_kvm_support(void)
 
 static __init int vmx_disabled_by_bios(void)
 {
-	u64 msr;
-
-	rdmsrl(MSR_IA32_FEAT_CTL, msr);
-
-	if (unlikely(!(msr & FEAT_CTL_LOCKED)))
-		return 1;
-
-	/* launched w/ TXT and VMX disabled */
-	if (!(msr & FEAT_CTL_VMX_ENABLED_INSIDE_SMX) &&
-	    tboot_enabled())
-		return 1;
-	/* launched w/o TXT and VMX only enabled w/ TXT */
-	if (!(msr & FEAT_CTL_VMX_ENABLED_OUTSIDE_SMX) &&
-	    (msr & FEAT_CTL_VMX_ENABLED_INSIDE_SMX) &&
-	    !tboot_enabled()) {
-		pr_warn("kvm: disable TXT in the BIOS or "
-			"activate TXT before enabling KVM\n");
-		return 1;
-	}
-	/* launched w/o TXT and VMX disabled */
-	if (!(msr & FEAT_CTL_VMX_ENABLED_OUTSIDE_SMX) &&
-	    !tboot_enabled())
-		return 1;
-
-	return 0;
+	return !boot_cpu_has(X86_FEATURE_MSR_IA32_FEAT_CTL) ||
+	       !boot_cpu_has(X86_FEATURE_VMX);
 }
 
 static void kvm_cpu_vmxon(u64 addr)
-- 
2.24.1