[PATCH 05/16] KVM: VMX: Drop initialization of IA32_FEATURE_CONTROL MSR

From: Sean Christopherson <sean.j.christopherson@intel.com>
To: "Thomas Gleixner" <tglx@linutronix.de>,
	"Ingo Molnar" <mingo@redhat.com>,
	"Borislav Petkov" <bp@alien8.de>,
	x86@kernel.org, "Peter Zijlstra" <peterz@infradead.org>,
	"Arnaldo Carvalho de Melo" <acme@kernel.org>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>,
	"Tony Luck" <tony.luck@intel.com>,
	"Tony W Wang-oc" <TonyWWang-oc@zhaoxin.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
	linux-edac@vger.kernel.org, Borislav Petkov <bp@suse.de>,
	Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Subject: [PATCH 05/16] KVM: VMX: Drop initialization of IA32_FEATURE_CONTROL MSR
Date: Fri,  4 Oct 2019 14:56:04 -0700	[thread overview]
Message-ID: <20191004215615.5479-6-sean.j.christopherson@intel.com> (raw)
In-Reply-To: <20191004215615.5479-1-sean.j.christopherson@intel.com>

Remove the code to initialize IA32_FEATURE_CONTROL MSR when KVM is
loaded now that the MSR is initialized during boot on all CPUs that
support VMX, i.e. can possibly load kvm_intel.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 arch/x86/kvm/vmx/vmx.c | 48 +++++++++++++++++-------------------------
 1 file changed, 19 insertions(+), 29 deletions(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index d4575ffb3cec..23c9e4b91b31 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2192,24 +2192,26 @@ static __init int vmx_disabled_by_bios(void)
 	u64 msr;
 
 	rdmsrl(MSR_IA32_FEATURE_CONTROL, msr);
-	if (msr & FEATURE_CONTROL_LOCKED) {
-		/* launched w/ TXT and VMX disabled */
-		if (!(msr & FEATURE_CONTROL_VMXON_ENABLED_INSIDE_SMX)
-			&& tboot_enabled())
-			return 1;
-		/* launched w/o TXT and VMX only enabled w/ TXT */
-		if (!(msr & FEATURE_CONTROL_VMXON_ENABLED_OUTSIDE_SMX)
-			&& (msr & FEATURE_CONTROL_VMXON_ENABLED_INSIDE_SMX)
-			&& !tboot_enabled()) {
-			printk(KERN_WARNING "kvm: disable TXT in the BIOS or "
-				"activate TXT before enabling KVM\n");
-			return 1;
-		}
-		/* launched w/o TXT and VMX disabled */
-		if (!(msr & FEATURE_CONTROL_VMXON_ENABLED_OUTSIDE_SMX)
-			&& !tboot_enabled())
-			return 1;
+
+	if (WARN_ON_ONCE(!(msr & FEATURE_CONTROL_LOCKED)))
+		return 1;
+
+	/* launched w/ TXT and VMX disabled */
+	if (!(msr & FEATURE_CONTROL_VMXON_ENABLED_INSIDE_SMX) &&
+	    tboot_enabled())
+		return 1;
+	/* launched w/o TXT and VMX only enabled w/ TXT */
+	if (!(msr & FEATURE_CONTROL_VMXON_ENABLED_OUTSIDE_SMX) &&
+	    (msr & FEATURE_CONTROL_VMXON_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 & FEATURE_CONTROL_VMXON_ENABLED_OUTSIDE_SMX) &&
+	    !tboot_enabled())
+		return 1;
 
 	return 0;
 }
@@ -2226,7 +2228,6 @@ static int hardware_enable(void)
 {
 	int cpu = raw_smp_processor_id();
 	u64 phys_addr = __pa(per_cpu(vmxarea, cpu));
-	u64 old, test_bits;
 
 	if (cr4_read_shadow() & X86_CR4_VMXE)
 		return -EBUSY;
@@ -2254,17 +2255,6 @@ static int hardware_enable(void)
 	 */
 	crash_enable_local_vmclear(cpu);
 
-	rdmsrl(MSR_IA32_FEATURE_CONTROL, old);
-
-	test_bits = FEATURE_CONTROL_LOCKED;
-	test_bits |= FEATURE_CONTROL_VMXON_ENABLED_OUTSIDE_SMX;
-	if (tboot_enabled())
-		test_bits |= FEATURE_CONTROL_VMXON_ENABLED_INSIDE_SMX;
-
-	if ((old & test_bits) != test_bits) {
-		/* enable and lock */
-		wrmsrl(MSR_IA32_FEATURE_CONTROL, old | test_bits);
-	}
 	kvm_cpu_vmxon(phys_addr);
 	if (enable_ept)
 		ept_sync_global();
-- 
2.22.0

