[PATCH v3 08/19] 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
Cc: "H. Peter Anvin" <hpa@zytor.com>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Arnaldo Carvalho de Melo" <acme@kernel.org>,
	"Mark Rutland" <mark.rutland@arm.com>,
	"Alexander Shishkin" <alexander.shishkin@linux.intel.com>,
	"Jiri Olsa" <jolsa@redhat.com>,
	"Namhyung Kim" <namhyung@kernel.org>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>,
	"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>,
	"Tony Luck" <tony.luck@intel.com>,
	"Tony W Wang-oc" <TonyWWang-oc@zhaoxin.com>,
	"Shuah Khan" <shuah@kernel.org>,
	linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
	linux-edac@vger.kernel.org, linux-kselftest@vger.kernel.org,
	"Borislav Petkov" <bp@suse.de>,
	"Jarkko Sakkinen" <jarkko.sakkinen@linux.intel.com>
Subject: [PATCH v3 08/19] KVM: VMX: Drop initialization of IA32_FEATURE_CONTROL MSR
Date: Mon, 18 Nov 2019 19:12:29 -0800	[thread overview]
Message-ID: <20191119031240.7779-9-sean.j.christopherson@intel.com> (raw)
In-Reply-To: <20191119031240.7779-1-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.

Reviewed-by: Jim Mattson <jmattson@google.com>
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 a8e2c3b74daa..e9681e3fcb63 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2195,24 +2195,26 @@ static __init int vmx_disabled_by_bios(void)
 	u64 msr;
 
 	rdmsrl(MSR_IA32_FEATURE_CONTROL, msr);
-	if (msr & FEAT_CTL_LOCKED) {
-		/* 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()) {
-			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 & FEAT_CTL_VMX_ENABLED_OUTSIDE_SMX)
-			&& !tboot_enabled())
-			return 1;
+
+	if (WARN_ON_ONCE(!(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;
 }
@@ -2229,7 +2231,6 @@ 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;
@@ -2257,17 +2258,6 @@ static int hardware_enable(void)
 	 */
 	crash_enable_local_vmclear(cpu);
 
-	rdmsrl(MSR_IA32_FEATURE_CONTROL, old);
-
-	test_bits = FEAT_CTL_LOCKED;
-	test_bits |= FEAT_CTL_VMX_ENABLED_OUTSIDE_SMX;
-	if (tboot_enabled())
-		test_bits |= FEAT_CTL_VMX_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();
-- 
2.24.0

