commit cafd66595d92591e4bd25c3904e004fc6f897e2d
author Shane Wang <shane.wang@intel.com> Thu Apr 29 12:09:01 2010 -0400
committer Avi Kivity <avi@redhat.com> Wed May 19 11:36:34 2010 +0300
tree 42f38daf5d634ccf958da89de2a20937849deb92
parent f1d86e469b60f9e1afed5c17a6e723c2c9c55ceb

KVM: VMX: enable VMXON check with SMX enabled (Intel TXT)

Per document, for feature control MSR:

  Bit 1 enables VMXON in SMX operation. If the bit is clear, execution
        of VMXON in SMX operation causes a general-protection exception.
  Bit 2 enables VMXON outside SMX operation. If the bit is clear, execution
        of VMXON outside SMX operation causes a general-protection exception.

This patch is to enable this kind of check with SMX for VMXON in KVM.

Signed-off-by: Shane Wang <shane.wang@intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

arch/x86/kvm/vmx.c

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index c4f3955c..d2a47ae 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -27,6 +27,7 @@
 #include <linux/moduleparam.h>
 #include <linux/ftrace_event.h>
 #include <linux/slab.h>
+#include <linux/tboot.h>
 #include "kvm_cache_regs.h"
 #include "x86.h"
 
@@ -1272,9 +1273,16 @@
 	u64 msr;
 
 	rdmsrl(MSR_IA32_FEATURE_CONTROL, msr);
-	return (msr & (FEATURE_CONTROL_LOCKED |
-		       FEATURE_CONTROL_VMXON_ENABLED))
-	    == FEATURE_CONTROL_LOCKED;
+	if (msr & FEATURE_CONTROL_LOCKED) {
+		if (!(msr & FEATURE_CONTROL_VMXON_ENABLED_INSIDE_SMX)
+			&& tboot_enabled())
+			return 1;
+		if (!(msr & FEATURE_CONTROL_VMXON_ENABLED_OUTSIDE_SMX)
+			&& !tboot_enabled())
+			return 1;
+	}
+
+	return 0;
 	/* locked but not enabled */
 }
 
@@ -1282,21 +1290,23 @@
 {
 	int cpu = raw_smp_processor_id();
 	u64 phys_addr = __pa(per_cpu(vmxarea, cpu));
-	u64 old;
+	u64 old, test_bits;
 
 	if (read_cr4() & X86_CR4_VMXE)
 		return -EBUSY;
 
 	INIT_LIST_HEAD(&per_cpu(vcpus_on_cpu, cpu));
 	rdmsrl(MSR_IA32_FEATURE_CONTROL, old);
-	if ((old & (FEATURE_CONTROL_LOCKED |
-		    FEATURE_CONTROL_VMXON_ENABLED))
-	    != (FEATURE_CONTROL_LOCKED |
-		FEATURE_CONTROL_VMXON_ENABLED))
+
+	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 |
-		       FEATURE_CONTROL_LOCKED |
-		       FEATURE_CONTROL_VMXON_ENABLED);
+		wrmsrl(MSR_IA32_FEATURE_CONTROL, old | test_bits);
+	}
 	write_cr4(read_cr4() | X86_CR4_VMXE); /* FIXME: not cpu hotplug safe */
 	asm volatile (ASM_VMX_VMXON_RAX
 		      : : "a"(&phys_addr), "m"(phys_addr)