x86/cpu: Detect VMX features on Intel, Centaur and Zhaoxin CPUs

Add an entry in struct cpuinfo_x86 to track VMX capabilities and fill
the capabilities during IA32_FEAT_CTL MSR initialization.

Make the VMX capabilities dependent on IA32_FEAT_CTL and
X86_FEATURE_NAMES so as to avoid unnecessary overhead on CPUs that can't
possibly support VMX, or when /proc/cpuinfo is not available.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20191221044513.21680-11-sean.j.christopherson@intel.com

1 files changed, 74 insertions, 0 deletions

diff --git a/arch/x86/kernel/cpu/feat_ctl.c b/arch/x86/kernel/cpu/feat_ctl.c
index a46c9e46f937..cbd8bfe9b87b 100644
--- a/arch/x86/kernel/cpu/feat_ctl.c
+++ b/arch/x86/kernel/cpu/feat_ctl.c
@@ -4,10 +4,80 @@
 #include <asm/cpufeature.h>
 #include <asm/msr-index.h>
 #include <asm/processor.h>
+#include <asm/vmx.h>
 
 #undef pr_fmt
 #define pr_fmt(fmt)	"x86/cpu: " fmt
 
+#ifdef CONFIG_X86_VMX_FEATURE_NAMES
+enum vmx_feature_leafs {
+	MISC_FEATURES = 0,
+	PRIMARY_CTLS,
+	SECONDARY_CTLS,
+	NR_VMX_FEATURE_WORDS,
+};
+
+#define VMX_F(x) BIT(VMX_FEATURE_##x & 0x1f)
+
+static void init_vmx_capabilities(struct cpuinfo_x86 *c)
+{
+	u32 supported, funcs, ept, vpid, ign;
+
+	BUILD_BUG_ON(NVMXINTS != NR_VMX_FEATURE_WORDS);
+
+	/*
+	 * The high bits contain the allowed-1 settings, i.e. features that can
+	 * be turned on.  The low bits contain the allowed-0 settings, i.e.
+	 * features that can be turned off.  Ignore the allowed-0 settings,
+	 * if a feature can be turned on then it's supported.
+	 *
+	 * Use raw rdmsr() for primary processor controls and pin controls MSRs
+	 * as they exist on any CPU that supports VMX, i.e. we want the WARN if
+	 * the RDMSR faults.
+	 */
+	rdmsr(MSR_IA32_VMX_PROCBASED_CTLS, ign, supported);
+	c->vmx_capability[PRIMARY_CTLS] = supported;
+
+	rdmsr_safe(MSR_IA32_VMX_PROCBASED_CTLS2, &ign, &supported);
+	c->vmx_capability[SECONDARY_CTLS] = supported;
+
+	rdmsr(MSR_IA32_VMX_PINBASED_CTLS, ign, supported);
+	rdmsr_safe(MSR_IA32_VMX_VMFUNC, &ign, &funcs);
+
+	/*
+	 * Except for EPT+VPID, which enumerates support for both in a single
+	 * MSR, low for EPT, high for VPID.
+	 */
+	rdmsr_safe(MSR_IA32_VMX_EPT_VPID_CAP, &ept, &vpid);
+
+	/* Pin, EPT, VPID and VM-Func are merged into a single word. */
+	WARN_ON_ONCE(supported >> 16);
+	WARN_ON_ONCE(funcs >> 4);
+	c->vmx_capability[MISC_FEATURES] = (supported & 0xffff) |
+					   ((vpid & 0x1) << 16) |
+					   ((funcs & 0xf) << 28);
+
+	/* EPT bits are full on scattered and must be manually handled. */
+	if (ept & VMX_EPT_EXECUTE_ONLY_BIT)
+		c->vmx_capability[MISC_FEATURES] |= VMX_F(EPT_EXECUTE_ONLY);
+	if (ept & VMX_EPT_AD_BIT)
+		c->vmx_capability[MISC_FEATURES] |= VMX_F(EPT_AD);
+	if (ept & VMX_EPT_1GB_PAGE_BIT)
+		c->vmx_capability[MISC_FEATURES] |= VMX_F(EPT_1GB);
+
+	/* Synthetic APIC features that are aggregates of multiple features. */
+	if ((c->vmx_capability[PRIMARY_CTLS] & VMX_F(VIRTUAL_TPR)) &&
+	    (c->vmx_capability[SECONDARY_CTLS] & VMX_F(VIRT_APIC_ACCESSES)))
+		c->vmx_capability[MISC_FEATURES] |= VMX_F(FLEXPRIORITY);
+
+	if ((c->vmx_capability[PRIMARY_CTLS] & VMX_F(VIRTUAL_TPR)) &&
+	    (c->vmx_capability[SECONDARY_CTLS] & VMX_F(APIC_REGISTER_VIRT)) &&
+	    (c->vmx_capability[SECONDARY_CTLS] & VMX_F(VIRT_INTR_DELIVERY)) &&
+	    (c->vmx_capability[MISC_FEATURES] & VMX_F(POSTED_INTR)))
+		c->vmx_capability[MISC_FEATURES] |= VMX_F(APICV);
+}
+#endif /* CONFIG_X86_VMX_FEATURE_NAMES */
+
 void init_ia32_feat_ctl(struct cpuinfo_x86 *c)
 {
 	bool tboot = tboot_enabled();
@@ -50,5 +120,9 @@ update_caps:
 		pr_err_once("VMX (%s TXT) disabled by BIOS\n",
 			    tboot ? "inside" : "outside");
 		clear_cpu_cap(c, X86_FEATURE_VMX);
+	} else {
+#ifdef CONFIG_X86_VMX_FEATURE_NAMES
+		init_vmx_capabilities(c);
+#endif
 	}
 }