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

arch/x86/Kconfig.cpu

@@ -391,6 +391,10 @@ config IA32_FEAT_CTL
 	def_bool y
 	depends on CPU_SUP_INTEL || CPU_SUP_CENTAUR || CPU_SUP_ZHAOXIN
 
+config X86_VMX_FEATURE_NAMES
+	def_bool y
+	depends on IA32_FEAT_CTL && X86_FEATURE_NAMES
+
 menuconfig PROCESSOR_SELECT
 	bool "Supported processor vendors" if EXPERT
 	---help---

arch/x86/include/asm/processor.h

@@ -85,6 +85,9 @@ struct cpuinfo_x86 {
 #ifdef CONFIG_X86_64
 	/* Number of 4K pages in DTLB/ITLB combined(in pages): */
 	int			x86_tlbsize;
+#endif
+#ifdef CONFIG_X86_VMX_FEATURE_NAMES
+	__u32			vmx_capability[NVMXINTS];
 #endif
 	__u8			x86_virt_bits;
 	__u8			x86_phys_bits;

arch/x86/include/asm/vmxfeatures.h

@@ -2,6 +2,11 @@
 #ifndef _ASM_X86_VMXFEATURES_H
 #define _ASM_X86_VMXFEATURES_H
 
+/*
+ * Defines VMX CPU feature bits
+ */
+#define NVMXINTS			3 /* N 32-bit words worth of info */
+
 /*
  * Note: If the comment begins with a quoted string, that string is used
  * in /proc/cpuinfo instead of the macro name.  If the string is "",

arch/x86/kernel/cpu/common.c

@@ -1449,6 +1449,9 @@ static void identify_cpu(struct cpuinfo_x86 *c)
 #endif
 	c->x86_cache_alignment = c->x86_clflush_size;
 	memset(&c->x86_capability, 0, sizeof(c->x86_capability));
+#ifdef CONFIG_X86_VMX_FEATURE_NAMES
+	memset(&c->vmx_capability, 0, sizeof(c->vmx_capability));
+#endif
 
 	generic_identify(c);
 

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
 	}
 }