[PATCH v4 10/19] x86/cpu: Detect VMX features on Intel, Centaur and Zhaoxin CPUs

Sean Christopherson
2019-11-28T01:41:41Z

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>
---
arch/x86/Kconfig.cpu | 4 ++
arch/x86/include/asm/processor.h | 3 ++
arch/x86/include/asm/vmxfeatures.h | 5 +++
arch/x86/kernel/cpu/common.c | 3 ++
arch/x86/kernel/cpu/feat_ctl.c | 70 ++++++++++++++++++++++++++++++
5 files changed, 85 insertions(+)

diff --git a/arch/x86/Kconfig.cpu b/arch/x86/Kconfig.cpu
index 526425fcaedc..bc3a497c029c 100644
--- a/arch/x86/Kconfig.cpu
+++ b/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---
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index bab513404606..3324cf036dfb 100644
--- a/arch/x86/include/asm/processor.h
+++ b/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;
diff --git a/arch/x86/include/asm/vmxfeatures.h b/arch/x86/include/asm/vmxfeatures.h
index 1b96b03c1147..ab42d94e2359 100644
--- a/arch/x86/include/asm/vmxfeatures.h
+++ b/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 "",
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 9d6a35a4586e..df1eacd26443 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/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);

diff --git a/arch/x86/kernel/cpu/feat_ctl.c b/arch/x86/kernel/cpu/feat_ctl.c
index a46c9e46f937..93268bde662a 100644
--- a/arch/x86/kernel/cpu/feat_ctl.c
+++ b/arch/x86/kernel/cpu/feat_ctl.c
@@ -4,6 +4,72 @@
#include <asm/cpufeature.h>
#include <asm/msr-index.h>
#include <asm/processor.h>
+#include <asm/vmx.h>
+
+#ifdef CONFIG_X86_VMX_FEATURE_NAMES
+enum vmx_feature_leafs {
+ MISC_FEATURES = 0,
+ PRIMARY_PROC_CTLS,
+ SECONDARY_PROC_CTLS,
+ NR_VMX_FEATURE_WORDS,
+};
+
+#define 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.
+ */
+ rdmsr(MSR_IA32_VMX_PROCBASED_CTLS, ign, supported);
+ c->vmx_capability[PRIMARY_PROC_CTLS] = supported;
+
+ rdmsr_safe(MSR_IA32_VMX_PROCBASED_CTLS2, &ign, &supported);
+ c->vmx_capability[SECONDARY_PROC_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] |= F(EPT_EXECUTE_ONLY);
+ if (ept & VMX_EPT_AD_BIT)
+ c->vmx_capability[MISC_FEATURES] |= F(EPT_AD);
+ if (ept & VMX_EPT_1GB_PAGE_BIT)
+ c->vmx_capability[MISC_FEATURES] |= F(EPT_1GB);
+
+ /* Synthetic APIC features that are aggregates of multiple features. */
+ if ((c->vmx_capability[PRIMARY_PROC_CTLS] & F(VIRTUAL_TPR)) &&
+ (c->vmx_capability[SECONDARY_PROC_CTLS] & F(VIRT_APIC_ACCESSES)))
+ c->vmx_capability[MISC_FEATURES] |= F(FLEXPRIORITY);
+
+ if ((c->vmx_capability[PRIMARY_PROC_CTLS] & F(VIRTUAL_TPR)) &&
+ (c->vmx_capability[SECONDARY_PROC_CTLS] & F(APIC_REGISTER_VIRT)) &&
+ (c->vmx_capability[SECONDARY_PROC_CTLS] & F(VIRT_INTR_DELIVERY)) &&
+ (c->vmx_capability[MISC_FEATURES] & F(POSTED_INTR)))
+ c->vmx_capability[MISC_FEATURES] |= F(APICV);
+}
+#endif /* CONFIG_X86_VMX_FEATURE_NAMES */

#undef pr_fmt
#define pr_fmt(fmt) "x86/cpu: " fmt
@@ -50,5 +116,9 @@ void init_ia32_feat_ctl(struct cpuinfo_x86 *c)
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
}
}
--
2.24.0