[PATCH 2/2] x86: Extended cpuinfo to show virtualization HW features

Sheng Yang
2008-09-09T06:52:03Z

The hardware virtualization technology evolves very fast. But currently
it's hard to tell if your CPU support a certain kind of HW technology
without digging into the source code.

The patch add a new catagory in "flags" under /proc/cpuinfo. Now "flags"
can indicate the (important) HW virtulization features the CPU supported
as well.

Current implementation just cover Intel VMX side.

Signed-off-by: Sheng Yang <sheng.yang@intel.com>
---
arch/x86/kernel/cpu/common.c | 45 ++++++++++++++++++++++++++++++++++++++++++
include/asm-x86/cpufeature.h | 9 +++++++-
2 files changed, 53 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index f7c1964..01432e2 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -581,6 +581,50 @@ static void __cpuinit detect_nopl(struct cpuinfo_x86 *c)
}
}

+static void __cpuinit detect_vmx_virtcap(struct cpuinfo_x86 *c)
+{
+ /* Intel VMX MSR indicated features */
+#define X86_VMX_FEATURE_PROC_CTLS_TPR_SHADOW 0x00200000
+#define X86_VMX_FEATURE_PROC_CTLS_VNMI 0x00400000
+#define X86_VMX_FEATURE_PROC_CTLS_2ND_CTLS 0x80000000
+#define X86_VMX_FEATURE_PROC_CTLS2_VIRT_APIC 0x00000001
+#define X86_VMX_FEATURE_PROC_CTLS2_EPT 0x00000002
+#define X86_VMX_FEATURE_PROC_CTLS2_VPID 0x00000020
+
+ u32 vmx_msr_low, vmx_msr_high, msr_ctl, msr_ctl2;
+
+ clear_cpu_cap(c, X86_FEATURE_TPR_SHADOW);
+ clear_cpu_cap(c, X86_FEATURE_VNMI);
+ clear_cpu_cap(c, X86_FEATURE_FLEXPRIORITY);
+ clear_cpu_cap(c, X86_FEATURE_EPT);
+ clear_cpu_cap(c, X86_FEATURE_VPID);
+
+ rdmsr(MSR_IA32_VMX_PROCBASED_CTLS, vmx_msr_low, vmx_msr_high);
+ msr_ctl = vmx_msr_high | vmx_msr_low;
+ if (msr_ctl & X86_VMX_FEATURE_PROC_CTLS_TPR_SHADOW)
+ set_cpu_cap(c, X86_FEATURE_TPR_SHADOW);
+ if (msr_ctl & X86_VMX_FEATURE_PROC_CTLS_VNMI)
+ set_cpu_cap(c, X86_FEATURE_VNMI);
+ if (msr_ctl & X86_VMX_FEATURE_PROC_CTLS_2ND_CTLS) {
+ rdmsr(MSR_IA32_VMX_PROCBASED_CTLS2,
+ vmx_msr_low, vmx_msr_high);
+ msr_ctl2 = vmx_msr_high | vmx_msr_low;
+ if ((msr_ctl2 & X86_VMX_FEATURE_PROC_CTLS2_VIRT_APIC) &&
+ (msr_ctl & X86_VMX_FEATURE_PROC_CTLS_TPR_SHADOW))
+ set_cpu_cap(c, X86_FEATURE_FLEXPRIORITY);
+ if (msr_ctl2 & X86_VMX_FEATURE_PROC_CTLS2_EPT)
+ set_cpu_cap(c, X86_FEATURE_EPT);
+ if (msr_ctl2 & X86_VMX_FEATURE_PROC_CTLS2_VPID)
+ set_cpu_cap(c, X86_FEATURE_VPID);
+ }
+}
+
+static void __cpuinit detect_virtcap(struct cpuinfo_x86 *c)
+{
+ if (cpu_has(c, X86_FEATURE_VMX))
+ detect_vmx_virtcap(c);
+}
+
static void __cpuinit generic_identify(struct cpuinfo_x86 *c)
{
if (!have_cpuid_p())
@@ -613,6 +657,7 @@ static void __cpuinit generic_identify(struct cpuinfo_x86 *c)

init_scattered_cpuid_features(c);
detect_nopl(c);
+ detect_virtcap(c);
}

/*
diff --git a/include/asm-x86/cpufeature.h b/include/asm-x86/cpufeature.h
index 7ac4d93..8d45690 100644
--- a/include/asm-x86/cpufeature.h
+++ b/include/asm-x86/cpufeature.h
@@ -6,7 +6,7 @@

#include <asm/required-features.h>

-#define NCAPINTS 8 /* N 32-bit words worth of info */
+#define NCAPINTS 9 /* N 32-bit words worth of info */

/*
* Note: If the comment begins with a quoted string, that string is used
@@ -150,6 +150,13 @@
*/
#define X86_FEATURE_IDA (7*32+ 0) /* Intel Dynamic Acceleration */

+/* Virtualization flags: Linux defined */
+#define X86_FEATURE_TPR_SHADOW (8*32+ 0) /* Intel TPR Shadow */
+#define X86_FEATURE_VNMI (8*32+ 1) /* Intel Virtual NMI */
+#define X86_FEATURE_FLEXPRIORITY (8*32+ 2) /* Intel FlexPriority */
+#define X86_FEATURE_EPT (8*32+ 3) /* Intel Extended Page Table */
+#define X86_FEATURE_VPID (8*32+ 4) /* Intel Virtual Processor ID */
+
#if defined(__KERNEL__) && !defined(__ASSEMBLY__)

#include <linux/bitops.h>
--
1.5.4.5