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From: Shane Wang on 4 May 2010 22:50
Per Intel SDM 3B 20.7, for IA32_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 check the correct in/outside-SMX flag when detecting if VMX is disabled by BIOS, and to set in-SMX flag for VMXON after Intel TXT is launched in KVM.

Signed-off-by: Shane Wang <shane.wang(a)intel.com>
---
arch/x86/include/asm/msr-index.h | 5 ++--
arch/x86/kernel/tboot.c | 1
arch/x86/kvm/vmx.c | 30 ++++++++++++++++++-----------
include/linux/tboot.h | 1
4 files changed, 24 insertions(+), 13 deletions(-)

diff -r a96602743dbd arch/x86/include/asm/msr-index.h
--- a/arch/x86/include/asm/msr-index.h Thu Apr 29 11:49:08 2010 -0400
+++ b/arch/x86/include/asm/msr-index.h Wed May 05 06:28:36 2010 -0400
@@ -202,8 +202,9 @@
#define MSR_IA32_EBL_CR_POWERON 0x0000002a
#define MSR_IA32_FEATURE_CONTROL 0x0000003a

-#define FEATURE_CONTROL_LOCKED (1<<0)
-#define FEATURE_CONTROL_VMXON_ENABLED (1<<2)
+#define FEATURE_CONTROL_LOCKED (1<<0)
+#define FEATURE_CONTROL_VMXON_ENABLED_INSIDE_SMX (1<<1)
+#define FEATURE_CONTROL_VMXON_ENABLED_OUTSIDE_SMX (1<<2)

#define MSR_IA32_APICBASE 0x0000001b
#define MSR_IA32_APICBASE_BSP (1<<8)
diff -r a96602743dbd arch/x86/kernel/tboot.c
--- a/arch/x86/kernel/tboot.c Thu Apr 29 11:49:08 2010 -0400
+++ b/arch/x86/kernel/tboot.c Wed May 05 06:28:36 2010 -0400
@@ -46,6 +46,7 @@

/* Global pointer to shared data; NULL means no measured launch. */
struct tboot *tboot __read_mostly;
+EXPORT_SYMBOL(tboot);

/* timeout for APs (in secs) to enter wait-for-SIPI state during shutdown */
#define AP_WAIT_TIMEOUT 1
diff -r a96602743dbd arch/x86/kvm/vmx.c
--- a/arch/x86/kvm/vmx.c Thu Apr 29 11:49:08 2010 -0400
+++ b/arch/x86/kvm/vmx.c Wed May 05 06:28:36 2010 -0400
@@ -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"

@@ -1176,9 +1177,14 @@ static __init int vmx_disabled_by_bios(v
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 & tboot_enabled()
+ ? FEATURE_CONTROL_VMXON_ENABLED_INSIDE_SMX
+ : FEATURE_CONTROL_VMXON_ENABLED_OUTSIDE_SMX))
+ return 1;
+ }
+
+ return 0;
/* locked but not enabled */
}

@@ -1186,21 +1192,23 @@ static int hardware_enable(void *garbage
{
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)
diff -r a96602743dbd include/linux/tboot.h
--- a/include/linux/tboot.h Thu Apr 29 11:49:08 2010 -0400
+++ b/include/linux/tboot.h Wed May 05 06:28:36 2010 -0400
@@ -150,6 +150,7 @@ extern int tboot_force_iommu(void);

#else

+#define tboot_enabled() 0
#define tboot_probe() do { } while (0)
#define tboot_shutdown(shutdown_type) do { } while (0)
#define tboot_sleep(sleep_state, pm1a_control, pm1b_control) \
--
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Prev: [PATCH] sysfs-namespaces: add a high-level Documentation file
Next: Pvclock fixes , version two