This patch exposes ERMS feature to HVM and PV guests.
The REP MOVSB/STOSB instruction can enhance fast strings attempts to
move as much of the data with larger size load/stores as possible.
Signed-off-by: Yang, Wei <wei.y.yang@xxxxxxxxx>
---
tools/libxc/xc_cpufeature.h | 1 +
tools/libxc/xc_cpuid_x86.c | 6 ++++--
xen/arch/x86/traps.c | 3 ++-
xen/include/asm-x86/cpufeature.h | 1 +
4 files changed, 8 insertions(+), 3 deletions(-)
diff -r 782bc7b2661a tools/libxc/xc_cpufeature.h
--- a/tools/libxc/xc_cpufeature.h Fri Jun 10 13:51:39 2011 +0100
+++ b/tools/libxc/xc_cpufeature.h Mon Jun 13 20:55:37 2011 +0800
@@ -125,5 +125,6 @@
/* Intel-defined CPU features, CPUID level 0x00000007:0 (ebx) */
#define X86_FEATURE_FSGSBASE 0 /* {RD,WR}{FS,GS}BASE instructions */
#define X86_FEATURE_SMEP 7 /* Supervisor Mode Execution Protection */
+#define X86_FEATURE_ERMS 9 /* Enhanced REP MOVSB/STOSB */
#endif /* __LIBXC_CPUFEATURE_H */
diff -r 782bc7b2661a tools/libxc/xc_cpuid_x86.c
--- a/tools/libxc/xc_cpuid_x86.c Fri Jun 10 13:51:39 2011 +0100
+++ b/tools/libxc/xc_cpuid_x86.c Mon Jun 13 20:55:37 2011 +0800
@@ -354,7 +354,8 @@ static void xc_cpuid_hvm_policy(
case 0x00000007: /* Intel-defined CPU features */
if ( input[1] == 0 ) {
- regs[1] &= bitmaskof(X86_FEATURE_SMEP);
+ regs[1] &= (bitmaskof(X86_FEATURE_SMEP) |
+ bitmaskof(X86_FEATURE_ERMS));
} else
regs[1] = 0;
regs[0] = regs[2] = regs[3] = 0;
@@ -477,7 +478,8 @@ static void xc_cpuid_pv_policy(
case 7:
if ( input[1] == 0 )
- regs[1] &= bitmaskof(X86_FEATURE_FSGSBASE);
+ regs[1] &= (bitmaskof(X86_FEATURE_FSGSBASE) |
+ bitmaskof(X86_FEATURE_ERMS));
else
regs[1] = 0;
regs[0] = regs[2] = regs[3] = 0;
diff -r 782bc7b2661a xen/arch/x86/traps.c
--- a/xen/arch/x86/traps.c Fri Jun 10 13:51:39 2011 +0100
+++ b/xen/arch/x86/traps.c Mon Jun 13 20:55:37 2011 +0800
@@ -815,7 +815,8 @@ static void pv_cpuid(struct cpu_user_reg
break;
case 7:
if ( regs->ecx == 0 )
- b &= cpufeat_mask(X86_FEATURE_FSGSBASE);
+ b &= (cpufeat_mask(X86_FEATURE_FSGSBASE) |
+ cpufeat_mask(X86_FEATURE_ERMS));
else
b = 0;
a = c = d = 0;
diff -r 782bc7b2661a xen/include/asm-x86/cpufeature.h
--- a/xen/include/asm-x86/cpufeature.h Fri Jun 10 13:51:39 2011 +0100
+++ b/xen/include/asm-x86/cpufeature.h Mon Jun 13 20:55:37 2011 +0800
@@ -144,6 +144,7 @@
/* Intel-defined CPU features, CPUID level 0x00000007:0 (ebx), word 7 */
#define X86_FEATURE_FSGSBASE (7*32+ 0) /* {RD,WR}{FS,GS}BASE instructions */
#define X86_FEATURE_SMEP (7*32+ 7) /* Supervisor Mode Execution
Protection */
+#define X86_FEATURE_ERMS (7*32+ 9) /* Enhanced REP MOVSB/STOSB */
#define cpu_has(c, bit) test_bit(bit, (c)->x86_capability)
#define boot_cpu_has(bit) test_bit(bit, boot_cpu_data.x86_capability)
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