[Xen-devel] [RFC 1/8] x86/timing: Command line parameter to disable ARAT

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

---
 xen/arch/x86/cpu/amd.c    |    2 +-
 xen/arch/x86/cpu/common.c |    3 +++
 xen/arch/x86/cpu/cpu.h    |    2 ++
 xen/arch/x86/cpu/intel.c  |    5 +++--
 4 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/xen/arch/x86/cpu/amd.c b/xen/arch/x86/cpu/amd.c
index 27b7f71..8d86d98 100644
--- a/xen/arch/x86/cpu/amd.c
+++ b/xen/arch/x86/cpu/amd.c
@@ -502,7 +502,7 @@ static void __devinit init_amd(struct cpuinfo_x86 *c)
         * Family 0x12 and above processors have APIC timer
         * running in deep C states.
         */
-       if (c->x86 > 0x11)
+       if ( opt_arat && c->x86 > 0x11)
                set_bit(X86_FEATURE_ARAT, c->x86_capability);
 
        /*
diff --git a/xen/arch/x86/cpu/common.c b/xen/arch/x86/cpu/common.c
index e1220e6..7e829b2 100644
--- a/xen/arch/x86/cpu/common.c
+++ b/xen/arch/x86/cpu/common.c
@@ -18,6 +18,9 @@
 static bool_t __cpuinitdata use_xsave = 1;
 boolean_param("xsave", use_xsave);
 
+bool_t __cpuinitdata opt_arat = 1;
+boolean_param("arat", opt_arat);
+
 unsigned int __devinitdata opt_cpuid_mask_ecx = ~0u;
 integer_param("cpuid_mask_ecx", opt_cpuid_mask_ecx);
 unsigned int __devinitdata opt_cpuid_mask_edx = ~0u;
diff --git a/xen/arch/x86/cpu/cpu.h b/xen/arch/x86/cpu/cpu.h
index 72c41ca..dde4d3a 100644
--- a/xen/arch/x86/cpu/cpu.h
+++ b/xen/arch/x86/cpu/cpu.h
@@ -15,6 +15,8 @@ extern unsigned int opt_cpuid_mask_ecx, opt_cpuid_mask_edx;
 extern unsigned int opt_cpuid_mask_xsave_eax;
 extern unsigned int opt_cpuid_mask_ext_ecx, opt_cpuid_mask_ext_edx;
 
+extern bool_t opt_arat;
+
 extern int get_model_name(struct cpuinfo_x86 *c);
 extern void display_cacheinfo(struct cpuinfo_x86 *c);
 
diff --git a/xen/arch/x86/cpu/intel.c b/xen/arch/x86/cpu/intel.c
index 31b69c9..fa0851b 100644
--- a/xen/arch/x86/cpu/intel.c
+++ b/xen/arch/x86/cpu/intel.c
@@ -226,8 +226,9 @@ static void __devinit init_intel(struct cpuinfo_x86 *c)
                set_bit(X86_FEATURE_NONSTOP_TSC, c->x86_capability);
                set_bit(X86_FEATURE_TSC_RELIABLE, c->x86_capability);
        }
-       if ((c->cpuid_level >= 0x00000006) &&
-           (cpuid_eax(0x00000006) & (1u<<2)))
+       if ( opt_arat &&
+            (c->cpuid_level >= 0x00000006) &&
+            (cpuid_eax(0x00000006) & (1u<<2)))
                set_bit(X86_FEATURE_ARAT, c->x86_capability);
 }
 
-- 
1.7.10.4


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