[Xen-devel] [PATCH] x86: set ARAT feature flag for non-buggy AMD CPUs

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

This is the equivalent of a recent Linux change.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>

--- a/xen/arch/x86/cpu/amd.c
+++ b/xen/arch/x86/cpu/amd.c
@@ -474,6 +474,10 @@ static void __devinit init_amd(struct cp
        }
 #endif
 
+       /* As a rule processors have APIC timer running in deep C states */
+       if (c->x86 >= 0xf && !cpu_has_amd_erratum(c, AMD_ERRATUM_400))
+               set_bit(X86_FEATURE_ARAT, c->x86_capability);
+
        /* Prevent TSC drift in non single-processor, single-core platforms. */
        if ((smp_processor_id() == 1) && c1_ramping_may_cause_clock_drift(c))
                disable_c1_ramping();
--- a/xen/include/asm-x86/amd.h
+++ b/xen/include/asm-x86/amd.h
@@ -134,6 +134,10 @@
     AMD_OSVW_ERRATUM(3, AMD_MODEL_RANGE(0x10, 0x2, 0x1, 0xff, 0xf),    \
                        AMD_MODEL_RANGE(0x12, 0x0, 0x0, 0x1, 0x0))
 
+#define AMD_ERRATUM_400                                                 \
+    AMD_OSVW_ERRATUM(1, AMD_MODEL_RANGE(0xf, 0x41, 0x2, 0xff, 0xf),     \
+                        AMD_MODEL_RANGE(0x10, 0x2, 0x1, 0xff, 0xf))
+
 struct cpuinfo_x86;
 int cpu_has_amd_erratum(const struct cpuinfo_x86 *, int, ...);

Attachment: x86-AMD-ARAT.patch
Description: Text document

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