[Xen-devel] [PATCH 2/3] xen/x86: Query for paddr_bits in early_cpu_detect()

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

It is __read_mostly, so repeatedly writing to it is suboptiomal.  As the
MTRRs have already been set up, nothing good will come from its value
changing across CPUs.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
---
 xen/arch/x86/cpu/common.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/cpu/common.c b/xen/arch/x86/cpu/common.c
index 02f2504..ac8a258 100644
--- a/xen/arch/x86/cpu/common.c
+++ b/xen/arch/x86/cpu/common.c
@@ -207,6 +207,9 @@ static void __init early_cpu_detect(void)
        /* Leaf 0x1 capabilities filled in early for Xen. */
        c->x86_capability[cpufeat_word(X86_FEATURE_FPU)] = cap0;
        c->x86_capability[cpufeat_word(X86_FEATURE_XMM3)] = cap4;
+
+       if ( cpuid_eax(0x80000000) >= 0x80000008 )
+               paddr_bits = cpuid_eax(0x80000008) & 0xff;
 }
 
 static void __cpuinit generic_identify(struct cpuinfo_x86 *c)
@@ -254,8 +257,6 @@ static void __cpuinit generic_identify(struct cpuinfo_x86 
*c)
                }
                if ( c->extended_cpuid_level >= 0x80000004 )
                        get_model_name(c); /* Default name */
-               if ( c->extended_cpuid_level >= 0x80000008 )
-                       paddr_bits = cpuid_eax(0x80000008) & 0xff;
        }
 
        /* Might lift BIOS max_leaf=3 limit. */
-- 
2.1.4


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