[Xen-devel] [PATCH][RFC] Remove CPUID4 emulation for AMD CPUs

[Wei Huang <wei.huang2@xxxxxxx>]

The CPUID4 emulation code for AMD CPUs in intel_cacheinfo.c won't be executed. 
This emulation code was from upstream kernel, where CPUID4 is used for cache 
information report in sysfs. But in Xen, this code path won't be executed on 
AMD CPUs. init_amd() uses display_cacheinfo() to find out CPU cache size 
instead.

Signed-off-by: Wei Huang <wei.huang2@xxxxxxx>
Acked-by: Mark Langsdorf <mark.langsdorf@xxxxxxx>



diff -r efa1b905d893 xen/arch/x86/cpu/intel_cacheinfo.c
--- a/xen/arch/x86/cpu/intel_cacheinfo.c        Tue May 04 13:59:55 2010 +0100
+++ b/xen/arch/x86/cpu/intel_cacheinfo.c        Wed May 05 23:37:54 2010 -0500
@@ -129,122 +129,6 @@
 
 unsigned short                 num_cache_leaves;
 
-/* AMD doesn't have CPUID4. Emulate it here to report the same
-   information to the user.  This makes some assumptions about the machine:
-   L2 not shared, no SMT etc. that is currently true on AMD CPUs.
-
-   In theory the TLBs could be reported as fake type (they are in "dummy").
-   Maybe later */
-union l1_cache {
-       struct {
-               unsigned line_size : 8;
-               unsigned lines_per_tag : 8;
-               unsigned assoc : 8;
-               unsigned size_in_kb : 8;
-       };
-       unsigned val;
-};
-
-union l2_cache {
-       struct {
-               unsigned line_size : 8;
-               unsigned lines_per_tag : 4;
-               unsigned assoc : 4;
-               unsigned size_in_kb : 16;
-       };
-       unsigned val;
-};
-
-union l3_cache {
-       struct {
-               unsigned line_size : 8;
-               unsigned lines_per_tag : 4;
-               unsigned assoc : 4;
-               unsigned res : 2;
-               unsigned size_encoded : 14;
-       };
-       unsigned val;
-};
-
-static const unsigned short assocs[] = {
-       [1] = 1, [2] = 2, [4] = 4, [6] = 8,
-       [8] = 16, [0xa] = 32, [0xb] = 48,
-       [0xc] = 64,
-       [0xf] = 0xffff // ??
-};
-
-static const unsigned char levels[] = { 1, 1, 2, 3 };
-static const unsigned char types[] = { 1, 2, 3, 3 };
-
-static void __cpuinit amd_cpuid4(int leaf, union _cpuid4_leaf_eax *eax,
-                      union _cpuid4_leaf_ebx *ebx,
-                      union _cpuid4_leaf_ecx *ecx)
-{
-       unsigned dummy;
-       unsigned line_size, lines_per_tag, assoc, size_in_kb;
-       union l1_cache l1i, l1d;
-       union l2_cache l2;
-       union l3_cache l3;
-       union l1_cache *l1 = &l1d;
-
-       eax->full = 0;
-       ebx->full = 0;
-       ecx->full = 0;
-
-       cpuid(0x80000005, &dummy, &dummy, &l1d.val, &l1i.val);
-       cpuid(0x80000006, &dummy, &dummy, &l2.val, &l3.val);
-
-       switch (leaf) {
-       case 1:
-               l1 = &l1i;
-       case 0:
-               if (!l1->val)
-                       return;
-               assoc = l1->assoc;
-               line_size = l1->line_size;
-               lines_per_tag = l1->lines_per_tag;
-               size_in_kb = l1->size_in_kb;
-               break;
-       case 2:
-               if (!l2.val)
-                       return;
-               assoc = l2.assoc;
-               line_size = l2.line_size;
-               lines_per_tag = l2.lines_per_tag;
-               /* cpu_data has errata corrections for K7 applied */
-               size_in_kb = current_cpu_data.x86_cache_size;
-               break;
-       case 3:
-               if (!l3.val)
-                       return;
-               assoc = l3.assoc;
-               line_size = l3.line_size;
-               lines_per_tag = l3.lines_per_tag;
-               size_in_kb = l3.size_encoded * 512;
-               break;
-       default:
-               return;
-       }
-
-       eax->split.is_self_initializing = 1;
-       eax->split.type = types[leaf];
-       eax->split.level = levels[leaf];
-       if (leaf == 3)
-               eax->split.num_threads_sharing = current_cpu_data.x86_max_cores 
- 1;
-       else
-               eax->split.num_threads_sharing = 0;
-       eax->split.num_cores_on_die = current_cpu_data.x86_max_cores - 1;
-
-
-       if (assoc == 0xf)
-               eax->split.is_fully_associative = 1;
-       ebx->split.coherency_line_size = line_size - 1;
-       ebx->split.ways_of_associativity = assocs[assoc] - 1;
-       ebx->split.physical_line_partition = lines_per_tag - 1;
-       ecx->split.number_of_sets = (size_in_kb * 1024) / line_size /
-               (ebx->split.ways_of_associativity + 1) - 1;
-}
-
 static int __cpuinit cpuid4_cache_lookup(int index, struct _cpuid4_info 
*this_leaf)
 {
        union _cpuid4_leaf_eax  eax;
@@ -252,10 +136,7 @@
        union _cpuid4_leaf_ecx  ecx;
        unsigned                edx;
 
-       if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
-               amd_cpuid4(index, &eax, &ebx, &ecx);
-       else
-               cpuid_count(4, index, &eax.full, &ebx.full, &ecx.full,  &edx);
+        cpuid_count(4, index, &eax.full, &ebx.full, &ecx.full,  &edx);
        if (eax.split.type == CACHE_TYPE_NULL)
                return -EIO; /* better error ? */
 

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