[PATCH] x86/AMD: also determine L3 cache size

[Jan Beulich <jbeulich@xxxxxxxx>]

For Intel CPUs we record L3 cache size, hence we should also do so for
AMD and alike.

While making these additions, also make sure (throughout the function)
that we don't needlessly overwrite prior values when the new value to be
stored is zero.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
I have to admit though that I'm not convinced the sole real use of the
field (in flush_area_local()) is a good one - flushing an entire L3's
worth of lines via CLFLUSH may not be more efficient than using WBINVD.
But I didn't measure it (yet).

--- a/xen/arch/x86/cpu/common.c
+++ b/xen/arch/x86/cpu/common.c
@@ -240,28 +240,41 @@ int get_model_name(struct cpuinfo_x86 *c
 
 void display_cacheinfo(struct cpuinfo_x86 *c)
 {
-       unsigned int dummy, ecx, edx, l2size;
+       unsigned int dummy, ecx, edx, size;
 
        if (c->extended_cpuid_level >= 0x80000005) {
                cpuid(0x80000005, &dummy, &dummy, &ecx, &edx);
-               if (opt_cpu_info)
-                       printk("CPU: L1 I cache %dK (%d bytes/line),"
-                                     " D cache %dK (%d bytes/line)\n",
-                              edx>>24, edx&0xFF, ecx>>24, ecx&0xFF);
-               c->x86_cache_size=(ecx>>24)+(edx>>24);  
+               if ((edx | ecx) >> 24) {
+                       if (opt_cpu_info)
+                               printk("CPU: L1 I cache %uK (%u bytes/line),"
+                                             " D cache %uK (%u bytes/line)\n",
+                                      edx >> 24, edx & 0xFF, ecx >> 24, ecx & 
0xFF);
+                       c->x86_cache_size = (ecx >> 24) + (edx >> 24);
+               }
        }
 
        if (c->extended_cpuid_level < 0x80000006)       /* Some chips just has 
a large L1. */
                return;
 
-       ecx = cpuid_ecx(0x80000006);
-       l2size = ecx >> 16;
-       
-       c->x86_cache_size = l2size;
-
-       if (opt_cpu_info)
-               printk("CPU: L2 Cache: %dK (%d bytes/line)\n",
-                      l2size, ecx & 0xFF);
+       cpuid(0x80000006, &dummy, &dummy, &ecx, &edx);
+
+       size = ecx >> 16;
+       if (size) {
+               c->x86_cache_size = size;
+
+               if (opt_cpu_info)
+                       printk("CPU: L2 Cache: %uK (%u bytes/line)\n",
+                              size, ecx & 0xFF);
+       }
+
+       size = edx >> 18;
+       if (size) {
+               c->x86_cache_size = size * 512;
+
+               if (opt_cpu_info)
+                       printk("CPU: L3 Cache: %uM (%u bytes/line)\n",
+                              (size + (size & 1)) >> 1, edx & 0xFF);
+       }
 }
 
 static inline u32 _phys_pkg_id(u32 cpuid_apic, int index_msb)