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x86/cacheinfo: Properly parse CPUID(0x80000005) L1d/L1i associativity

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For the AMD CPUID(4) emulation cache info logic, the same associativity
mapping array, assocs[], is used for both CPUID(0x80000005) and
CPUID(0x80000006).

This is incorrect since per the AMD manuals, the mappings for
CPUID(0x80000005) L1d/L1i associativity is:

   n = 0x1 -> 0xfe	n
   n = 0xff		fully associative

while assocs[] maps these values to:

   n = 0x1, 0x2, 0x4	n
   n = 0x3, 0x7, 0x9	0
   n = 0x6		8
   n = 0x8		16
   n = 0xa		32
   n = 0xb		48
   n = 0xc		64
   n = 0xd		96
   n = 0xe		128
   n = 0xf		fully associative

which is only valid for CPUID(0x80000006).

Parse CPUID(0x80000005) L1d/L1i associativity values as shown in the AMD
manuals.  Since the 0xffff literal is used to denote full associativity
at the AMD CPUID(4)-emulation logic, define AMD_CPUID4_FULLY_ASSOCIATIVE
for it instead of spreading that literal in more places.

Mark the assocs[] mapping array as only valid for CPUID(0x80000006) L2/L3
cache information.

Fixes: a326e948c5 ("x86, cacheinfo: Fixup L3 cache information for AMD multi-node processors")
Signed-off-by: Ahmed S. Darwish <darwi@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: x86-cpuid@lists.linux.dev
Link: https://lore.kernel.org/r/20250409122233.1058601-2-darwi@linutronix.de
This commit is contained in:
Ahmed S. Darwish
2025-04-09 14:22:30 +02:00
committed by Ingo Molnar
parent e37aa1211f
commit d274cde0db
1 changed files with 6 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

9
arch/x86/kernel/cpu/cacheinfo.c
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@@ -91,6 +91,8 @@ static const enum cache_type cache_type_map[] = {
* AMD CPUs with TOPOEXT can just use CPUID(0x8000001d)
*/
#define AMD_CPUID4_FULLY_ASSOCIATIVE 0xffff
union l1_cache {
struct {
unsigned line_size :8;
@@ -122,6 +124,7 @@ union l3_cache {
unsigned int val;
};
/* L2/L3 associativity mapping */
static const unsigned short assocs[] = {
[1] = 1,
[2] = 2,
@@ -133,7 +136,7 @@ static const unsigned short assocs[] = {
[0xc] = 64,
[0xd] = 96,
[0xe] = 128,
[0xf] = 0xffff /* Fully associative */
[0xf] = AMD_CPUID4_FULLY_ASSOCIATIVE
};
static const unsigned char levels[] = { 1, 1, 2, 3 };
@@ -163,7 +166,7 @@ static void legacy_amd_cpuid4(int index, union _cpuid4_leaf_eax *eax,
if (!l1->val)
return;
assoc = assocs[l1->assoc];
assoc = (l1->assoc == 0xff) ? AMD_CPUID4_FULLY_ASSOCIATIVE : l1->assoc;
line_size = l1->line_size;
lines_per_tag = l1->lines_per_tag;
size_in_kb = l1->size_in_kb;
@@ -201,7 +204,7 @@ static void legacy_amd_cpuid4(int index, union _cpuid4_leaf_eax *eax,
eax->split.num_threads_sharing = 0;
eax->split.num_cores_on_die = topology_num_cores_per_package();
if (assoc == 0xffff)
if (assoc == AMD_CPUID4_FULLY_ASSOCIATIVE)
eax->split.is_fully_associative = 1;
ebx->split.coherency_line_size = line_size - 1;