[v2][PATCH 2/5] x86/cpu: Expose only stepping min/max interface

From: Dave Hansen
Date: Fri Dec 13 2024 - 13:51:57 EST


From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>

The x86_match_cpu() infrastructure can match CPU steppings. Since
there are only 16 possible steppings, the matching infrastructure goes
all out and stores the stepping match as a bitmap. That means it can
match any possible steppings in a single list entry. Fun.

But it exposes this bitmap to each of the X86_MATCH_*() helpers when
none of them really need a bitmap. It makes up for this by exporting a
helper (X86_STEPPINGS()) which converts a contiguous stepping range
into the bitmap which every single user leverages.

Instead of a bitmap, have the main helper for this sort of thing
(X86_MATCH_VFM_STEPS()) just take a stepping range. This ends up
actually being even more compact than before.

Leave the helper in place (renamed to __X86_STEPPINGS()) to make it
more clear what is going on instead of just having a random GENMASK()
in the middle of an already complicated macro.

One oddity that I hit was this macro:

#define VULNBL_INTEL_STEPS(vfm, max_stepping, issues) \
X86_MATCH_VFM_STEPS(vfm, X86_STEPPING_MIN, max_stepping, issues)

It *could* have been converted over to take a min/max stepping value
for each entry. But that would have been a bit too verbose and would
prevent the one oddball in the list (INTEL_COMETLAKE_L stepping 0)
from sticking out.

Instead, just have it take a *maximum* stepping and imply that the match
is from 0=>max_stepping. This is functional for all the cases now and
also retains the nice property of having INTEL_COMETLAKE_L stepping 0
stick out like a sore thumb.

skx_cpuids[] is goofy. It uses the stepping match but encodes all
possible steppings. Just use a normal, non-stepping match helper.

Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Suggested-by: Ingo Molnar <mingo@xxxxxxxxxx>
---

b/arch/x86/include/asm/cpu_device_id.h | 15 +++---
b/arch/x86/kernel/apic/apic.c | 18 +++----
b/arch/x86/kernel/cpu/common.c | 78 ++++++++++++++++-----------------
b/drivers/edac/i10nm_base.c | 21 ++++----
b/drivers/edac/skx_base.c | 2
b/include/linux/mod_devicetable.h | 2
6 files changed, 70 insertions(+), 66 deletions(-)

diff -puN arch/x86/include/asm/cpu_device_id.h~zap-X86_STEPPINGS arch/x86/include/asm/cpu_device_id.h
--- a/arch/x86/include/asm/cpu_device_id.h~zap-X86_STEPPINGS 2024-12-13 10:47:38.281373050 -0800
+++ b/arch/x86/include/asm/cpu_device_id.h 2024-12-13 10:47:38.293373533 -0800
@@ -56,7 +56,6 @@
/* x86_cpu_id::flags */
#define X86_CPU_ID_FLAG_ENTRY_VALID BIT(0)

-#define X86_STEPPINGS(mins, maxs) GENMASK(maxs, mins)
/**
* X86_MATCH_VENDOR_FAM_MODEL_STEPPINGS_FEATURE - Base macro for CPU matching
* @_vendor: The vendor name, e.g. INTEL, AMD, HYGON, ..., ANY
@@ -208,6 +207,7 @@
VFM_MODEL(vfm), \
X86_STEPPING_ANY, X86_FEATURE_ANY, data)

+#define __X86_STEPPINGS(mins, maxs) GENMASK(maxs, mins)
/**
* X86_MATCH_VFM_STEPPINGS - Match encoded vendor/family/model/stepping
* @vfm: Encoded 8-bits each for vendor, family, model
@@ -218,12 +218,13 @@
*
* feature is set to wildcard
*/
-#define X86_MATCH_VFM_STEPPINGS(vfm, steppings, data) \
- X86_MATCH_VENDORID_FAM_MODEL_STEPPINGS_FEATURE( \
- VFM_VENDOR(vfm), \
- VFM_FAMILY(vfm), \
- VFM_MODEL(vfm), \
- steppings, X86_FEATURE_ANY, data)
+#define X86_MATCH_VFM_STEPS(vfm, min_step, max_step, data) \
+ X86_MATCH_VENDORID_FAM_MODEL_STEPPINGS_FEATURE( \
+ VFM_VENDOR(vfm), \
+ VFM_FAMILY(vfm), \
+ VFM_MODEL(vfm), \
+ __X86_STEPPINGS(min_step, max_step), \
+ X86_FEATURE_ANY, data)

/**
* X86_MATCH_VFM_FEATURE - Match encoded vendor/family/model/feature
diff -puN arch/x86/kernel/apic/apic.c~zap-X86_STEPPINGS arch/x86/kernel/apic/apic.c
--- a/arch/x86/kernel/apic/apic.c~zap-X86_STEPPINGS 2024-12-13 10:47:38.285373210 -0800
+++ b/arch/x86/kernel/apic/apic.c 2024-12-13 10:47:38.293373533 -0800
@@ -509,19 +509,19 @@ static struct clock_event_device lapic_c
static DEFINE_PER_CPU(struct clock_event_device, lapic_events);

static const struct x86_cpu_id deadline_match[] __initconst = {
- X86_MATCH_VFM_STEPPINGS(INTEL_HASWELL_X, X86_STEPPINGS(0x2, 0x2), 0x3a), /* EP */
- X86_MATCH_VFM_STEPPINGS(INTEL_HASWELL_X, X86_STEPPINGS(0x4, 0x4), 0x0f), /* EX */
+ X86_MATCH_VFM_STEPS(INTEL_HASWELL_X, 0x2, 0x2, 0x3a), /* EP */
+ X86_MATCH_VFM_STEPS(INTEL_HASWELL_X, 0x4, 0x4, 0x0f), /* EX */

X86_MATCH_VFM(INTEL_BROADWELL_X, 0x0b000020),

- X86_MATCH_VFM_STEPPINGS(INTEL_BROADWELL_D, X86_STEPPINGS(0x2, 0x2), 0x00000011),
- X86_MATCH_VFM_STEPPINGS(INTEL_BROADWELL_D, X86_STEPPINGS(0x3, 0x3), 0x0700000e),
- X86_MATCH_VFM_STEPPINGS(INTEL_BROADWELL_D, X86_STEPPINGS(0x4, 0x4), 0x0f00000c),
- X86_MATCH_VFM_STEPPINGS(INTEL_BROADWELL_D, X86_STEPPINGS(0x5, 0x5), 0x0e000003),
+ X86_MATCH_VFM_STEPS(INTEL_BROADWELL_D, 0x2, 0x2, 0x00000011),
+ X86_MATCH_VFM_STEPS(INTEL_BROADWELL_D, 0x3, 0x3, 0x0700000e),
+ X86_MATCH_VFM_STEPS(INTEL_BROADWELL_D, 0x4, 0x4, 0x0f00000c),
+ X86_MATCH_VFM_STEPS(INTEL_BROADWELL_D, 0x5, 0x5, 0x0e000003),

- X86_MATCH_VFM_STEPPINGS(INTEL_SKYLAKE_X, X86_STEPPINGS(0x3, 0x3), 0x01000136),
- X86_MATCH_VFM_STEPPINGS(INTEL_SKYLAKE_X, X86_STEPPINGS(0x4, 0x4), 0x02000014),
- X86_MATCH_VFM_STEPPINGS(INTEL_SKYLAKE_X, X86_STEPPINGS(0x5, 0xf), 0),
+ X86_MATCH_VFM_STEPS(INTEL_SKYLAKE_X, 0x3, 0x3, 0x01000136),
+ X86_MATCH_VFM_STEPS(INTEL_SKYLAKE_X, 0x4, 0x4, 0x02000014),
+ X86_MATCH_VFM_STEPS(INTEL_SKYLAKE_X, 0x5, 0xf, 0),

X86_MATCH_VFM(INTEL_HASWELL, 0x22),
X86_MATCH_VFM(INTEL_HASWELL_L, 0x20),
diff -puN arch/x86/kernel/cpu/common.c~zap-X86_STEPPINGS arch/x86/kernel/cpu/common.c
--- a/arch/x86/kernel/cpu/common.c~zap-X86_STEPPINGS 2024-12-13 10:47:38.285373210 -0800
+++ b/arch/x86/kernel/cpu/common.c 2024-12-13 10:47:38.293373533 -0800
@@ -1201,8 +1201,8 @@ static const __initconst struct x86_cpu_
#define VULNBL(vendor, family, model, blacklist) \
X86_MATCH_VENDOR_FAM_MODEL(vendor, family, model, blacklist)

-#define VULNBL_INTEL_STEPPINGS(vfm, steppings, issues) \
- X86_MATCH_VFM_STEPPINGS(vfm, steppings, issues)
+#define VULNBL_INTEL_STEPS(vfm, max_stepping, issues) \
+ X86_MATCH_VFM_STEPS(vfm, X86_STEP_MIN, max_stepping, issues)

#define VULNBL_AMD(family, blacklist) \
VULNBL(AMD, family, X86_MODEL_ANY, blacklist)
@@ -1227,43 +1227,43 @@ static const __initconst struct x86_cpu_
#define RFDS BIT(7)

static const struct x86_cpu_id cpu_vuln_blacklist[] __initconst = {
- VULNBL_INTEL_STEPPINGS(INTEL_IVYBRIDGE, X86_STEPPING_ANY, SRBDS),
- VULNBL_INTEL_STEPPINGS(INTEL_HASWELL, X86_STEPPING_ANY, SRBDS),
- VULNBL_INTEL_STEPPINGS(INTEL_HASWELL_L, X86_STEPPING_ANY, SRBDS),
- VULNBL_INTEL_STEPPINGS(INTEL_HASWELL_G, X86_STEPPING_ANY, SRBDS),
- VULNBL_INTEL_STEPPINGS(INTEL_HASWELL_X, X86_STEPPING_ANY, MMIO),
- VULNBL_INTEL_STEPPINGS(INTEL_BROADWELL_D, X86_STEPPING_ANY, MMIO),
- VULNBL_INTEL_STEPPINGS(INTEL_BROADWELL_G, X86_STEPPING_ANY, SRBDS),
- VULNBL_INTEL_STEPPINGS(INTEL_BROADWELL_X, X86_STEPPING_ANY, MMIO),
- VULNBL_INTEL_STEPPINGS(INTEL_BROADWELL, X86_STEPPING_ANY, SRBDS),
- VULNBL_INTEL_STEPPINGS(INTEL_SKYLAKE_X, X86_STEPPING_ANY, MMIO | RETBLEED | GDS),
- VULNBL_INTEL_STEPPINGS(INTEL_SKYLAKE_L, X86_STEPPING_ANY, MMIO | RETBLEED | GDS | SRBDS),
- VULNBL_INTEL_STEPPINGS(INTEL_SKYLAKE, X86_STEPPING_ANY, MMIO | RETBLEED | GDS | SRBDS),
- VULNBL_INTEL_STEPPINGS(INTEL_KABYLAKE_L, X86_STEPPING_ANY, MMIO | RETBLEED | GDS | SRBDS),
- VULNBL_INTEL_STEPPINGS(INTEL_KABYLAKE, X86_STEPPING_ANY, MMIO | RETBLEED | GDS | SRBDS),
- VULNBL_INTEL_STEPPINGS(INTEL_CANNONLAKE_L, X86_STEPPING_ANY, RETBLEED),
- VULNBL_INTEL_STEPPINGS(INTEL_ICELAKE_L, X86_STEPPING_ANY, MMIO | MMIO_SBDS | RETBLEED | GDS),
- VULNBL_INTEL_STEPPINGS(INTEL_ICELAKE_D, X86_STEPPING_ANY, MMIO | GDS),
- VULNBL_INTEL_STEPPINGS(INTEL_ICELAKE_X, X86_STEPPING_ANY, MMIO | GDS),
- VULNBL_INTEL_STEPPINGS(INTEL_COMETLAKE, X86_STEPPING_ANY, MMIO | MMIO_SBDS | RETBLEED | GDS),
- VULNBL_INTEL_STEPPINGS(INTEL_COMETLAKE_L, X86_STEPPINGS(0x0, 0x0), MMIO | RETBLEED),
- VULNBL_INTEL_STEPPINGS(INTEL_COMETLAKE_L, X86_STEPPING_ANY, MMIO | MMIO_SBDS | RETBLEED | GDS),
- VULNBL_INTEL_STEPPINGS(INTEL_TIGERLAKE_L, X86_STEPPING_ANY, GDS),
- VULNBL_INTEL_STEPPINGS(INTEL_TIGERLAKE, X86_STEPPING_ANY, GDS),
- VULNBL_INTEL_STEPPINGS(INTEL_LAKEFIELD, X86_STEPPING_ANY, MMIO | MMIO_SBDS | RETBLEED),
- VULNBL_INTEL_STEPPINGS(INTEL_ROCKETLAKE, X86_STEPPING_ANY, MMIO | RETBLEED | GDS),
- VULNBL_INTEL_STEPPINGS(INTEL_ALDERLAKE, X86_STEPPING_ANY, RFDS),
- VULNBL_INTEL_STEPPINGS(INTEL_ALDERLAKE_L, X86_STEPPING_ANY, RFDS),
- VULNBL_INTEL_STEPPINGS(INTEL_RAPTORLAKE, X86_STEPPING_ANY, RFDS),
- VULNBL_INTEL_STEPPINGS(INTEL_RAPTORLAKE_P, X86_STEPPING_ANY, RFDS),
- VULNBL_INTEL_STEPPINGS(INTEL_RAPTORLAKE_S, X86_STEPPING_ANY, RFDS),
- VULNBL_INTEL_STEPPINGS(INTEL_ATOM_GRACEMONT, X86_STEPPING_ANY, RFDS),
- VULNBL_INTEL_STEPPINGS(INTEL_ATOM_TREMONT, X86_STEPPING_ANY, MMIO | MMIO_SBDS | RFDS),
- VULNBL_INTEL_STEPPINGS(INTEL_ATOM_TREMONT_D, X86_STEPPING_ANY, MMIO | RFDS),
- VULNBL_INTEL_STEPPINGS(INTEL_ATOM_TREMONT_L, X86_STEPPING_ANY, MMIO | MMIO_SBDS | RFDS),
- VULNBL_INTEL_STEPPINGS(INTEL_ATOM_GOLDMONT, X86_STEPPING_ANY, RFDS),
- VULNBL_INTEL_STEPPINGS(INTEL_ATOM_GOLDMONT_D, X86_STEPPING_ANY, RFDS),
- VULNBL_INTEL_STEPPINGS(INTEL_ATOM_GOLDMONT_PLUS, X86_STEPPING_ANY, RFDS),
+ VULNBL_INTEL_STEPS(INTEL_IVYBRIDGE, X86_STEP_MAX, SRBDS),
+ VULNBL_INTEL_STEPS(INTEL_HASWELL, X86_STEP_MAX, SRBDS),
+ VULNBL_INTEL_STEPS(INTEL_HASWELL_L, X86_STEP_MAX, SRBDS),
+ VULNBL_INTEL_STEPS(INTEL_HASWELL_G, X86_STEP_MAX, SRBDS),
+ VULNBL_INTEL_STEPS(INTEL_HASWELL_X, X86_STEP_MAX, MMIO),
+ VULNBL_INTEL_STEPS(INTEL_BROADWELL_D, X86_STEP_MAX, MMIO),
+ VULNBL_INTEL_STEPS(INTEL_BROADWELL_G, X86_STEP_MAX, SRBDS),
+ VULNBL_INTEL_STEPS(INTEL_BROADWELL_X, X86_STEP_MAX, MMIO),
+ VULNBL_INTEL_STEPS(INTEL_BROADWELL, X86_STEP_MAX, SRBDS),
+ VULNBL_INTEL_STEPS(INTEL_SKYLAKE_X, X86_STEP_MAX, MMIO | RETBLEED | GDS),
+ VULNBL_INTEL_STEPS(INTEL_SKYLAKE_L, X86_STEP_MAX, MMIO | RETBLEED | GDS | SRBDS),
+ VULNBL_INTEL_STEPS(INTEL_SKYLAKE, X86_STEP_MAX, MMIO | RETBLEED | GDS | SRBDS),
+ VULNBL_INTEL_STEPS(INTEL_KABYLAKE_L, X86_STEP_MAX, MMIO | RETBLEED | GDS | SRBDS),
+ VULNBL_INTEL_STEPS(INTEL_KABYLAKE, X86_STEP_MAX, MMIO | RETBLEED | GDS | SRBDS),
+ VULNBL_INTEL_STEPS(INTEL_CANNONLAKE_L, X86_STEP_MAX, RETBLEED),
+ VULNBL_INTEL_STEPS(INTEL_ICELAKE_L, X86_STEP_MAX, MMIO | MMIO_SBDS | RETBLEED | GDS),
+ VULNBL_INTEL_STEPS(INTEL_ICELAKE_D, X86_STEP_MAX, MMIO | GDS),
+ VULNBL_INTEL_STEPS(INTEL_ICELAKE_X, X86_STEP_MAX, MMIO | GDS),
+ VULNBL_INTEL_STEPS(INTEL_COMETLAKE, X86_STEP_MAX, MMIO | MMIO_SBDS | RETBLEED | GDS),
+ VULNBL_INTEL_STEPS(INTEL_COMETLAKE_L, 0x0, MMIO | RETBLEED),
+ VULNBL_INTEL_STEPS(INTEL_COMETLAKE_L, X86_STEP_MAX, MMIO | MMIO_SBDS | RETBLEED | GDS),
+ VULNBL_INTEL_STEPS(INTEL_TIGERLAKE_L, X86_STEP_MAX, GDS),
+ VULNBL_INTEL_STEPS(INTEL_TIGERLAKE, X86_STEP_MAX, GDS),
+ VULNBL_INTEL_STEPS(INTEL_LAKEFIELD, X86_STEP_MAX, MMIO | MMIO_SBDS | RETBLEED),
+ VULNBL_INTEL_STEPS(INTEL_ROCKETLAKE, X86_STEP_MAX, MMIO | RETBLEED | GDS),
+ VULNBL_INTEL_STEPS(INTEL_ALDERLAKE, X86_STEP_MAX, RFDS),
+ VULNBL_INTEL_STEPS(INTEL_ALDERLAKE_L, X86_STEP_MAX, RFDS),
+ VULNBL_INTEL_STEPS(INTEL_RAPTORLAKE, X86_STEP_MAX, RFDS),
+ VULNBL_INTEL_STEPS(INTEL_RAPTORLAKE_P, X86_STEP_MAX, RFDS),
+ VULNBL_INTEL_STEPS(INTEL_RAPTORLAKE_S, X86_STEP_MAX, RFDS),
+ VULNBL_INTEL_STEPS(INTEL_ATOM_GRACEMONT, X86_STEP_MAX, RFDS),
+ VULNBL_INTEL_STEPS(INTEL_ATOM_TREMONT, X86_STEP_MAX, MMIO | MMIO_SBDS | RFDS),
+ VULNBL_INTEL_STEPS(INTEL_ATOM_TREMONT_D, X86_STEP_MAX, MMIO | RFDS),
+ VULNBL_INTEL_STEPS(INTEL_ATOM_TREMONT_L, X86_STEP_MAX, MMIO | MMIO_SBDS | RFDS),
+ VULNBL_INTEL_STEPS(INTEL_ATOM_GOLDMONT, X86_STEP_MAX, RFDS),
+ VULNBL_INTEL_STEPS(INTEL_ATOM_GOLDMONT_D, X86_STEP_MAX, RFDS),
+ VULNBL_INTEL_STEPS(INTEL_ATOM_GOLDMONT_PLUS, X86_STEP_MAX, RFDS),

VULNBL_AMD(0x15, RETBLEED),
VULNBL_AMD(0x16, RETBLEED),
diff -puN drivers/edac/i10nm_base.c~zap-X86_STEPPINGS drivers/edac/i10nm_base.c
--- a/drivers/edac/i10nm_base.c~zap-X86_STEPPINGS 2024-12-13 10:47:38.285373210 -0800
+++ b/drivers/edac/i10nm_base.c 2024-12-13 10:47:38.293373533 -0800
@@ -938,16 +938,17 @@ static struct res_config gnr_cfg = {
};

static const struct x86_cpu_id i10nm_cpuids[] = {
- X86_MATCH_VFM_STEPPINGS(INTEL_ATOM_TREMONT_D, X86_STEPPINGS(0x0, 0x3), &i10nm_cfg0),
- X86_MATCH_VFM_STEPPINGS(INTEL_ATOM_TREMONT_D, X86_STEPPINGS(0x4, 0xf), &i10nm_cfg1),
- X86_MATCH_VFM_STEPPINGS(INTEL_ICELAKE_X, X86_STEPPINGS(0x0, 0x3), &i10nm_cfg0),
- X86_MATCH_VFM_STEPPINGS(INTEL_ICELAKE_X, X86_STEPPINGS(0x4, 0xf), &i10nm_cfg1),
- X86_MATCH_VFM_STEPPINGS(INTEL_ICELAKE_D, X86_STEPPINGS(0x0, 0xf), &i10nm_cfg1),
- X86_MATCH_VFM_STEPPINGS(INTEL_SAPPHIRERAPIDS_X, X86_STEPPINGS(0x0, 0xf), &spr_cfg),
- X86_MATCH_VFM_STEPPINGS(INTEL_EMERALDRAPIDS_X, X86_STEPPINGS(0x0, 0xf), &spr_cfg),
- X86_MATCH_VFM_STEPPINGS(INTEL_GRANITERAPIDS_X, X86_STEPPINGS(0x0, 0xf), &gnr_cfg),
- X86_MATCH_VFM_STEPPINGS(INTEL_ATOM_CRESTMONT_X, X86_STEPPINGS(0x0, 0xf), &gnr_cfg),
- X86_MATCH_VFM_STEPPINGS(INTEL_ATOM_CRESTMONT, X86_STEPPINGS(0x0, 0xf), &gnr_cfg),
+ X86_MATCH_VFM_STEPS(INTEL_ATOM_TREMONT_D, X86_STEP_MIN, 0x3, &i10nm_cfg0),
+ X86_MATCH_VFM_STEPS(INTEL_ATOM_TREMONT_D, 0x4, X86_STEP_MAX, &i10nm_cfg1),
+ X86_MATCH_VFM_STEPS(INTEL_ICELAKE_X, X86_STEP_MIN, 0x3, &i10nm_cfg0),
+ X86_MATCH_VFM_STEPS(INTEL_ICELAKE_X, 0x4, X86_STEP_MAX, &i10nm_cfg1),
+ X86_MATCH_VFM( INTEL_ICELAKE_D, &i10nm_cfg1),
+
+ X86_MATCH_VFM(INTEL_SAPPHIRERAPIDS_X, &spr_cfg),
+ X86_MATCH_VFM(INTEL_EMERALDRAPIDS_X, &spr_cfg),
+ X86_MATCH_VFM(INTEL_GRANITERAPIDS_X, &gnr_cfg),
+ X86_MATCH_VFM(INTEL_ATOM_CRESTMONT_X, &gnr_cfg),
+ X86_MATCH_VFM(INTEL_ATOM_CRESTMONT, &gnr_cfg),
{}
};
MODULE_DEVICE_TABLE(x86cpu, i10nm_cpuids);
diff -puN drivers/edac/skx_base.c~zap-X86_STEPPINGS drivers/edac/skx_base.c
--- a/drivers/edac/skx_base.c~zap-X86_STEPPINGS 2024-12-13 10:47:38.289373371 -0800
+++ b/drivers/edac/skx_base.c 2024-12-13 10:47:38.293373533 -0800
@@ -164,7 +164,7 @@ static struct res_config skx_cfg = {
};

static const struct x86_cpu_id skx_cpuids[] = {
- X86_MATCH_VFM_STEPPINGS(INTEL_SKYLAKE_X, X86_STEPPINGS(0x0, 0xf), &skx_cfg),
+ X86_MATCH_VFM(INTEL_SKYLAKE_X, &skx_cfg),
{ }
};
MODULE_DEVICE_TABLE(x86cpu, skx_cpuids);
diff -puN include/linux/mod_devicetable.h~zap-X86_STEPPINGS include/linux/mod_devicetable.h
--- a/include/linux/mod_devicetable.h~zap-X86_STEPPINGS 2024-12-13 10:47:38.289373371 -0800
+++ b/include/linux/mod_devicetable.h 2024-12-13 10:47:38.293373533 -0800
@@ -700,6 +700,8 @@ struct x86_cpu_id {
#define X86_FAMILY_ANY 0
#define X86_MODEL_ANY 0
#define X86_STEPPING_ANY 0
+#define X86_STEP_MIN 0
+#define X86_STEP_MAX 0xf
#define X86_FEATURE_ANY 0 /* Same as FPU, you can't test for that */

/*
_