[tip: x86/urgent] x86/resctrl: Fix min_cbm_bits for AMD

tip-bot2 for Babu Moger
2022-10-18T18:33:34Z

The following commit has been merged into the x86/urgent branch of tip:

Commit-ID: 67bf6493449b09590f9f71d7df29efb392b12d25
Gitweb: https://git.kernel.org/tip/67bf6493449b09590f9f71d7df29efb392b12d25
Author: Babu Moger <babu.moger@amd.com>
AuthorDate: Tue, 27 Sep 2022 15:16:29 -05:00
Committer: Borislav Petkov <bp@suse.de>
CommitterDate: Tue, 18 Oct 2022 20:25:16 +02:00

x86/resctrl: Fix min_cbm_bits for AMD

AMD systems support zero CBM (capacity bit mask) for cache allocation.
That is reflected in rdt_init_res_defs_amd() by:

r->cache.arch_has_empty_bitmaps = true;

However given the unified code in cbm_validate(), checking for:

val == 0 && !arch_has_empty_bitmaps

is not enough because of another check in cbm_validate():

if ((zero_bit - first_bit) < r->cache.min_cbm_bits)

The default value of r->cache.min_cbm_bits = 1.

Leading to:

$ cd /sys/fs/resctrl
$ mkdir foo
$ cd foo
$ echo L3:0=0 > schemata
-bash: echo: write error: Invalid argument
$ cat /sys/fs/resctrl/info/last_cmd_status
Need at least 1 bits in the mask

Initialize the min_cbm_bits to 0 for AMD. Also, remove the default
setting of min_cbm_bits and initialize it separately.

After the fix:

$ cd /sys/fs/resctrl
$ mkdir foo
$ cd foo
$ echo L3:0=0 > schemata
$ cat /sys/fs/resctrl/info/last_cmd_status
ok

Fixes: 316e7f901f5a ("x86/resctrl: Add struct rdt_cache::arch_has_{sparse, empty}_bitmaps")
Co-developed-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Babu Moger <babu.moger@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: James Morse <james.morse@arm.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Fenghua Yu <fenghua.yu@intel.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/lkml/20220517001234.3137157-1-eranian@google.com
---
arch/x86/kernel/cpu/resctrl/core.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index de62b0b..3266ea3 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -66,9 +66,6 @@ struct rdt_hw_resource rdt_resources_all[] = {
.rid = RDT_RESOURCE_L3,
.name = "L3",
.cache_level = 3,
- .cache = {
- .min_cbm_bits = 1,
- },
.domains = domain_init(RDT_RESOURCE_L3),
.parse_ctrlval = parse_cbm,
.format_str = "%d=%0*x",
@@ -83,9 +80,6 @@ struct rdt_hw_resource rdt_resources_all[] = {
.rid = RDT_RESOURCE_L2,
.name = "L2",
.cache_level = 2,
- .cache = {
- .min_cbm_bits = 1,
- },
.domains = domain_init(RDT_RESOURCE_L2),
.parse_ctrlval = parse_cbm,
.format_str = "%d=%0*x",
@@ -836,6 +830,7 @@ static __init void rdt_init_res_defs_intel(void)
r->cache.arch_has_sparse_bitmaps = false;
r->cache.arch_has_empty_bitmaps = false;
r->cache.arch_has_per_cpu_cfg = false;
+ r->cache.min_cbm_bits = 1;
} else if (r->rid == RDT_RESOURCE_MBA) {
hw_res->msr_base = MSR_IA32_MBA_THRTL_BASE;
hw_res->msr_update = mba_wrmsr_intel;
@@ -856,6 +851,7 @@ static __init void rdt_init_res_defs_amd(void)
r->cache.arch_has_sparse_bitmaps = true;
r->cache.arch_has_empty_bitmaps = true;
r->cache.arch_has_per_cpu_cfg = true;
+ r->cache.min_cbm_bits = 0;
} else if (r->rid == RDT_RESOURCE_MBA) {
hw_res->msr_base = MSR_IA32_MBA_BW_BASE;
hw_res->msr_update = mba_wrmsr_amd;