On 8/23/22 15:56, Reinette Chatre wrote: > Hi Babu, > > On 8/22/2022 6:42 AM, Babu Moger wrote: >> AMD systems support zero CBM (capacity bit mask) for L3 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 >> >> Fix the issue by initializing 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 >> >> Link: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Flkml%2F20220517001234.3137157-1-eranian%40google.com%2F&data=05%7C01%7Cbabu.moger%40amd.com%7Cd695c39eb7d94d659db008da8549ed74%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637968849807214070%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=prSwl8bTHx0y3o9hBNxp3u%2FNu8SrNcEWUwDOCQCVURk%3D&reserved=0 >> Fixes: 316e7f901f5a ("x86/resctrl: Add struct rdt_cache::arch_has_{sparse, empty}_bitmaps") >> Signed-off-by: Stephane Eranian <eranian@xxxxxxxxxx> >> Signed-off-by: Babu Moger <babu.moger@xxxxxxx> >> Reviewed-by: Ingo Molnar <mingo@xxxxxxxxxx> >> --- >> 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 bb1c3f5f60c8..a5c51a14fbce 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", >> @@ -877,6 +871,7 @@ 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; >> @@ -897,6 +892,7 @@ 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; >> >> > Thank you for putting this together. > > This change makes arch_has_empty_bitmaps redundant. Can it be removed? Hi Reinette, Actually, I thought about that. Sure. We can remove it. -- Thanks Babu Moger
