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://lore.kernel.org/lkml/20220517001234.3137157-1-eranian@xxxxxxxxxx/ > 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? Reinette
