Until recently Intel CPUs didn't support using non-contiguous 1s in Cache Allocation Technology (CAT). Writing a bitmask with non-contiguous 1s to the resctrl schemata file would fail. Intel CPUs that support non-contiguous 1s can be identified through a CPUID leaf mentioned in the "Intel® 64 and IA-32 Architectures Software Developer’s Manual" document available at: https://www.intel.com/content/www/us/en/developer/articles/technical/intel-sdm.html Add kernel support for detecting if non-contiguous 1s in Cache Allocation Technology (CAT) are supported by the hardware. Also add a new resctrl FS file to output this information to the userspace. Keep the hardcoded value for Haswell CPUs only since they do not have CPUID enumeration support for Cache allocation. Unify variable names to match the "bitmask" convention rather than the "bitmap" one to ensure consistency. Since the selftests/resctrl files are going through many rewrites and cleanups the appropriate selftest is still a work in progress. For basic selftesting capabilities use the bash script attached below this paragraph. It checks whether various bitmasks written into resctrl FS generate output consistent with reported feature support. #!/bin/bash # must be run as root, depends on a recent cpuid tool (20230406 or later) # variables RESCTRL_INFO="/sys/fs/resctrl/info" L3_NON_CONT_VAL="${RESCTRL_INFO}/L3/sparse_masks" L2_NON_CONT_VAL="${RESCTRL_INFO}/L2/sparse_masks" L3_NON_CONT_CBM="${RESCTRL_INFO}/L3/cbm_mask" L2_NON_CONT_CBM="${RESCTRL_INFO}/L2/cbm_mask" L3_CPUID_CMD="cpuid -1 -l 0x10 -s 0x01" L2_CPUID_CMD="cpuid -1 -l 0x10 -s 0x02" PASSED_TESTS=0 L3_SUPPORT=0 L2_SUPPORT=0 TESTS=0 run_test() { # L2 or L3 CACHE_LEVEL=$1 CACHE_LEVEL_SUPPORT="${CACHE_LEVEL}_SUPPORT" echo "Checking ${RESCTRL_INFO}/${CACHE_LEVEL}..." if [[ -d "${RESCTRL_INFO}/${CACHE_LEVEL}" ]]; then eval "${CACHE_LEVEL_SUPPORT}=1" echo "${CACHE_LEVEL} CAT Feature is supported" else echo "${CACHE_LEVEL} CAT Feature is not supported" fi if [[ ${!CACHE_LEVEL_SUPPORT} -eq 1 ]]; then echo " --- Running tests for ${CACHE_LEVEL} CAT ---" # read sysfs entries # are non-contiguous cbm supported? (driver sysfs) eval "NON_CONT_VAL=${CACHE_LEVEL}_NON_CONT_VAL" eval "NON_CONT_FEAT=$( cat ${!NON_CONT_VAL} )" # are non-contiguous cbm supported? (cpuid) CACHE_CPUID_CMD="${CACHE_LEVEL}_CPUID_CMD" NONCONT_CPUID=$(${!CACHE_CPUID_CMD} | grep non-contiguous | grep true) NONCONT_CPUID_RET=$(( !$? )) # what is the mask size? eval "NON_CONT_CBM=${CACHE_LEVEL}_NON_CONT_CBM" MAX_MASK=$(( 16#$( cat ${!NON_CONT_CBM} ) )) # prepare contiguous and non-contiguous masks for tests BC_STRING="l(${MAX_MASK})/l(2)" MAX_MASK_BIT_COUNT=$(echo ${BC_STRING} | bc -l) MAX_MASK_BIT_COUNT=$(printf "%.0f" "$MAX_MASK_BIT_COUNT") BITSHIFT=$(( $MAX_MASK_BIT_COUNT/2 - ($MAX_MASK_BIT_COUNT/2 % 4) )) CONT_MASK=$(( $MAX_MASK >> $BITSHIFT )) NONCONT_MASK=$(( ~( $MAX_MASK & ( 15<<$BITSHIFT) ) )) NONCONT_MASK=$(( $NONCONT_MASK & $MAX_MASK )) # test if cpuid reported support matches the sysfs one echo " * Testing if CPUID matches ${CACHE_LEVEL}/sparse_masks..." TESTS=$((TESTS + 1)) if [[ $NONCONT_CPUID_RET -eq $NON_CONT_FEAT ]]; then PASSED_TESTS=$((PASSED_TESTS + 1)) echo "There is a match!" else echo "Error - no match!" fi # test by writing CBMs to the schemata printf " * Writing 0x%x mask to the schemata...\n" ${CONT_MASK} TESTS=$((TESTS + 1)) SCHEMATA=$(printf "${CACHE_LEVEL}:0=%x" $CONT_MASK) echo "$SCHEMATA" > /sys/fs/resctrl/schemata if [[ $? -eq 0 ]]; then PASSED_TESTS=$((PASSED_TESTS + 1)) echo "Contiguous ${CACHE_LEVEL} write correct!" else echo "Contiguous ${CACHE_LEVEL} write ERROR!" fi printf " * Writing 0x%x mask to the schemata...\n" ${NONCONT_MASK} TESTS=$((TESTS + 1)) SCHEMATA=$(printf "${CACHE_LEVEL}:0=%x" $NONCONT_MASK) echo "$SCHEMATA" > /sys/fs/resctrl/schemata if [[ (($? -eq 0) && ($NON_CONT_FEAT -eq 1)) || \ (($? -ne 0) && ($NON_CONT_FEAT -eq 0)) ]]; then PASSED_TESTS=$((PASSED_TESTS + 1)) echo "Non-contiguous ${CACHE_LEVEL} write correct!" else echo "Non-contiguous ${CACHE_LEVEL} write ERROR!" fi fi } # mount resctrl mount -t resctrl resctrl /sys/fs/resctrl run_test L3 run_test L2 echo "TESTS PASSED / ALL TESTS : ${PASSED_TESTS} / ${TESTS}" # unmount resctrl umount /sys/fs/resctrl The series is based on tip/master branch. Changelog v5: - Rephrase patch messages (patches 1/4 and 2/4) according to Borislav's comments on Babu's [1] series. - Remove redundant message paragraph from patch 4/4. - Rebase onto tip/master. - Add Babu's reviewed-by tags. Changelog v4: - Add Ilpo's reviewed-by tags. - Add Reinette's reviewed-by tags. - Reorder tags in alignment with maintainer-tip.rst. Changelog v3: - Add Peter's tested-by and reviewed-by tags. - Change patch order to make 4th one the 1st. - Add error checking to schema_len variable. - Update cover letter since now the feature has moved from the SDM. Changelog v2: - Change git signature from Wieczor-Retman Maciej to Maciej Wieczor-Retman. - Change bitmap naming convention to bit mask. - Add patch to change arch_has_sparce_bitmaps name to match bitmask naming convention. [1] https://lore.kernel.org/all/20231003235430.1231238-1-babu.moger@xxxxxxx/ Fenghua Yu (2): x86/resctrl: Add sparse_masks file in info Documentation/x86: Document resctrl's new sparse_masks Maciej Wieczor-Retman (2): x86/resctrl: Rename arch_has_sparse_bitmaps x86/resctrl: Enable non-contiguous CBMs in Intel CAT Documentation/arch/x86/resctrl.rst | 16 ++++++++++++---- arch/x86/kernel/cpu/resctrl/core.c | 11 +++++++---- arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 14 ++++++++------ arch/x86/kernel/cpu/resctrl/internal.h | 9 +++++++++ arch/x86/kernel/cpu/resctrl/rdtgroup.c | 18 ++++++++++++++++++ include/linux/resctrl.h | 4 ++-- 6 files changed, 56 insertions(+), 16 deletions(-) base-commit: ef19bc9dddc3727dec1efa08683f658b1f4b7b78 -- 2.42.0
