Hi Babu, On 9/24/2018 12:19 PM, Moger, Babu wrote: > +/* > + * Check whether a cache bit mask is valid. AMD allows > + * non-contiguous masks. > + */ > +bool cbm_validate_amd(char *buf, u32 *data, struct rdt_resource *r) > +{ > + unsigned long first_bit, zero_bit, val; > + unsigned int cbm_len = r->cache.cbm_len; > + int ret; > + > + ret = kstrtoul(buf, 16, &val); > + if (ret) { > + rdt_last_cmd_printf("non-hex character in mask %s\n", buf); > + return false; > + } > + > + if (val == 0 || val > r->default_ctrl) { > + rdt_last_cmd_puts("mask out of range\n"); > + return false; > + }
According to https://www.amd.com/system/files/TechDocs/56375_Quality_of_Service_Extensions.pdf "If an L3_MASK_n register is programmed with all 0’s, that COS will be prevented from allocating any lines in the L3 cache." The "val == 0" test thus does not seem necessary. > + > + first_bit = find_first_bit(&val, cbm_len); > + zero_bit = find_next_zero_bit(&val, cbm_len, first_bit); > + > + > + if ((zero_bit - first_bit) < r->cache.min_cbm_bits) { > + rdt_last_cmd_printf("Need at least %d bits in mask\n", > + r->cache.min_cbm_bits); > + return false; > + } If AMD platforms accept CBM of all zeroes then it seems that the platforms would not require a minimum number of set bits? Reinette