Hi Reinette, On 6/17/25 22:51, Reinette Chatre wrote: > Hi Babu, > > On 6/11/25 2:23 PM, Babu Moger wrote: >> "io_alloc" enables direct insertion of data from I/O devices into the L3 >> cache. > > Above is from resctrl perspective and resctrl does not limit this to L3. Here also > I think L3 should be dropped. Sure. > >> >> On AMD, "io_alloc" feature is backed by L3 Smart Data Cache Injection >> Allocation Enforcement (SDCIAE). Change SDCIAE state by setting (to enable) >> or clearing (to disable) bit 1 of MSR L3_QOS_EXT_CFG on all logical >> processors within the cache domain. >> >> Introduce architecture-specific handlers to enable and disable the feature. >> >> The SDCIAE feature details are available in APM listed below [1]. >> [1] AMD64 Architecture Programmer's Manual Volume 2: System Programming >> Publication # 24593 Revision 3.41 section 19.4.7 L3 Smart Data Cache >> Injection Allocation Enforcement (SDCIAE) >> >> Link: https://bugzilla.kernel.org/show_bug.cgi?id=206537 >> Signed-off-by: Babu Moger <babu.moger@xxxxxxx> >> --- > > ... > >> --- >> arch/x86/include/asm/msr-index.h | 1 + >> arch/x86/kernel/cpu/resctrl/internal.h | 5 ++++ >> arch/x86/kernel/cpu/resctrl/rdtgroup.c | 40 ++++++++++++++++++++++++++ >> include/linux/resctrl.h | 21 ++++++++++++++ > > This hints the subject prefix should be "x86,fs/resctrl". Sure. > >> 4 files changed, 67 insertions(+) >> >> diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h >> index b7dded3c8113..b92b04fa9888 100644 >> --- a/arch/x86/include/asm/msr-index.h >> +++ b/arch/x86/include/asm/msr-index.h >> @@ -1215,6 +1215,7 @@ >> /* - AMD: */ >> #define MSR_IA32_MBA_BW_BASE 0xc0000200 >> #define MSR_IA32_SMBA_BW_BASE 0xc0000280 >> +#define MSR_IA32_L3_QOS_EXT_CFG 0xc00003ff >> #define MSR_IA32_EVT_CFG_BASE 0xc0000400 >> >> /* AMD-V MSRs */ >> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h >> index 5e3c41b36437..cfa519ea2875 100644 >> --- a/arch/x86/kernel/cpu/resctrl/internal.h >> +++ b/arch/x86/kernel/cpu/resctrl/internal.h >> @@ -37,6 +37,9 @@ struct arch_mbm_state { >> u64 prev_msr; >> }; >> >> +/* Setting bit 1 in L3_QOS_EXT_CFG enables the SDCIAE feature. */ >> +#define SDCIAE_ENABLE_BIT 1 >> + >> /** >> * struct rdt_hw_ctrl_domain - Arch private attributes of a set of CPUs that share >> * a resource for a control function >> @@ -102,6 +105,7 @@ struct msr_param { >> * @mon_scale: cqm counter * mon_scale = occupancy in bytes >> * @mbm_width: Monitor width, to detect and correct for overflow. >> * @cdp_enabled: CDP state of this resource >> + * @sdciae_enabled: SDCIAE feature is enabled > > nit: "SDCIAE feature (backing "io_alloc") is enabled" Sure. > >> * >> * Members of this structure are either private to the architecture >> * e.g. mbm_width, or accessed via helpers that provide abstraction. e.g. >> @@ -115,6 +119,7 @@ struct rdt_hw_resource { >> unsigned int mon_scale; >> unsigned int mbm_width; >> bool cdp_enabled; >> + bool sdciae_enabled; >> }; >> >> static inline struct rdt_hw_resource *resctrl_to_arch_res(struct rdt_resource *r) >> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c >> index 885026468440..3bdcd53b3ce3 100644 >> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c >> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c >> @@ -229,6 +229,46 @@ bool resctrl_arch_get_cdp_enabled(enum resctrl_res_level l) >> return rdt_resources_all[l].cdp_enabled; >> } >> >> +inline bool resctrl_arch_get_io_alloc_enabled(struct rdt_resource *r) > > As indicated by lkp the inline usage needs to be fixed. I am assuming that you are referring to https://www.kernel.org/doc/html/next/process/coding-style.html#the-inline-disease I will remove inline attribute. > >> +{ >> + return resctrl_to_arch_res(r)->sdciae_enabled; >> +} >> + >> +static void resctrl_sdciae_set_one_amd(void *arg) >> +{ >> + bool *enable = arg; >> + >> + if (*enable) >> + msr_set_bit(MSR_IA32_L3_QOS_EXT_CFG, SDCIAE_ENABLE_BIT); >> + else >> + msr_clear_bit(MSR_IA32_L3_QOS_EXT_CFG, SDCIAE_ENABLE_BIT); >> +} >> + >> +static void _resctrl_sdciae_enable(struct rdt_resource *r, bool enable) >> +{ >> + struct rdt_ctrl_domain *d; >> + >> + /* Walking r->ctrl_domains, ensure it can't race with cpuhp */ >> + lockdep_assert_cpus_held(); >> + >> + /* Update L3_QOS_EXT_CFG MSR on all the CPUs in all domains */ >> + list_for_each_entry(d, &r->ctrl_domains, hdr.list) >> + on_each_cpu_mask(&d->hdr.cpu_mask, resctrl_sdciae_set_one_amd, &enable, 1); >> +} >> + >> +int resctrl_arch_io_alloc_enable(struct rdt_resource *r, bool enable) >> +{ >> + struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r); >> + >> + if (hw_res->r_resctrl.cache.io_alloc_capable && >> + hw_res->sdciae_enabled != enable) { >> + _resctrl_sdciae_enable(r, enable); >> + hw_res->sdciae_enabled = enable; >> + } >> + >> + return 0; >> +} >> + >> void resctrl_arch_reset_all_ctrls(struct rdt_resource *r) >> { >> struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r); >> diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h >> index 0e8641e41100..06e8a1821702 100644 >> --- a/include/linux/resctrl.h >> +++ b/include/linux/resctrl.h >> @@ -531,6 +531,27 @@ void resctrl_arch_reset_rmid_all(struct rdt_resource *r, struct rdt_mon_domain * >> */ >> void resctrl_arch_reset_all_ctrls(struct rdt_resource *r); >> >> +/** >> + * resctrl_arch_io_alloc_enable() - Enable/disable io_alloc feature. >> + * @r: The resctrl resource. >> + * @enable: Enable (true) or disable (false) io_alloc on resource @r. >> + * >> + * This can be called from any CPU. >> + * >> + * Return: >> + * 0 on success, or non-zero on error. > > Please change to "0 on success, <0 on error" to make clear it needs to be > non-zero *and* negative to be considered error by resctrl fs. Sure. > >> + */ >> +int resctrl_arch_io_alloc_enable(struct rdt_resource *r, bool enable); >> + >> +/** >> + * resctrl_arch_get_io_alloc_enabled() - Get io_alloc feature state. >> + * @r: The resctrl resource. >> + * >> + * Return: >> + * true if io_alloc is enabled or false if disabled. >> + */ >> +inline bool resctrl_arch_get_io_alloc_enabled(struct rdt_resource *r); >> + >> extern unsigned int resctrl_rmid_realloc_threshold; >> extern unsigned int resctrl_rmid_realloc_limit; >> > > Reinette > -- Thanks Babu Moger
