From 7923ae7698cf9728501974d76d8ea712686281bc Mon Sep 17 00:00:00 2001 From: Babu Moger Date: Wed, 12 Nov 2025 18:57:29 -0600 Subject: x86,fs/resctrl: Detect io_alloc feature AMD's SDCIAE (SDCI Allocation Enforcement) PQE feature enables system software to control the portions of L3 cache used for direct insertion of data from I/O devices into the L3 cache. Introduce a generic resctrl cache resource property "io_alloc_capable" as the first part of the new "io_alloc" resctrl feature that will support AMD's SDCIAE. Any architecture can set a cache resource as "io_alloc_capable" if a portion of the cache can be allocated for I/O traffic. Set the "io_alloc_capable" property for the L3 cache resource on x86 (AMD) systems that support SDCIAE. Signed-off-by: Babu Moger Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Reinette Chatre Link: https://patch.msgid.link/df85a9a6081674fd3ef6b4170920485512ce2ded.1762995456.git.babu.moger@amd.com --- include/linux/resctrl.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include/linux') diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h index a7d92718b653..533f240dbe21 100644 --- a/include/linux/resctrl.h +++ b/include/linux/resctrl.h @@ -206,6 +206,8 @@ struct rdt_mon_domain { * @arch_has_sparse_bitmasks: True if a bitmask like f00f is valid. * @arch_has_per_cpu_cfg: True if QOS_CFG register for this cache * level has CPU scope. + * @io_alloc_capable: True if portion of the cache can be configured + * for I/O traffic. */ struct resctrl_cache { unsigned int cbm_len; @@ -213,6 +215,7 @@ struct resctrl_cache { unsigned int shareable_bits; bool arch_has_sparse_bitmasks; bool arch_has_per_cpu_cfg; + bool io_alloc_capable; }; /** -- cgit v1.2.3 From 556d2892aa715286d840a74216c8fff885559261 Mon Sep 17 00:00:00 2001 From: Babu Moger Date: Wed, 12 Nov 2025 18:57:30 -0600 Subject: x86,fs/resctrl: Implement "io_alloc" enable/disable handlers "io_alloc" is the generic name of the new resctrl feature that enables system software to configure the portion of cache allocated for I/O traffic. On AMD systems, "io_alloc" resctrl feature is backed by AMD's L3 Smart Data Cache Injection Allocation Enforcement (SDCIAE). Introduce the architecture-specific functions that resctrl fs should call to enable, disable, or check status of the "io_alloc" feature. Change SDCIAE state by setting (to enable) or clearing (to disable) bit 1 of MSR_IA32_L3_QOS_EXT_CFG on all logical processors within the cache domain. Signed-off-by: Babu Moger Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Reinette Chatre Link: https://patch.msgid.link/9e9070100c320eab5368e088a3642443dee95ed7.1762995456.git.babu.moger@amd.com --- arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 40 +++++++++++++++++++++++++++++++ arch/x86/kernel/cpu/resctrl/internal.h | 5 ++++ include/linux/resctrl.h | 21 ++++++++++++++++ 3 files changed, 66 insertions(+) (limited to 'include/linux') diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c index 1189c0df4ad7..b20e705606b8 100644 --- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c +++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c @@ -91,3 +91,43 @@ u32 resctrl_arch_get_config(struct rdt_resource *r, struct rdt_ctrl_domain *d, return hw_dom->ctrl_val[idx]; } + +bool resctrl_arch_get_io_alloc_enabled(struct rdt_resource *r) +{ + 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 MSR_IA32_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; +} diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h index 9f4c2f0aaf5c..4a916c84a322 100644 --- a/arch/x86/kernel/cpu/resctrl/internal.h +++ b/arch/x86/kernel/cpu/resctrl/internal.h @@ -46,6 +46,9 @@ struct arch_mbm_state { #define ABMC_EXTENDED_EVT_ID BIT(31) #define ABMC_EVT_ID BIT(0) +/* Setting bit 1 in MSR_IA32_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 @@ -112,6 +115,7 @@ struct msr_param { * @mbm_width: Monitor width, to detect and correct for overflow. * @cdp_enabled: CDP state of this resource * @mbm_cntr_assign_enabled: ABMC feature is enabled + * @sdciae_enabled: SDCIAE feature (backing "io_alloc") is enabled. * * Members of this structure are either private to the architecture * e.g. mbm_width, or accessed via helpers that provide abstraction. e.g. @@ -126,6 +130,7 @@ struct rdt_hw_resource { unsigned int mbm_width; bool cdp_enabled; bool mbm_cntr_assign_enabled; + bool sdciae_enabled; }; static inline struct rdt_hw_resource *resctrl_to_arch_res(struct rdt_resource *r) diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h index 533f240dbe21..54701668b3df 100644 --- a/include/linux/resctrl.h +++ b/include/linux/resctrl.h @@ -657,6 +657,27 @@ void resctrl_arch_reset_cntr(struct rdt_resource *r, struct rdt_mon_domain *d, u32 closid, u32 rmid, int cntr_id, enum resctrl_event_id eventid); +/** + * 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, <0 on error. + */ +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. + */ +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; -- cgit v1.2.3