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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 <babu.moger@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://patch.msgid.link/9e9070100c320eab5368e088a3642443dee95ed7.1762995456.git.babu.moger@amd.com
This commit is contained in:
Babu Moger 2025-11-12 18:57:30 -06:00 committed by Borislav Petkov (AMD)
parent 7923ae7698
commit 556d2892aa
3 changed files with 66 additions and 0 deletions
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40
arch/x86/kernel/cpu/resctrl/ctrlmondata.c
View File

@ -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;
}

5
arch/x86/kernel/cpu/resctrl/internal.h
View File

@ -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)

21
include/linux/resctrl.h
View File

@ -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;