[PATCH v2 23/45] arm_mpam: resctrl: Add rmid index helpers
From: Ben Horgan <ben.horgan@arm.com>
Date: 2025-12-19 18:13:53
Also in:
kvmarm, lkml
Subsystem:
mpam driver, the rest · Maintainers:
James Morse, Ben Horgan, Linus Torvalds
From: James Morse <james.morse@arm.com> Because MPAM's pmg aren't identical to RDT's rmid, resctrl handles some data structures by index. This allows x86 to map indexes to RMID, and MPAM to map them to partid-and-pmg. Add the helpers to do this. Signed-off-by: James Morse <james.morse@arm.com> Signed-off-by: Ben Horgan <ben.horgan@arm.com> --- Changes since rfc: Use ~0U instead of ~0 in lhs of left shift --- drivers/resctrl/mpam_resctrl.c | 28 ++++++++++++++++++++++++++++ include/linux/arm_mpam.h | 3 +++ 2 files changed, 31 insertions(+)
diff --git a/drivers/resctrl/mpam_resctrl.c b/drivers/resctrl/mpam_resctrl.c
index 4275b1a85887..bdbc5504964b 100644
--- a/drivers/resctrl/mpam_resctrl.c
+++ b/drivers/resctrl/mpam_resctrl.c@@ -120,6 +120,34 @@ u32 resctrl_arch_get_num_closid(struct rdt_resource *ignored) return mpam_partid_max + 1; } +u32 resctrl_arch_system_num_rmid_idx(void) +{ + u8 closid_shift = fls(mpam_pmg_max); + u32 num_partid = resctrl_arch_get_num_closid(NULL); + + return num_partid << closid_shift; +} + +u32 resctrl_arch_rmid_idx_encode(u32 closid, u32 rmid) +{ + u8 closid_shift = fls(mpam_pmg_max); + + WARN_ON_ONCE(closid_shift > 8); + + return (closid << closid_shift) | rmid; +} + +void resctrl_arch_rmid_idx_decode(u32 idx, u32 *closid, u32 *rmid) +{ + u8 closid_shift = fls(mpam_pmg_max); + u32 pmg_mask = ~(~0U << closid_shift); + + WARN_ON_ONCE(closid_shift > 8); + + *closid = idx >> closid_shift; + *rmid = idx & pmg_mask; +} + void resctrl_arch_sched_in(struct task_struct *tsk) { lockdep_assert_preemption_disabled();
diff --git a/include/linux/arm_mpam.h b/include/linux/arm_mpam.h
index ba0312b55d9f..385554ceb452 100644
--- a/include/linux/arm_mpam.h
+++ b/include/linux/arm_mpam.h@@ -59,6 +59,9 @@ void resctrl_arch_set_cpu_default_closid_rmid(int cpu, u32 closid, u32 rmid); void resctrl_arch_sched_in(struct task_struct *tsk); bool resctrl_arch_match_closid(struct task_struct *tsk, u32 closid); bool resctrl_arch_match_rmid(struct task_struct *tsk, u32 closid, u32 rmid); +u32 resctrl_arch_rmid_idx_encode(u32 closid, u32 rmid); +void resctrl_arch_rmid_idx_decode(u32 idx, u32 *closid, u32 *rmid); +u32 resctrl_arch_system_num_rmid_idx(void); /** * mpam_register_requestor() - Register a requestor with the MPAM driver
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2.43.0