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9d6792ffe1
The drmem lmb list can have hundreds of thousands of entries, and
unfortunately lookups take the form of linear searches. As long as
this is the case, traversals have the potential to monopolize the CPU
and provoke lockup reports, workqueue stalls, and the like unless
they explicitly yield.
Rather than placing cond_resched() calls within various
for_each_drmem_lmb() loop blocks in the code, put it in the iteration
expression of the loop macro itself so users can't omit it.
Introduce a drmem_lmb_next() iteration helper function which calls
cond_resched() at a regular interval during array traversal. Each
iteration of the loop in DLPAR code paths can involve around ten RTAS
calls which can each take up to 250us, so this ensures the check is
performed at worst every few milliseconds.
Fixes: 6c6ea53725 ("powerpc/mm: Separate ibm, dynamic-memory data from DT format")
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200813151131.2070161-1-nathanl@linux.ibm.com
143 lines
3.2 KiB
C
143 lines
3.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* drmem.h: Power specific logical memory block representation
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*
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* Copyright 2017 IBM Corporation
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*/
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#ifndef _ASM_POWERPC_LMB_H
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#define _ASM_POWERPC_LMB_H
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#include <linux/sched.h>
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struct drmem_lmb {
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u64 base_addr;
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u32 drc_index;
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u32 aa_index;
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u32 flags;
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#ifdef CONFIG_MEMORY_HOTPLUG
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int nid;
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#endif
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};
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struct drmem_lmb_info {
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struct drmem_lmb *lmbs;
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int n_lmbs;
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u32 lmb_size;
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};
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extern struct drmem_lmb_info *drmem_info;
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static inline struct drmem_lmb *drmem_lmb_next(struct drmem_lmb *lmb,
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const struct drmem_lmb *start)
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{
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/*
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* DLPAR code paths can take several milliseconds per element
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* when interacting with firmware. Ensure that we don't
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* unfairly monopolize the CPU.
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*/
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if (((++lmb - start) % 16) == 0)
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cond_resched();
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return lmb;
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}
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#define for_each_drmem_lmb_in_range(lmb, start, end) \
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for ((lmb) = (start); (lmb) < (end); lmb = drmem_lmb_next(lmb, start))
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#define for_each_drmem_lmb(lmb) \
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for_each_drmem_lmb_in_range((lmb), \
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&drmem_info->lmbs[0], \
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&drmem_info->lmbs[drmem_info->n_lmbs])
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/*
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* The of_drconf_cell_v1 struct defines the layout of the LMB data
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* specified in the ibm,dynamic-memory device tree property.
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* The property itself is a 32-bit value specifying the number of
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* LMBs followed by an array of of_drconf_cell_v1 entries, one
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* per LMB.
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*/
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struct of_drconf_cell_v1 {
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__be64 base_addr;
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__be32 drc_index;
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__be32 reserved;
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__be32 aa_index;
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__be32 flags;
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};
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/*
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* Version 2 of the ibm,dynamic-memory property is defined as a
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* 32-bit value specifying the number of LMB sets followed by an
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* array of of_drconf_cell_v2 entries, one per LMB set.
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*/
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struct of_drconf_cell_v2 {
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u32 seq_lmbs;
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u64 base_addr;
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u32 drc_index;
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u32 aa_index;
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u32 flags;
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} __packed;
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#define DRCONF_MEM_ASSIGNED 0x00000008
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#define DRCONF_MEM_AI_INVALID 0x00000040
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#define DRCONF_MEM_RESERVED 0x00000080
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#define DRCONF_MEM_HOTREMOVABLE 0x00000100
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static inline u32 drmem_lmb_size(void)
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{
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return drmem_info->lmb_size;
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}
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#define DRMEM_LMB_RESERVED 0x80000000
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static inline void drmem_mark_lmb_reserved(struct drmem_lmb *lmb)
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{
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lmb->flags |= DRMEM_LMB_RESERVED;
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}
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static inline void drmem_remove_lmb_reservation(struct drmem_lmb *lmb)
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{
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lmb->flags &= ~DRMEM_LMB_RESERVED;
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}
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static inline bool drmem_lmb_reserved(struct drmem_lmb *lmb)
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{
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return lmb->flags & DRMEM_LMB_RESERVED;
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}
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u64 drmem_lmb_memory_max(void);
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int walk_drmem_lmbs(struct device_node *dn, void *data,
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int (*func)(struct drmem_lmb *, const __be32 **, void *));
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int drmem_update_dt(void);
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#ifdef CONFIG_PPC_PSERIES
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int __init
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walk_drmem_lmbs_early(unsigned long node, void *data,
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int (*func)(struct drmem_lmb *, const __be32 **, void *));
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#endif
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static inline void invalidate_lmb_associativity_index(struct drmem_lmb *lmb)
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{
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lmb->aa_index = 0xffffffff;
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}
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#ifdef CONFIG_MEMORY_HOTPLUG
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static inline void lmb_set_nid(struct drmem_lmb *lmb)
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{
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lmb->nid = memory_add_physaddr_to_nid(lmb->base_addr);
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}
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static inline void lmb_clear_nid(struct drmem_lmb *lmb)
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{
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lmb->nid = -1;
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}
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#else
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static inline void lmb_set_nid(struct drmem_lmb *lmb)
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{
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}
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static inline void lmb_clear_nid(struct drmem_lmb *lmb)
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{
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}
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#endif
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#endif /* _ASM_POWERPC_LMB_H */
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