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Use resume_cpus() instead of restart_cpus() to resume from ACPI suspension.

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restart_cpus() worked well enough by accident.  Before this set of fixes,
resume_cpus() used the same cpuset (started_cpus, meaning CPUs directed to
restart) as restart_cpus().  resume_cpus() waited for the wrong cpuset
(stopped_cpus) to become empty, but since mixtures of stopped and suspended
CPUs are not close to working, stopped_cpus must be empty when resuming so
the wait is null -- restart_cpus just allows the other CPUs to restart and
returns without waiting.

Fix resume_cpus() to wait on a non-wrong cpuset for the ACPI case, and
add further kludges to try to keep it working for the XEN case.  It
was only used for XEN.  It waited on suspended_cpus.  This works for
XEN.  However, for ACPI, resuming is a 2-step process.  ACPI has already
woken up the other CPUs and removed them from suspended_cpus.  This
fix records the move by putting them in a new cpuset resuming_cpus.
Waiting on suspended_cpus would give the same null wait as waiting on
stopped_cpus.  Wait on resuming_cpus instead.

Add a cpuset toresume_cpus to map the CPUs being told to resume to keep
this separate from the cpuset started_cpus for mapping the CPUs being told
to restart.  Mixtures of stopped and suspended/resuming CPUs are still far
from working.  Describe new and some old cpusets in comments.

Add further kludges to cpususpend_handler() to try to avoid breaking it
for XEN.  XEN doesn't use resumectx(), so it doesn't use the second
return path for savectx(), and it goes from the suspended state directly
to the restarted state, while ACPI resume goes through the resuming state.
Enter the resuming state early for all cases so that resume_cpus can test
for being in this state and not have to worry about the intermediate
!suspended state for ACPI only.

Reviewed by:	kib
This commit is contained in:
bde 2017-12-21 09:17:48 +00:00
parent fa3e727156
commit cf8a25e82e
4 changed files with 30 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
sys/kern/subr_smp.c
View File

@ -351,13 +351,18 @@ generic_restart_cpus(cpuset_t map, u_int type)
#if X86
if (type == IPI_SUSPEND)
cpus = &suspended_cpus;
cpus = &resuming_cpus;
else
#endif
cpus = &stopped_cpus;
/* signal other cpus to restart */
CPU_COPY_STORE_REL(&map, &started_cpus);
#if X86
if (type == IPI_SUSPEND)
CPU_COPY_STORE_REL(&map, &toresume_cpus);
else
#endif
CPU_COPY_STORE_REL(&map, &started_cpus);
#if X86
if (!nmi_is_broadcast || nmi_kdb_lock == 0) {

11
sys/sys/smp.h
View File

@ -155,10 +155,13 @@ struct cpu_group *smp_topo_find(struct cpu_group *top, int cpu);
extern void (*cpustop_restartfunc)(void);
extern int smp_cpus;
extern volatile cpuset_t started_cpus;
extern volatile cpuset_t stopped_cpus;
extern volatile cpuset_t suspended_cpus;
extern cpuset_t hlt_cpus_mask;
/* The suspend/resume cpusets are x86 only, but minimize ifdefs. */
extern volatile cpuset_t resuming_cpus; /* woken up cpus in suspend pen */
extern volatile cpuset_t started_cpus; /* cpus to let out of stop pen */
extern volatile cpuset_t stopped_cpus; /* cpus in stop pen */
extern volatile cpuset_t suspended_cpus; /* cpus [near] sleeping in susp pen */
extern volatile cpuset_t toresume_cpus; /* cpus to let out of suspend pen */
extern cpuset_t hlt_cpus_mask; /* XXX 'mask' is detail in old impl */
extern cpuset_t logical_cpus_mask;
#endif /* SMP */

2
sys/x86/acpica/acpi_wakeup.c
View File

@ -310,7 +310,7 @@ acpi_wakeup_machdep(struct acpi_softc *sc, int state, int sleep_result,
#ifdef SMP
if (!CPU_EMPTY(&suspcpus))
restart_cpus(suspcpus);
resume_cpus(suspcpus);
#endif
mca_resume();
#ifdef __amd64__

19
sys/x86/x86/mp_x86.c
View File

@ -124,6 +124,9 @@ struct cpu_ops cpu_ops;
static volatile cpuset_t ipi_stop_nmi_pending;
volatile cpuset_t resuming_cpus;
volatile cpuset_t toresume_cpus;
/* used to hold the AP's until we are ready to release them */
struct mtx ap_boot_mtx;
@ -1379,6 +1382,13 @@ cpususpend_handler(void)
#endif
wbinvd();
CPU_SET_ATOMIC(cpu, &suspended_cpus);
/*
* Hack for xen, which does not use resumectx() so never
* uses the next clause: set resuming_cpus early so that
* resume_cpus() can wait on the same bitmap for acpi and
* xen. resuming_cpus now means eventually_resumable_cpus.
*/
CPU_SET_ATOMIC(cpu, &resuming_cpus);
} else {
#ifdef __amd64__
fpuresume(susppcbs[cpu]->sp_fpususpend);
@ -1390,12 +1400,12 @@ cpususpend_handler(void)
PCPU_SET(switchtime, 0);
PCPU_SET(switchticks, ticks);
/* Indicate that we are resumed */
/* Indicate that we are resuming */
CPU_CLR_ATOMIC(cpu, &suspended_cpus);
}
/* Wait for resume */
while (!CPU_ISSET(cpu, &started_cpus))
/* Wait for resume directive */
while (!CPU_ISSET(cpu, &toresume_cpus))
ia32_pause();
#ifdef __i386__
@ -1416,8 +1426,9 @@ cpususpend_handler(void)
lapic_setup(0);
/* Indicate that we are resumed */
CPU_CLR_ATOMIC(cpu, &resuming_cpus);
CPU_CLR_ATOMIC(cpu, &suspended_cpus);
CPU_CLR_ATOMIC(cpu, &started_cpus);
CPU_CLR_ATOMIC(cpu, &toresume_cpus);
}