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MIPS: Initialise MAARs on secondary CPUs 

MAARs should be initialised on each CPU (or rather, core) in the system
in order to achieve consistent behaviour & performance. Previously they
have only been initialised on the boot CPU which leads to performance
problems if tasks are later scheduled on a secondary CPU, particularly
if those tasks make use of unaligned vector accesses where some CPUs
don't handle any cases in hardware for non-speculative memory regions.
Fix this by recording the MAAR configuration from the boot CPU and
applying it to secondary CPUs as part of their bringup.

Reported-by: Doug Gilmore <doug.gilmore@imgtec.com>
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Steven J. Hill <Steven.Hill@imgtec.com>
Cc: Andrew Bresticker <abrestic@chromium.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: David Hildenbrand <dahi@linux.vnet.ibm.com>
Cc: linux-kernel@vger.kernel.org
Cc: Aaro Koskinen <aaro.koskinen@iki.fi>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Cc: Hemmo Nieminen <hemmo.nieminen@iki.fi>
Cc: Alex Smith <alex.smith@imgtec.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Patchwork: https://patchwork.linux-mips.org/patch/11239/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Paul Burton 2015-09-25 08:59:38 -07:00 committed by Ralf Baechle
parent 651ca7f4da
commit e060f6ed28
3 changed files with 36 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
arch/mips/include/asm/maar.h
View File

@ -65,6 +65,15 @@ static inline void write_maar_pair(unsigned idx, phys_addr_t lower,
back_to_back_c0_hazard();
}
/**
* maar_init() - initialise MAARs
*
* Performs initialisation of MAARs for the current CPU, making use of the
* platforms implementation of platform_maar_init where necessary and
* duplicating the setup it provides on secondary CPUs.
*/
extern void maar_init(void);
/**
* struct maar_config - MAAR configuration data
* @lower: The lowest address that the MAAR pair will affect. Must be

2
arch/mips/kernel/smp.c
View File

@ -42,6 +42,7 @@
#include <asm/mmu_context.h>
#include <asm/time.h>
#include <asm/setup.h>
#include <asm/maar.h>
cpumask_t cpu_callin_map; /* Bitmask of started secondaries */
@ -157,6 +158,7 @@ asmlinkage void start_secondary(void)
mips_clockevent_init();
mp_ops->init_secondary();
cpu_report();
maar_init();
/*
* XXX parity protection should be folded in here when it's converted

28
arch/mips/mm/init.c
View File

@ -44,6 +44,7 @@
#include <asm/pgalloc.h>
#include <asm/tlb.h>
#include <asm/fixmap.h>
#include <asm/maar.h>
/*
* We have up to 8 empty zeroed pages so we can map one of the right colour
@ -288,10 +289,14 @@ unsigned __weak platform_maar_init(unsigned num_pairs)
return num_configured;
}
static void maar_init(void)
void maar_init(void)
{
unsigned num_maars, used, i;
phys_addr_t lower, upper, attr;
static struct {
struct maar_config cfgs[3];
unsigned used;
} recorded = { { { 0 } }, 0 };
if (!cpu_has_maar)
return;
@ -304,8 +309,14 @@ static void maar_init(void)
/* MAARs should be in pairs */
WARN_ON(num_maars % 2);
/* Configure the required MAARs */
used = platform_maar_init(num_maars / 2);
/* Set MAARs using values we recorded already */
if (recorded.used) {
used = maar_config(recorded.cfgs, recorded.used, num_maars / 2);
BUG_ON(used != recorded.used);
} else {
/* Configure the required MAARs */
used = platform_maar_init(num_maars / 2);
}
/* Disable any further MAARs */
for (i = (used * 2); i < num_maars; i++) {
@ -315,6 +326,9 @@ static void maar_init(void)
back_to_back_c0_hazard();
}
if (recorded.used)
return;
pr_info("MAAR configuration:\n");
for (i = 0; i < num_maars; i += 2) {
write_c0_maari(i);
@ -341,6 +355,14 @@ static void maar_init(void)
pr_cont(" speculate");
pr_cont("\n");
/* Record the setup for use on secondary CPUs */
if (used <= ARRAY_SIZE(recorded.cfgs)) {
recorded.cfgs[recorded.used].lower = lower;
recorded.cfgs[recorded.used].upper = upper;
recorded.cfgs[recorded.used].attrs = attr;
recorded.used++;
}
}
}