Commit e060f6ed authored by Paul Burton's avatar Paul Burton Committed by Ralf Baechle
Browse files

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: default avatarDoug Gilmore <doug.gilmore@imgtec.com>
Signed-off-by: default avatarPaul 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: default avatarRalf Baechle <ralf@linux-mips.org>
parent 651ca7f4

arch/mips/include/asm/maar.h

+9 −0
Original line number Diff line number Diff line
@@ -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

arch/mips/kernel/smp.c

+2 −0
Original line number Diff line number Diff line
@@ -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

arch/mips/mm/init.c

+25 −3
Original line number Diff line number Diff line
@@ -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);



	/* 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++;

		}

	}

}

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