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Commit dbcf929c authored by David Gibson's avatar David Gibson Committed by Michael Ellerman
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powerpc/pseries: Add support for hash table resizing 



This adds support for using two hypercalls to change the size of the
main hash page table while running as a PAPR guest. For now these
hypercalls are only in experimental qemu versions.

The interface is two part: first H_RESIZE_HPT_PREPARE is used to
allocate and prepare the new hash table. This may be slow, but can be
done asynchronously. Then, H_RESIZE_HPT_COMMIT is used to switch to the
new hash table. This requires that no CPUs be concurrently updating the
HPT, and so must be run under stop_machine().

This also adds a debugfs file which can be used to manually control
HPT resizing or testing purposes.

Signed-off-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
Reviewed-by: default avatarPaul Mackerras <paulus@samba.org>
[mpe: Rename the debugfs file to "hpt_order"]
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 64b40ffb

arch/powerpc/include/asm/book3s/64/mmu-hash.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -157,6 +157,7 @@ struct mmu_hash_ops { 
					       unsigned long addr,

					       unsigned long addr,

					       unsigned char *hpte_slot_array,

					       unsigned char *hpte_slot_array,

					       int psize, int ssize, int local);

					       int psize, int ssize, int local);

	int		(*resize_hpt)(unsigned long shift);

	/*

	/*

	 * Special for kexec.

	 * Special for kexec.

	 * To be called in real mode with interrupts disabled. No locks are

	 * To be called in real mode with interrupts disabled. No locks are

arch/powerpc/mm/hash_utils_64.c

+33 −0
Original line number Original line Diff line number Diff line
@@ -35,7 +35,9 @@ 
#include <linux/memblock.h>

#include <linux/memblock.h>

#include <linux/context_tracking.h>

#include <linux/context_tracking.h>

#include <linux/libfdt.h>

#include <linux/libfdt.h>

#include <linux/debugfs.h>





#include <asm/debug.h>

#include <asm/processor.h>

#include <asm/processor.h>

#include <asm/pgtable.h>

#include <asm/pgtable.h>

#include <asm/mmu.h>

#include <asm/mmu.h>
@@ -1795,3 +1797,34 @@ void hash__setup_initial_memory_limit(phys_addr_t first_memblock_base, 
	/* Finally limit subsequent allocations */

	/* Finally limit subsequent allocations */

	memblock_set_current_limit(ppc64_rma_size);

	memblock_set_current_limit(ppc64_rma_size);

}

}



#ifdef CONFIG_DEBUG_FS



static int hpt_order_get(void *data, u64 *val)

{

	*val = ppc64_pft_size;

	return 0;

}



static int hpt_order_set(void *data, u64 val)

{

	if (!mmu_hash_ops.resize_hpt)

		return -ENODEV;



	return mmu_hash_ops.resize_hpt(val);

}



DEFINE_SIMPLE_ATTRIBUTE(fops_hpt_order, hpt_order_get, hpt_order_set, "%llu\n");



static int __init hash64_debugfs(void)

{

	if (!debugfs_create_file("hpt_order", 0600, powerpc_debugfs_root,

				 NULL, &fops_hpt_order)) {

		pr_err("lpar: unable to create hpt_order debugsfs file\n");

	}



	return 0;

}

machine_device_initcall(pseries, hash64_debugfs);



#endif /* CONFIG_DEBUG_FS */

arch/powerpc/platforms/pseries/lpar.c

+109 −0
Original line number Original line Diff line number Diff line
@@ -27,6 +27,8 @@ 
#include <linux/console.h>

#include <linux/console.h>

#include <linux/export.h>

#include <linux/export.h>

#include <linux/jump_label.h>

#include <linux/jump_label.h>

#include <linux/delay.h>

#include <linux/stop_machine.h>

#include <asm/processor.h>

#include <asm/processor.h>

#include <asm/mmu.h>

#include <asm/mmu.h>

#include <asm/page.h>

#include <asm/page.h>
@@ -609,6 +611,112 @@ static int __init disable_bulk_remove(char *str) 




__setup("bulk_remove=", disable_bulk_remove);

__setup("bulk_remove=", disable_bulk_remove);





#define HPT_RESIZE_TIMEOUT	10000 /* ms */



struct hpt_resize_state {

	unsigned long shift;

	int commit_rc;

};



static int pseries_lpar_resize_hpt_commit(void *data)

{

	struct hpt_resize_state *state = data;



	state->commit_rc = plpar_resize_hpt_commit(0, state->shift);

	if (state->commit_rc != H_SUCCESS)

		return -EIO;



	/* Hypervisor has transitioned the HTAB, update our globals */

	ppc64_pft_size = state->shift;

	htab_size_bytes = 1UL << ppc64_pft_size;

	htab_hash_mask = (htab_size_bytes >> 7) - 1;



	return 0;

}



/* Must be called in user context */

static int pseries_lpar_resize_hpt(unsigned long shift)

{

	struct hpt_resize_state state = {

		.shift = shift,

		.commit_rc = H_FUNCTION,

	};

	unsigned int delay, total_delay = 0;

	int rc;

	ktime_t t0, t1, t2;



	might_sleep();



	if (!firmware_has_feature(FW_FEATURE_HPT_RESIZE))

		return -ENODEV;



	printk(KERN_INFO "lpar: Attempting to resize HPT to shift %lu\n",

	       shift);



	t0 = ktime_get();



	rc = plpar_resize_hpt_prepare(0, shift);

	while (H_IS_LONG_BUSY(rc)) {

		delay = get_longbusy_msecs(rc);

		total_delay += delay;

		if (total_delay > HPT_RESIZE_TIMEOUT) {

			/* prepare with shift==0 cancels an in-progress resize */

			rc = plpar_resize_hpt_prepare(0, 0);

			if (rc != H_SUCCESS)

				printk(KERN_WARNING

				       "lpar: Unexpected error %d cancelling timed out HPT resize\n",

				       rc);

			return -ETIMEDOUT;

		}

		msleep(delay);

		rc = plpar_resize_hpt_prepare(0, shift);

	};



	switch (rc) {

	case H_SUCCESS:

		/* Continue on */

		break;



	case H_PARAMETER:

		return -EINVAL;

	case H_RESOURCE:

		return -EPERM;

	default:

		printk(KERN_WARNING

		       "lpar: Unexpected error %d from H_RESIZE_HPT_PREPARE\n",

		       rc);

		return -EIO;

	}



	t1 = ktime_get();



	rc = stop_machine(pseries_lpar_resize_hpt_commit, &state, NULL);



	t2 = ktime_get();



	if (rc != 0) {

		switch (state.commit_rc) {

		case H_PTEG_FULL:

			printk(KERN_WARNING

			       "lpar: Hash collision while resizing HPT\n");

			return -ENOSPC;



		default:

			printk(KERN_WARNING

			       "lpar: Unexpected error %d from H_RESIZE_HPT_COMMIT\n",

			       state.commit_rc);

			return -EIO;

		};

	}



	printk(KERN_INFO

	       "lpar: HPT resize to shift %lu complete (%lld ms / %lld ms)\n",

	       shift, (long long) ktime_ms_delta(t1, t0),

	       (long long) ktime_ms_delta(t2, t1));



	return 0;

}



void __init hpte_init_pseries(void)

void __init hpte_init_pseries(void)

{

{

	mmu_hash_ops.hpte_invalidate	 = pSeries_lpar_hpte_invalidate;

	mmu_hash_ops.hpte_invalidate	 = pSeries_lpar_hpte_invalidate;
@@ -620,6 +728,7 @@ void __init hpte_init_pseries(void) 
	mmu_hash_ops.flush_hash_range	 = pSeries_lpar_flush_hash_range;

	mmu_hash_ops.flush_hash_range	 = pSeries_lpar_flush_hash_range;

	mmu_hash_ops.hpte_clear_all      = pseries_hpte_clear_all;

	mmu_hash_ops.hpte_clear_all      = pseries_hpte_clear_all;

	mmu_hash_ops.hugepage_invalidate = pSeries_lpar_hugepage_invalidate;

	mmu_hash_ops.hugepage_invalidate = pSeries_lpar_hugepage_invalidate;

	mmu_hash_ops.resize_hpt		 = pseries_lpar_resize_hpt;

}

}





#ifdef CONFIG_PPC_SMLPAR

#ifdef CONFIG_PPC_SMLPAR