Commit 5246adec authored by Anton Blanchard's avatar Anton Blanchard Committed by Michael Ellerman
Browse files

powerpc/pseries: Use H_CLEAR_HPT to clear MMU hash table during kexec 



An hcall was recently added that does exactly what we need during kexec
- it clears the entire MMU hash table, ignoring any VRMA mappings.

Try it and fall back to the old method if we get a failure.

On a POWER8 box with 5TB of memory, this reduces the time it takes to
kexec a new kernel from from 4 minutes to 1 minute.

Signed-off-by: default avatarAnton Blanchard <anton@samba.org>
Tested-by: default avatarMahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
[mpe: Split into separate functions and tweak function naming]
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 9e607f72

arch/powerpc/include/asm/hvcall.h

+2 −1
Original line number Diff line number Diff line
@@ -275,7 +275,8 @@ 
#define H_COP			0x304

#define H_GET_MPP_X		0x314

#define H_SET_MODE		0x31C

#define MAX_HCALL_OPCODE	H_SET_MODE

#define H_CLEAR_HPT		0x358

#define MAX_HCALL_OPCODE	H_CLEAR_HPT



/* H_VIOCTL functions */

#define H_GET_VIOA_DUMP_SIZE	0x01

arch/powerpc/platforms/pseries/lpar.c

+22 −2
Original line number Diff line number Diff line
@@ -221,7 +221,7 @@ static long pSeries_lpar_hpte_remove(unsigned long hpte_group) 
	return -1;

}



static void pSeries_lpar_hptab_clear(void)

static void manual_hpte_clear_all(void)

{

	unsigned long size_bytes = 1UL << ppc64_pft_size;

	unsigned long hpte_count = size_bytes >> 4;
@@ -249,6 +249,26 @@ static void pSeries_lpar_hptab_clear(void) 
					&(ptes[j].pteh), &(ptes[j].ptel));

		}

	}

}



static int hcall_hpte_clear_all(void)

{

	int rc;



	do {

		rc = plpar_hcall_norets(H_CLEAR_HPT);

	} while (rc == H_CONTINUE);



	return rc;

}



static void pseries_hpte_clear_all(void)

{

	int rc;



	rc = hcall_hpte_clear_all();

	if (rc != H_SUCCESS)

		manual_hpte_clear_all();



#ifdef __LITTLE_ENDIAN__

	/*
@@ -598,7 +618,7 @@ void __init hpte_init_pseries(void) 
	mmu_hash_ops.hpte_remove	 = pSeries_lpar_hpte_remove;

	mmu_hash_ops.hpte_removebolted   = pSeries_lpar_hpte_removebolted;

	mmu_hash_ops.flush_hash_range	 = pSeries_lpar_flush_hash_range;

	mmu_hash_ops.hpte_clear_all      = pSeries_lpar_hptab_clear;

	mmu_hash_ops.hpte_clear_all      = pseries_hpte_clear_all;

	mmu_hash_ops.hugepage_invalidate = pSeries_lpar_hugepage_invalidate;

}