[PATCH -V7 09/10] powerpc: Optimize hugepage invalidate

David Gibson dwg at au1.ibm.com
Fri May 3 15:28:46 EST 2013


On Mon, Apr 29, 2013 at 01:21:50AM +0530, Aneesh Kumar K.V wrote:
> From: "Aneesh Kumar K.V" <aneesh.kumar at linux.vnet.ibm.com>
> 
> Hugepage invalidate involves invalidating multiple hpte entries.
> Optimize the operation using H_BULK_REMOVE on lpar platforms.
> On native, reduce the number of tlb flush.
> 
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar at linux.vnet.ibm.com>

Since this is purely an optimization, have you tried reproducing the
bugs you're chasing with this patch not included?

> ---
>  arch/powerpc/include/asm/machdep.h    |   3 +
>  arch/powerpc/mm/hash_native_64.c      |  78 +++++++++++++++++++++
>  arch/powerpc/mm/pgtable_64.c          |  13 +++-
>  arch/powerpc/platforms/pseries/lpar.c | 126 ++++++++++++++++++++++++++++++++--
>  4 files changed, 210 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/machdep.h b/arch/powerpc/include/asm/machdep.h
> index 3f3f691..5d1e7d2 100644
> --- a/arch/powerpc/include/asm/machdep.h
> +++ b/arch/powerpc/include/asm/machdep.h
> @@ -56,6 +56,9 @@ struct machdep_calls {
>  	void            (*hpte_removebolted)(unsigned long ea,
>  					     int psize, int ssize);
>  	void		(*flush_hash_range)(unsigned long number, int local);
> +	void		(*hugepage_invalidate)(struct mm_struct *mm,
> +					       unsigned char *hpte_slot_array,
> +					       unsigned long addr, int psize);
>  
>  	/* special for kexec, to be called in real mode, linear mapping is
>  	 * destroyed as well */
> diff --git a/arch/powerpc/mm/hash_native_64.c b/arch/powerpc/mm/hash_native_64.c
> index 6a2aead..8ca178d 100644
> --- a/arch/powerpc/mm/hash_native_64.c
> +++ b/arch/powerpc/mm/hash_native_64.c
> @@ -455,6 +455,83 @@ static void native_hpte_invalidate(unsigned long slot, unsigned long vpn,
>  	local_irq_restore(flags);
>  }
>  
> +static void native_hugepage_invalidate(struct mm_struct *mm,
> +				       unsigned char *hpte_slot_array,
> +				       unsigned long addr, int psize)
> +{
> +	int ssize = 0, i;
> +	int lock_tlbie;
> +	struct hash_pte *hptep;
> +	int actual_psize = MMU_PAGE_16M;
> +	unsigned int max_hpte_count, valid;
> +	unsigned long flags, s_addr = addr;
> +	unsigned long hpte_v, want_v, shift;
> +	unsigned long hidx, vpn = 0, vsid, hash, slot;
> +
> +	shift = mmu_psize_defs[psize].shift;
> +	max_hpte_count = HUGE_PAGE_SIZE >> shift;
> +
> +	local_irq_save(flags);
> +	for (i = 0; i < max_hpte_count; i++) {
> +		/*
> +		 * 8 bits per each hpte entries
> +		 * 000| [ secondary group (one bit) | hidx (3 bits) | valid bit]
> +		 */
> +		valid = hpte_slot_array[i] & 0x1;
> +		if (!valid)
> +			continue;
> +		hidx =  hpte_slot_array[i]  >> 1;
> +
> +		/* get the vpn */
> +		addr = s_addr + (i * (1ul << shift));
> +		if (!is_kernel_addr(addr)) {
> +			ssize = user_segment_size(addr);
> +			vsid = get_vsid(mm->context.id, addr, ssize);
> +			WARN_ON(vsid == 0);
> +		} else {
> +			vsid = get_kernel_vsid(addr, mmu_kernel_ssize);
> +			ssize = mmu_kernel_ssize;
> +		}
> +
> +		vpn = hpt_vpn(addr, vsid, ssize);
> +		hash = hpt_hash(vpn, shift, ssize);
> +		if (hidx & _PTEIDX_SECONDARY)
> +			hash = ~hash;
> +
> +		slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
> +		slot += hidx & _PTEIDX_GROUP_IX;
> +
> +		hptep = htab_address + slot;
> +		want_v = hpte_encode_avpn(vpn, psize, ssize);
> +		native_lock_hpte(hptep);
> +		hpte_v = hptep->v;
> +
> +		/* Even if we miss, we need to invalidate the TLB */
> +		if (!HPTE_V_COMPARE(hpte_v, want_v) || !(hpte_v & HPTE_V_VALID))
> +			native_unlock_hpte(hptep);
> +		else
> +			/* Invalidate the hpte. NOTE: this also unlocks it */
> +			hptep->v = 0;
> +	}
> +	/*
> +	 * Since this is a hugepage, we just need a single tlbie.
> +	 * use the last vpn.
> +	 */
> +	lock_tlbie = !mmu_has_feature(MMU_FTR_LOCKLESS_TLBIE);
> +	if (lock_tlbie)
> +		raw_spin_lock(&native_tlbie_lock);
> +
> +	asm volatile("ptesync":::"memory");
> +	__tlbie(vpn, psize, actual_psize, ssize);
> +	asm volatile("eieio; tlbsync; ptesync":::"memory");
> +
> +	if (lock_tlbie)
> +		raw_spin_unlock(&native_tlbie_lock);
> +
> +	local_irq_restore(flags);
> +}
> +
> +
>  static void hpte_decode(struct hash_pte *hpte, unsigned long slot,
>  			int *psize, int *apsize, int *ssize, unsigned long *vpn)
>  {
> @@ -658,4 +735,5 @@ void __init hpte_init_native(void)
>  	ppc_md.hpte_remove	= native_hpte_remove;
>  	ppc_md.hpte_clear_all	= native_hpte_clear;
>  	ppc_md.flush_hash_range = native_flush_hash_range;
> +	ppc_md.hugepage_invalidate   = native_hugepage_invalidate;
>  }
> diff --git a/arch/powerpc/mm/pgtable_64.c b/arch/powerpc/mm/pgtable_64.c
> index b742d6f..504952f 100644
> --- a/arch/powerpc/mm/pgtable_64.c
> +++ b/arch/powerpc/mm/pgtable_64.c
> @@ -659,6 +659,7 @@ void hpte_need_hugepage_flush(struct mm_struct *mm, unsigned long addr,
>  {
>  	int ssize, i;
>  	unsigned long s_addr;
> +	int max_hpte_count;
>  	unsigned int psize, valid;
>  	unsigned char *hpte_slot_array;
>  	unsigned long hidx, vpn, vsid, hash, shift, slot;
> @@ -672,12 +673,18 @@ void hpte_need_hugepage_flush(struct mm_struct *mm, unsigned long addr,
>  	 * second half of the PMD
>  	 */
>  	hpte_slot_array = *(char **)(pmdp + PTRS_PER_PMD);
> -
>  	/* get the base page size */
>  	psize = get_slice_psize(mm, s_addr);
> -	shift = mmu_psize_defs[psize].shift;
>  
> -	for (i = 0; i < (HUGE_PAGE_SIZE >> shift); i++) {
> +	if (ppc_md.hugepage_invalidate)
> +		return ppc_md.hugepage_invalidate(mm, hpte_slot_array,
> +						  s_addr, psize);
> +	/*
> +	 * No bluk hpte removal support, invalidate each entry
> +	 */
> +	shift = mmu_psize_defs[psize].shift;
> +	max_hpte_count = HUGE_PAGE_SIZE >> shift;
> +	for (i = 0; i < max_hpte_count; i++) {
>  		/*
>  		 * 8 bits per each hpte entries
>  		 * 000| [ secondary group (one bit) | hidx (3 bits) | valid bit]
> diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c
> index 6d62072..58a31db 100644
> --- a/arch/powerpc/platforms/pseries/lpar.c
> +++ b/arch/powerpc/platforms/pseries/lpar.c
> @@ -45,6 +45,13 @@
>  #include "plpar_wrappers.h"
>  #include "pseries.h"
>  
> +/* Flag bits for H_BULK_REMOVE */
> +#define HBR_REQUEST	0x4000000000000000UL
> +#define HBR_RESPONSE	0x8000000000000000UL
> +#define HBR_END		0xc000000000000000UL
> +#define HBR_AVPN	0x0200000000000000UL
> +#define HBR_ANDCOND	0x0100000000000000UL
> +
>  
>  /* in hvCall.S */
>  EXPORT_SYMBOL(plpar_hcall);
> @@ -345,6 +352,117 @@ static void pSeries_lpar_hpte_invalidate(unsigned long slot, unsigned long vpn,
>  	BUG_ON(lpar_rc != H_SUCCESS);
>  }
>  
> +/*
> + * Limit iterations holding pSeries_lpar_tlbie_lock to 3. We also need
> + * to make sure that we avoid bouncing the hypervisor tlbie lock.
> + */
> +#define PPC64_HUGE_HPTE_BATCH 12
> +
> +static void __pSeries_lpar_hugepage_invalidate(unsigned long *slot,
> +					     unsigned long *vpn, int count,
> +					     int psize, int ssize)
> +{
> +	unsigned long param[9];

[9]?  I only see 8 elements being used.

> +	int i = 0, pix = 0, rc;
> +	unsigned long flags = 0;
> +	int lock_tlbie = !mmu_has_feature(MMU_FTR_LOCKLESS_TLBIE);
> +
> +	if (lock_tlbie)
> +		spin_lock_irqsave(&pSeries_lpar_tlbie_lock, flags);

Why are these hash operations being called with the tlbie lock held?

> +
> +	for (i = 0; i < count; i++) {
> +
> +		if (!firmware_has_feature(FW_FEATURE_BULK_REMOVE)) {
> +			pSeries_lpar_hpte_invalidate(slot[i], vpn[i], psize,
> +						     ssize, 0);

Couldn't you set the ppc_md hook based on the firmware request to
avoid this test in the inner loop?  I don't see any tlbie operations
at all.

> +		} else {
> +			param[pix] = HBR_REQUEST | HBR_AVPN | slot[i];
> +			param[pix+1] = hpte_encode_avpn(vpn[i], psize, ssize);
> +			pix += 2;
> +			if (pix == 8) {
> +				rc = plpar_hcall9(H_BULK_REMOVE, param,
> +						  param[0], param[1], param[2],
> +						  param[3], param[4], param[5],
> +						  param[6], param[7]);
> +				BUG_ON(rc != H_SUCCESS);
> +				pix = 0;
> +			}
> +		}
> +	}
> +	if (pix) {
> +		param[pix] = HBR_END;
> +		rc = plpar_hcall9(H_BULK_REMOVE, param, param[0], param[1],
> +				  param[2], param[3], param[4], param[5],
> +				  param[6], param[7]);
> +		BUG_ON(rc != H_SUCCESS);
> +	}
> +
> +	if (lock_tlbie)
> +		spin_unlock_irqrestore(&pSeries_lpar_tlbie_lock, flags);
> +}
> +
> +static void pSeries_lpar_hugepage_invalidate(struct mm_struct *mm,
> +				       unsigned char *hpte_slot_array,
> +				       unsigned long addr, int psize)
> +{
> +	int ssize = 0, i, index = 0;
> +	unsigned long s_addr = addr;
> +	unsigned int max_hpte_count, valid;
> +	unsigned long vpn_array[PPC64_HUGE_HPTE_BATCH];
> +	unsigned long slot_array[PPC64_HUGE_HPTE_BATCH];
> +	unsigned long shift, hidx, vpn = 0, vsid, hash, slot;
> +
> +	shift = mmu_psize_defs[psize].shift;
> +	max_hpte_count = HUGE_PAGE_SIZE >> shift;
> +
> +	for (i = 0; i < max_hpte_count; i++) {
> +		/*
> +		 * 8 bits per each hpte entries
> +		 * 000| [ secondary group (one bit) | hidx (3 bits) | valid bit]
> +		 */
> +		valid = hpte_slot_array[i] & 0x1;
> +		if (!valid)
> +			continue;
> +		hidx =  hpte_slot_array[i]  >> 1;
> +
> +		/* get the vpn */
> +		addr = s_addr + (i * (1ul << shift));
> +		if (!is_kernel_addr(addr)) {
> +			ssize = user_segment_size(addr);
> +			vsid = get_vsid(mm->context.id, addr, ssize);
> +			WARN_ON(vsid == 0);
> +		} else {
> +			vsid = get_kernel_vsid(addr, mmu_kernel_ssize);
> +			ssize = mmu_kernel_ssize;
> +		}
> +
> +		vpn = hpt_vpn(addr, vsid, ssize);
> +		hash = hpt_hash(vpn, shift, ssize);
> +		if (hidx & _PTEIDX_SECONDARY)
> +			hash = ~hash;
> +
> +		slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
> +		slot += hidx & _PTEIDX_GROUP_IX;
> +
> +		slot_array[index] = slot;
> +		vpn_array[index] = vpn;
> +		if (index == PPC64_HUGE_HPTE_BATCH - 1) {
> +			/*
> +			 * Now do a bluk invalidate
> +			 */
> +			__pSeries_lpar_hugepage_invalidate(slot_array,
> +							   vpn_array,
> +							   PPC64_HUGE_HPTE_BATCH,
> +							   psize, ssize);

I don't really understand why you have one loop in this function, then
another in the __ function.

> +			index = 0;
> +		} else
> +			index++;
> +	}
> +	if (index)
> +		__pSeries_lpar_hugepage_invalidate(slot_array, vpn_array,
> +						   index, psize, ssize);
> +}
> +
>  static void pSeries_lpar_hpte_removebolted(unsigned long ea,
>  					   int psize, int ssize)
>  {
> @@ -360,13 +478,6 @@ static void pSeries_lpar_hpte_removebolted(unsigned long ea,
>  	pSeries_lpar_hpte_invalidate(slot, vpn, psize, ssize, 0);
>  }
>  
> -/* Flag bits for H_BULK_REMOVE */
> -#define HBR_REQUEST	0x4000000000000000UL
> -#define HBR_RESPONSE	0x8000000000000000UL
> -#define HBR_END		0xc000000000000000UL
> -#define HBR_AVPN	0x0200000000000000UL
> -#define HBR_ANDCOND	0x0100000000000000UL
> -
>  /*
>   * Take a spinlock around flushes to avoid bouncing the hypervisor tlbie
>   * lock.
> @@ -452,6 +563,7 @@ void __init hpte_init_lpar(void)
>  	ppc_md.hpte_removebolted = pSeries_lpar_hpte_removebolted;
>  	ppc_md.flush_hash_range	= pSeries_lpar_flush_hash_range;
>  	ppc_md.hpte_clear_all   = pSeries_lpar_hptab_clear;
> +	ppc_md.hugepage_invalidate = pSeries_lpar_hugepage_invalidate;
>  }
>  
>  #ifdef CONFIG_PPC_SMLPAR

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson
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