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Commit 1b948d6c authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

s390/mm,tlb: optimize TLB flushing for zEC12 



The zEC12 machines introduced the local-clearing control for the IDTE
and IPTE instruction. If the control is set only the TLB of the local
CPU is cleared of entries, either all entries of a single address space
for IDTE, or the entry for a single page-table entry for IPTE.
Without the local-clearing control the TLB flush is broadcasted to all
CPUs in the configuration, which is expensive.

The reset of the bit mask of the CPUs that need flushing after a
non-local IDTE is tricky. As TLB entries for an address space remain
in the TLB even if the address space is detached a new bit field is
required to keep track of attached CPUs vs. CPUs in the need of a
flush. After a non-local flush with IDTE the bit-field of attached CPUs
is copied to the bit-field of CPUs in need of a flush. The ordering
of operations on cpu_attach_mask, attach_count and mm_cpumask(mm) is
such that an underindication in mm_cpumask(mm) is prevented but an
overindication in mm_cpumask(mm) is possible.

Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 02a8f3ab

arch/s390/include/asm/mmu.h

+2 −0
Original line number Diff line number Diff line 
#ifndef __MMU_H

#define __MMU_H



#include <linux/cpumask.h>

#include <linux/errno.h>



typedef struct {

	cpumask_t cpu_attach_mask;

	atomic_t attach_count;

	unsigned int flush_mm;

	spinlock_t list_lock;

arch/s390/include/asm/mmu_context.h

+5 −0
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ 
static inline int init_new_context(struct task_struct *tsk,

				   struct mm_struct *mm)

{

	cpumask_clear(&mm->context.cpu_attach_mask);

	atomic_set(&mm->context.attach_count, 0);

	mm->context.flush_mm = 0;

	mm->context.asce_bits = _ASCE_TABLE_LENGTH | _ASCE_USER_BITS;
@@ -59,6 +60,8 @@ static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next, 


	if (prev == next)

		return;

	if (MACHINE_HAS_TLB_LC)

		cpumask_set_cpu(cpu, &next->context.cpu_attach_mask);

	if (atomic_inc_return(&next->context.attach_count) >> 16) {

		/* Delay update_user_asce until all TLB flushes are done. */

		set_tsk_thread_flag(tsk, TIF_TLB_WAIT);
@@ -73,6 +76,8 @@ static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next, 
	}

	atomic_dec(&prev->context.attach_count);

	WARN_ON(atomic_read(&prev->context.attach_count) < 0);

	if (MACHINE_HAS_TLB_LC)

		cpumask_clear_cpu(cpu, &prev->context.cpu_attach_mask);

}



#define finish_arch_post_lock_switch finish_arch_post_lock_switch

arch/s390/include/asm/pgtable.h

+92 −36
Original line number Diff line number Diff line
@@ -1068,12 +1068,35 @@ static inline void __ptep_ipte(unsigned long address, pte_t *ptep) 
		: "=m" (*ptep) : "m" (*ptep), "a" (pto), "a" (address));

}



static inline void __ptep_ipte_local(unsigned long address, pte_t *ptep)

{

	unsigned long pto = (unsigned long) ptep;



#ifndef CONFIG_64BIT

	/* pto in ESA mode must point to the start of the segment table */

	pto &= 0x7ffffc00;

#endif

	/* Invalidation + local TLB flush for the pte */

	asm volatile(

		"	.insn rrf,0xb2210000,%2,%3,0,1"

		: "=m" (*ptep) : "m" (*ptep), "a" (pto), "a" (address));

}



static inline void ptep_flush_direct(struct mm_struct *mm,

				     unsigned long address, pte_t *ptep)

{

	int active, count;



	if (pte_val(*ptep) & _PAGE_INVALID)

		return;

	active = (mm == current->active_mm) ? 1 : 0;

	count = atomic_add_return(0x10000, &mm->context.attach_count);

	if (MACHINE_HAS_TLB_LC && (count & 0xffff) <= active &&

	    cpumask_equal(mm_cpumask(mm), cpumask_of(smp_processor_id())))

		__ptep_ipte_local(address, ptep);

	else

		__ptep_ipte(address, ptep);

	atomic_sub(0x10000, &mm->context.attach_count);

}



static inline void ptep_flush_lazy(struct mm_struct *mm,
@@ -1382,35 +1405,6 @@ static inline pmd_t *pmd_offset(pud_t *pud, unsigned long address) 
#define pte_offset_map(pmd, address) pte_offset_kernel(pmd, address)

#define pte_unmap(pte) do { } while (0)



static inline void __pmd_idte(unsigned long address, pmd_t *pmdp)

{

	unsigned long sto = (unsigned long) pmdp -

			    pmd_index(address) * sizeof(pmd_t);



	if (!(pmd_val(*pmdp) & _SEGMENT_ENTRY_INVALID)) {

		asm volatile(

			"	.insn	rrf,0xb98e0000,%2,%3,0,0"

			: "=m" (*pmdp)

			: "m" (*pmdp), "a" (sto),

			  "a" ((address & HPAGE_MASK))

			: "cc"

		);

	}

}



static inline void __pmd_csp(pmd_t *pmdp)

{

	register unsigned long reg2 asm("2") = pmd_val(*pmdp);

	register unsigned long reg3 asm("3") = pmd_val(*pmdp) |

					       _SEGMENT_ENTRY_INVALID;

	register unsigned long reg4 asm("4") = ((unsigned long) pmdp) + 5;



	asm volatile(

		"	csp %1,%3"

		: "=m" (*pmdp)

		: "d" (reg2), "d" (reg3), "d" (reg4), "m" (*pmdp) : "cc");

}



#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLB_PAGE)

static inline unsigned long massage_pgprot_pmd(pgprot_t pgprot)

{
@@ -1479,18 +1473,80 @@ static inline pmd_t pmd_mkwrite(pmd_t pmd) 
}

#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLB_PAGE */



static inline void __pmdp_csp(pmd_t *pmdp)

{

	register unsigned long reg2 asm("2") = pmd_val(*pmdp);

	register unsigned long reg3 asm("3") = pmd_val(*pmdp) |

					       _SEGMENT_ENTRY_INVALID;

	register unsigned long reg4 asm("4") = ((unsigned long) pmdp) + 5;



	asm volatile(

		"	csp %1,%3"

		: "=m" (*pmdp)

		: "d" (reg2), "d" (reg3), "d" (reg4), "m" (*pmdp) : "cc");

}



static inline void __pmdp_idte(unsigned long address, pmd_t *pmdp)

{

	unsigned long sto;



	sto = (unsigned long) pmdp - pmd_index(address) * sizeof(pmd_t);

	asm volatile(

		"	.insn	rrf,0xb98e0000,%2,%3,0,0"

		: "=m" (*pmdp)

		: "m" (*pmdp), "a" (sto), "a" ((address & HPAGE_MASK))

		: "cc" );

}



static inline void __pmdp_idte_local(unsigned long address, pmd_t *pmdp)

{

	unsigned long sto;



	sto = (unsigned long) pmdp - pmd_index(address) * sizeof(pmd_t);

	asm volatile(

		"	.insn	rrf,0xb98e0000,%2,%3,0,1"

		: "=m" (*pmdp)

		: "m" (*pmdp), "a" (sto), "a" ((address & HPAGE_MASK))

		: "cc" );

}



static inline void pmdp_flush_direct(struct mm_struct *mm,

				     unsigned long address, pmd_t *pmdp)

{

	int active, count;



	if (pmd_val(*pmdp) & _SEGMENT_ENTRY_INVALID)

		return;

	if (!MACHINE_HAS_IDTE) {

		__pmdp_csp(pmdp);

		return;

	}

	active = (mm == current->active_mm) ? 1 : 0;

	count = atomic_add_return(0x10000, &mm->context.attach_count);

	if (MACHINE_HAS_TLB_LC && (count & 0xffff) <= active &&

	    cpumask_equal(mm_cpumask(mm), cpumask_of(smp_processor_id())))

		__pmdp_idte_local(address, pmdp);

	else

		__pmdp_idte(address, pmdp);

	atomic_sub(0x10000, &mm->context.attach_count);

}



static inline void pmdp_flush_lazy(struct mm_struct *mm,

				   unsigned long address, pmd_t *pmdp)

{

	int active, count;



	if (pmd_val(*pmdp) & _SEGMENT_ENTRY_INVALID)

		return;

	active = (mm == current->active_mm) ? 1 : 0;

	count = atomic_add_return(0x10000, &mm->context.attach_count);

	if ((count & 0xffff) <= active) {

		pmd_val(*pmdp) |= _SEGMENT_ENTRY_INVALID;

		mm->context.flush_mm = 1;

	} else

		__pmd_idte(address, pmdp);

	} else if (MACHINE_HAS_IDTE)

		__pmdp_idte(address, pmdp);

	else

		__pmdp_csp(pmdp);

	atomic_sub(0x10000, &mm->context.attach_count);

}
@@ -1543,7 +1599,7 @@ static inline int pmdp_test_and_clear_young(struct vm_area_struct *vma, 
	pmd_t pmd;



	pmd = *pmdp;

	__pmd_idte(address, pmdp);

	pmdp_flush_direct(vma->vm_mm, address, pmdp);

	*pmdp = pmd_mkold(pmd);

	return pmd_young(pmd);

}
@@ -1554,7 +1610,7 @@ static inline pmd_t pmdp_get_and_clear(struct mm_struct *mm, 
{

	pmd_t pmd = *pmdp;



	__pmd_idte(address, pmdp);

	pmdp_flush_direct(mm, address, pmdp);

	pmd_clear(pmdp);

	return pmd;

}
@@ -1570,7 +1626,7 @@ static inline pmd_t pmdp_clear_flush(struct vm_area_struct *vma, 
static inline void pmdp_invalidate(struct vm_area_struct *vma,

				   unsigned long address, pmd_t *pmdp)

{

	__pmd_idte(address, pmdp);

	pmdp_flush_direct(vma->vm_mm, address, pmdp);

}



#define __HAVE_ARCH_PMDP_SET_WRPROTECT
@@ -1580,7 +1636,7 @@ static inline void pmdp_set_wrprotect(struct mm_struct *mm, 
	pmd_t pmd = *pmdp;



	if (pmd_write(pmd)) {

		__pmd_idte(address, pmdp);

		pmdp_flush_direct(mm, address, pmdp);

		set_pmd_at(mm, address, pmdp, pmd_wrprotect(pmd));

	}

}

arch/s390/include/asm/setup.h

+3 −0
Original line number Diff line number Diff line
@@ -68,6 +68,7 @@ void create_mem_hole(struct mem_chunk mem_chunk[], unsigned long addr, 
#define MACHINE_FLAG_TOPOLOGY	(1UL << 14)

#define MACHINE_FLAG_TE		(1UL << 15)

#define MACHINE_FLAG_RRBM	(1UL << 16)

#define MACHINE_FLAG_TLB_LC	(1UL << 17)



#define MACHINE_IS_VM		(S390_lowcore.machine_flags & MACHINE_FLAG_VM)

#define MACHINE_IS_KVM		(S390_lowcore.machine_flags & MACHINE_FLAG_KVM)
@@ -90,6 +91,7 @@ void create_mem_hole(struct mem_chunk mem_chunk[], unsigned long addr, 
#define MACHINE_HAS_TOPOLOGY	(0)

#define MACHINE_HAS_TE		(0)

#define MACHINE_HAS_RRBM	(0)

#define MACHINE_HAS_TLB_LC	(0)

#else /* CONFIG_64BIT */

#define MACHINE_HAS_IEEE	(1)

#define MACHINE_HAS_CSP		(1)
@@ -102,6 +104,7 @@ void create_mem_hole(struct mem_chunk mem_chunk[], unsigned long addr, 
#define MACHINE_HAS_TOPOLOGY	(S390_lowcore.machine_flags & MACHINE_FLAG_TOPOLOGY)

#define MACHINE_HAS_TE		(S390_lowcore.machine_flags & MACHINE_FLAG_TE)

#define MACHINE_HAS_RRBM	(S390_lowcore.machine_flags & MACHINE_FLAG_RRBM)

#define MACHINE_HAS_TLB_LC	(S390_lowcore.machine_flags & MACHINE_FLAG_TLB_LC)

#endif /* CONFIG_64BIT */



/*

arch/s390/include/asm/tlbflush.h

+95 −20
Original line number Diff line number Diff line
@@ -7,19 +7,41 @@ 
#include <asm/pgalloc.h>



/*

 * Flush all tlb entries on the local cpu.

 * Flush all TLB entries on the local CPU.

 */

static inline void __tlb_flush_local(void)

{

	asm volatile("ptlb" : : : "memory");

}



#ifdef CONFIG_SMP

/*

 * Flush all tlb entries on all cpus.

 * Flush TLB entries for a specific ASCE on all CPUs

 */

static inline void __tlb_flush_idte(unsigned long asce)

{

	/* Global TLB flush for the mm */

	asm volatile(

		"	.insn	rrf,0xb98e0000,0,%0,%1,0"

		: : "a" (2048), "a" (asce) : "cc");

}



/*

 * Flush TLB entries for a specific ASCE on the local CPU

 */

static inline void __tlb_flush_idte_local(unsigned long asce)

{

	/* Local TLB flush for the mm */

	asm volatile(

		"	.insn	rrf,0xb98e0000,0,%0,%1,1"

		: : "a" (2048), "a" (asce) : "cc");

}



#ifdef CONFIG_SMP

void smp_ptlb_all(void);



/*

 * Flush all TLB entries on all CPUs.

 */

static inline void __tlb_flush_global(void)

{

	register unsigned long reg2 asm("2");
@@ -42,36 +64,89 @@ static inline void __tlb_flush_global(void) 
		: : "d" (reg2), "d" (reg3), "d" (reg4), "m" (dummy) : "cc" );

}



/*

 * Flush TLB entries for a specific mm on all CPUs (in case gmap is used

 * this implicates multiple ASCEs!).

 */

static inline void __tlb_flush_full(struct mm_struct *mm)

{

	cpumask_t local_cpumask;



	preempt_disable();

	atomic_add(0x10000, &mm->context.attach_count);

	if (cpumask_equal(mm_cpumask(mm), cpumask_of(smp_processor_id()))) {

		/* Local TLB flush */

		__tlb_flush_local();

	} else {

		/* Global TLB flush */

		__tlb_flush_global();

		/* Reset TLB flush mask */

		if (MACHINE_HAS_TLB_LC)

			cpumask_copy(mm_cpumask(mm),

				     &mm->context.cpu_attach_mask);

	}

	atomic_sub(0x10000, &mm->context.attach_count);

	preempt_enable();

}



/*

	 * If the process only ran on the local cpu, do a local flush.

 * Flush TLB entries for a specific ASCE on all CPUs.

 */

	cpumask_copy(&local_cpumask, cpumask_of(smp_processor_id()));

	if (cpumask_equal(mm_cpumask(mm), &local_cpumask))

		__tlb_flush_local();

static inline void __tlb_flush_asce(struct mm_struct *mm, unsigned long asce)

{

	int active, count;



	preempt_disable();

	active = (mm == current->active_mm) ? 1 : 0;

	count = atomic_add_return(0x10000, &mm->context.attach_count);

	if (MACHINE_HAS_TLB_LC && (count & 0xffff) <= active &&

	    cpumask_equal(mm_cpumask(mm), cpumask_of(smp_processor_id()))) {

		__tlb_flush_idte_local(asce);

	} else {

		if (MACHINE_HAS_IDTE)

			__tlb_flush_idte(asce);

		else

			__tlb_flush_global();

		/* Reset TLB flush mask */

		if (MACHINE_HAS_TLB_LC)

			cpumask_copy(mm_cpumask(mm),

				     &mm->context.cpu_attach_mask);

	}

	atomic_sub(0x10000, &mm->context.attach_count);

	preempt_enable();

}



static inline void __tlb_flush_kernel(void)

{

	if (MACHINE_HAS_IDTE)

		__tlb_flush_idte((unsigned long) init_mm.pgd |

				 init_mm.context.asce_bits);

	else

		__tlb_flush_global();

}

#else

#define __tlb_flush_full(mm)	__tlb_flush_local()

#define __tlb_flush_global()	__tlb_flush_local()

#endif

#define __tlb_flush_full(mm)	__tlb_flush_local()



/*

 * Flush all tlb entries of a page table on all cpus.

 * Flush TLB entries for a specific ASCE on all CPUs.

 */

static inline void __tlb_flush_idte(unsigned long asce)

static inline void __tlb_flush_asce(struct mm_struct *mm, unsigned long asce)

{

	asm volatile(

		"	.insn	rrf,0xb98e0000,0,%0,%1,0"

		: : "a" (2048), "a" (asce) : "cc" );

	if (MACHINE_HAS_TLB_LC)

		__tlb_flush_idte_local(asce);

	else

		__tlb_flush_local();

}



static inline void __tlb_flush_kernel(void)

{

	if (MACHINE_HAS_TLB_LC)

		__tlb_flush_idte_local((unsigned long) init_mm.pgd |

				       init_mm.context.asce_bits);

	else

		__tlb_flush_local();

}

#endif



static inline void __tlb_flush_mm(struct mm_struct * mm)

{

	/*
@@ -80,7 +155,7 @@ static inline void __tlb_flush_mm(struct mm_struct * mm) 
	 * only ran on the local cpu.

	 */

	if (MACHINE_HAS_IDTE && list_empty(&mm->context.gmap_list))

		__tlb_flush_idte((unsigned long) mm->pgd |

		__tlb_flush_asce(mm, (unsigned long) mm->pgd |

				 mm->context.asce_bits);

	else

		__tlb_flush_full(mm);
@@ -130,7 +205,7 @@ static inline void flush_tlb_range(struct vm_area_struct *vma, 
static inline void flush_tlb_kernel_range(unsigned long start,

					  unsigned long end)

{

	__tlb_flush_mm(&init_mm);

	__tlb_flush_kernel();

}



#endif /* _S390_TLBFLUSH_H */