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Commit b31288fa authored by Konstantin Weitz's avatar Konstantin Weitz Committed by Martin Schwidefsky
Browse files

s390/kvm: support collaborative memory management 



This patch enables Collaborative Memory Management (CMM) for kvm
on s390. CMM allows the guest to inform the host about page usage
(see arch/s390/mm/cmm.c). The host uses this information to avoid
swapping in unused pages in the page fault handler. Further, a CPU
provided list of unused invalid pages is processed to reclaim swap
space of not yet accessed unused pages.

[ Martin Schwidefsky: patch reordering and cleanup ]

Signed-off-by: default avatarKonstantin Weitz <konstantin.weitz@gmail.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 45961722

arch/s390/include/asm/kvm_host.h

+4 −1
Original line number Diff line number Diff line
@@ -106,7 +106,9 @@ struct kvm_s390_sie_block { 
	__u64	gbea;			/* 0x0180 */

	__u8	reserved188[24];	/* 0x0188 */

	__u32	fac;			/* 0x01a0 */

	__u8	reserved1a4[68];	/* 0x01a4 */

	__u8	reserved1a4[20];	/* 0x01a4 */

	__u64	cbrlo;			/* 0x01b8 */

	__u8	reserved1c0[40];	/* 0x01c0 */

	__u64	itdba;			/* 0x01e8 */

	__u8	reserved1f0[16];	/* 0x01f0 */

} __attribute__((packed));
@@ -155,6 +157,7 @@ struct kvm_vcpu_stat { 
	u32 instruction_stsi;

	u32 instruction_stfl;

	u32 instruction_tprot;

	u32 instruction_essa;

	u32 instruction_sigp_sense;

	u32 instruction_sigp_sense_running;

	u32 instruction_sigp_external_call;

arch/s390/include/asm/pgtable.h

+26 −0
Original line number Diff line number Diff line
@@ -229,6 +229,7 @@ extern unsigned long MODULES_END; 
#define _PAGE_READ	0x010		/* SW pte read bit */

#define _PAGE_WRITE	0x020		/* SW pte write bit */

#define _PAGE_SPECIAL	0x040		/* SW associated with special page */

#define _PAGE_UNUSED	0x080		/* SW bit for pgste usage state */

#define __HAVE_ARCH_PTE_SPECIAL



/* Set of bits not changed in pte_modify */
@@ -394,6 +395,12 @@ extern unsigned long MODULES_END; 


#endif /* CONFIG_64BIT */



/* Guest Page State used for virtualization */

#define _PGSTE_GPS_ZERO		0x0000000080000000UL

#define _PGSTE_GPS_USAGE_MASK	0x0000000003000000UL

#define _PGSTE_GPS_USAGE_STABLE 0x0000000000000000UL

#define _PGSTE_GPS_USAGE_UNUSED 0x0000000001000000UL



/*

 * A user page table pointer has the space-switch-event bit, the

 * private-space-control bit and the storage-alteration-event-control
@@ -617,6 +624,14 @@ static inline int pte_none(pte_t pte) 
	return pte_val(pte) == _PAGE_INVALID;

}



static inline int pte_swap(pte_t pte)

{

	/* Bit pattern: (pte & 0x603) == 0x402 */

	return (pte_val(pte) & (_PAGE_INVALID | _PAGE_PROTECT |

				_PAGE_TYPE | _PAGE_PRESENT))

		== (_PAGE_INVALID | _PAGE_TYPE);

}



static inline int pte_file(pte_t pte)

{

	/* Bit pattern: (pte & 0x601) == 0x600 */
@@ -821,6 +836,7 @@ unsigned long gmap_translate(unsigned long address, struct gmap *); 
unsigned long __gmap_fault(unsigned long address, struct gmap *);

unsigned long gmap_fault(unsigned long address, struct gmap *);

void gmap_discard(unsigned long from, unsigned long to, struct gmap *);

void __gmap_zap(unsigned long address, struct gmap *);



void gmap_register_ipte_notifier(struct gmap_notifier *);

void gmap_unregister_ipte_notifier(struct gmap_notifier *);
@@ -852,6 +868,7 @@ static inline void set_pte_at(struct mm_struct *mm, unsigned long addr, 


	if (mm_has_pgste(mm)) {

		pgste = pgste_get_lock(ptep);

		pgste_val(pgste) &= ~_PGSTE_GPS_ZERO;

		pgste_set_key(ptep, pgste, entry);

		pgste_set_pte(ptep, entry);

		pgste_set_unlock(ptep, pgste);
@@ -881,6 +898,12 @@ static inline int pte_young(pte_t pte) 
	return (pte_val(pte) & _PAGE_YOUNG) != 0;

}



#define __HAVE_ARCH_PTE_UNUSED

static inline int pte_unused(pte_t pte)

{

	return pte_val(pte) & _PAGE_UNUSED;

}



/*

 * pgd/pmd/pte modification functions

 */
@@ -1196,6 +1219,9 @@ static inline pte_t ptep_clear_flush(struct vm_area_struct *vma, 
	pte_val(*ptep) = _PAGE_INVALID;



	if (mm_has_pgste(vma->vm_mm)) {

		if ((pgste_val(pgste) & _PGSTE_GPS_USAGE_MASK) ==

		    _PGSTE_GPS_USAGE_UNUSED)

			pte_val(pte) |= _PAGE_UNUSED;

		pgste = pgste_update_all(&pte, pgste);

		pgste_set_unlock(ptep, pgste);

	}

arch/s390/kvm/kvm-s390.c

+25 −0
Original line number Diff line number Diff line
@@ -68,6 +68,7 @@ struct kvm_stats_debugfs_item debugfs_entries[] = { 
	{ "instruction_storage_key", VCPU_STAT(instruction_storage_key) },

	{ "instruction_stsch", VCPU_STAT(instruction_stsch) },

	{ "instruction_chsc", VCPU_STAT(instruction_chsc) },

	{ "instruction_essa", VCPU_STAT(instruction_essa) },

	{ "instruction_stsi", VCPU_STAT(instruction_stsi) },

	{ "instruction_stfl", VCPU_STAT(instruction_stfl) },

	{ "instruction_tprot", VCPU_STAT(instruction_tprot) },
@@ -283,7 +284,11 @@ void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu) 
	if (kvm_is_ucontrol(vcpu->kvm))

		gmap_free(vcpu->arch.gmap);



	if (vcpu->arch.sie_block->cbrlo)

		__free_page(__pfn_to_page(

				vcpu->arch.sie_block->cbrlo >> PAGE_SHIFT));

	free_page((unsigned long)(vcpu->arch.sie_block));



	kvm_vcpu_uninit(vcpu);

	kmem_cache_free(kvm_vcpu_cache, vcpu);

}
@@ -390,6 +395,8 @@ int kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu) 


int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)

{

	struct page *cbrl;



	atomic_set(&vcpu->arch.sie_block->cpuflags, CPUSTAT_ZARCH |

						    CPUSTAT_SM |

						    CPUSTAT_STOPPED |
@@ -401,6 +408,14 @@ int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu) 
	vcpu->arch.sie_block->ecb2  = 8;

	vcpu->arch.sie_block->eca   = 0xC1002001U;

	vcpu->arch.sie_block->fac   = (int) (long) vfacilities;

	if (kvm_enabled_cmma()) {

		cbrl = alloc_page(GFP_KERNEL | __GFP_ZERO);

		if (cbrl) {

			vcpu->arch.sie_block->ecb2 |= 0x80;

			vcpu->arch.sie_block->ecb2 &= ~0x08;

			vcpu->arch.sie_block->cbrlo = page_to_phys(cbrl);

		}

	}

	hrtimer_init(&vcpu->arch.ckc_timer, CLOCK_REALTIME, HRTIMER_MODE_ABS);

	tasklet_init(&vcpu->arch.tasklet, kvm_s390_tasklet,

		     (unsigned long) vcpu);
@@ -761,6 +776,16 @@ static int vcpu_post_run(struct kvm_vcpu *vcpu, int exit_reason) 
	return rc;

}



bool kvm_enabled_cmma(void)

{

	if (!MACHINE_IS_LPAR)

		return false;

	/* only enable for z10 and later */

	if (!MACHINE_HAS_EDAT1)

		return false;

	return true;

}



static int __vcpu_run(struct kvm_vcpu *vcpu)

{

	int rc, exit_reason;

arch/s390/kvm/kvm-s390.h

+2 −0
Original line number Diff line number Diff line
@@ -156,6 +156,8 @@ void s390_vcpu_block(struct kvm_vcpu *vcpu); 
void s390_vcpu_unblock(struct kvm_vcpu *vcpu);

void exit_sie(struct kvm_vcpu *vcpu);

void exit_sie_sync(struct kvm_vcpu *vcpu);

/* are we going to support cmma? */

bool kvm_enabled_cmma(void);

/* implemented in diag.c */

int kvm_s390_handle_diag(struct kvm_vcpu *vcpu);

arch/s390/kvm/priv.c

+41 −0
Original line number Diff line number Diff line
@@ -636,8 +636,49 @@ static int handle_pfmf(struct kvm_vcpu *vcpu) 
	return 0;

}



static int handle_essa(struct kvm_vcpu *vcpu)

{

	/* entries expected to be 1FF */

	int entries = (vcpu->arch.sie_block->cbrlo & ~PAGE_MASK) >> 3;

	unsigned long *cbrlo, cbrle;

	struct gmap *gmap;

	int i;



	VCPU_EVENT(vcpu, 5, "cmma release %d pages", entries);

	gmap = vcpu->arch.gmap;

	vcpu->stat.instruction_essa++;

	if (!kvm_enabled_cmma() || !vcpu->arch.sie_block->cbrlo)

		return kvm_s390_inject_program_int(vcpu, PGM_OPERATION);



	if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PSTATE)

		return kvm_s390_inject_program_int(vcpu, PGM_PRIVILEGED_OP);



	if (((vcpu->arch.sie_block->ipb & 0xf0000000) >> 28) > 6)

		return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);



	/* Rewind PSW to repeat the ESSA instruction */

	vcpu->arch.sie_block->gpsw.addr =

		__rewind_psw(vcpu->arch.sie_block->gpsw, 4);

	vcpu->arch.sie_block->cbrlo &= PAGE_MASK;	/* reset nceo */

	cbrlo = phys_to_virt(vcpu->arch.sie_block->cbrlo);

	down_read(&gmap->mm->mmap_sem);

	for (i = 0; i < entries; ++i) {

		cbrle = cbrlo[i];

		if (unlikely(cbrle & ~PAGE_MASK || cbrle < 2 * PAGE_SIZE))

			/* invalid entry */

			break;

		/* try to free backing */

		__gmap_zap(cbrle, gmap);

	}

	up_read(&gmap->mm->mmap_sem);

	if (i < entries)

		return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);

	return 0;

}



static const intercept_handler_t b9_handlers[256] = {

	[0x8d] = handle_epsw,

	[0xab] = handle_essa,

	[0xaf] = handle_pfmf,

};