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: Konstantin Weitz <konstantin.weitz@gmail.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>hifive-unleashed-5.1
Konstantin Weitz
Martin Schwidefsky
parent
45961722f8
commit
b31288fa83
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@ -106,7 +106,9 @@ struct kvm_s390_sie_block {
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__u64 gbea; /* 0x0180 */
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__u8 reserved188[24]; /* 0x0188 */
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__u32 fac; /* 0x01a0 */
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__u8 reserved1a4[68]; /* 0x01a4 */
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__u8 reserved1a4[20]; /* 0x01a4 */
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__u64 cbrlo; /* 0x01b8 */
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__u8 reserved1c0[40]; /* 0x01c0 */
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__u64 itdba; /* 0x01e8 */
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__u8 reserved1f0[16]; /* 0x01f0 */
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} __attribute__((packed));
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@ -155,6 +157,7 @@ struct kvm_vcpu_stat {
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u32 instruction_stsi;
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u32 instruction_stfl;
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u32 instruction_tprot;
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u32 instruction_essa;
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u32 instruction_sigp_sense;
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u32 instruction_sigp_sense_running;
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u32 instruction_sigp_external_call;
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@ -229,6 +229,7 @@ extern unsigned long MODULES_END;
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#define _PAGE_READ 0x010 /* SW pte read bit */
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#define _PAGE_WRITE 0x020 /* SW pte write bit */
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#define _PAGE_SPECIAL 0x040 /* SW associated with special page */
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#define _PAGE_UNUSED 0x080 /* SW bit for pgste usage state */
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#define __HAVE_ARCH_PTE_SPECIAL
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/* Set of bits not changed in pte_modify */
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@ -394,6 +395,12 @@ extern unsigned long MODULES_END;
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#endif /* CONFIG_64BIT */
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/* Guest Page State used for virtualization */
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#define _PGSTE_GPS_ZERO 0x0000000080000000UL
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#define _PGSTE_GPS_USAGE_MASK 0x0000000003000000UL
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#define _PGSTE_GPS_USAGE_STABLE 0x0000000000000000UL
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#define _PGSTE_GPS_USAGE_UNUSED 0x0000000001000000UL
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/*
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* A user page table pointer has the space-switch-event bit, the
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* private-space-control bit and the storage-alteration-event-control
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@ -617,6 +624,14 @@ static inline int pte_none(pte_t pte)
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return pte_val(pte) == _PAGE_INVALID;
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}
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static inline int pte_swap(pte_t pte)
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{
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/* Bit pattern: (pte & 0x603) == 0x402 */
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return (pte_val(pte) & (_PAGE_INVALID | _PAGE_PROTECT |
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_PAGE_TYPE | _PAGE_PRESENT))
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== (_PAGE_INVALID | _PAGE_TYPE);
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}
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static inline int pte_file(pte_t pte)
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{
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/* Bit pattern: (pte & 0x601) == 0x600 */
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@ -821,6 +836,7 @@ unsigned long gmap_translate(unsigned long address, struct gmap *);
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unsigned long __gmap_fault(unsigned long address, struct gmap *);
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unsigned long gmap_fault(unsigned long address, struct gmap *);
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void gmap_discard(unsigned long from, unsigned long to, struct gmap *);
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void __gmap_zap(unsigned long address, struct gmap *);
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void gmap_register_ipte_notifier(struct gmap_notifier *);
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void gmap_unregister_ipte_notifier(struct gmap_notifier *);
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@ -852,6 +868,7 @@ static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
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if (mm_has_pgste(mm)) {
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pgste = pgste_get_lock(ptep);
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pgste_val(pgste) &= ~_PGSTE_GPS_ZERO;
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pgste_set_key(ptep, pgste, entry);
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pgste_set_pte(ptep, entry);
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pgste_set_unlock(ptep, pgste);
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@ -881,6 +898,12 @@ static inline int pte_young(pte_t pte)
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return (pte_val(pte) & _PAGE_YOUNG) != 0;
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}
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#define __HAVE_ARCH_PTE_UNUSED
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static inline int pte_unused(pte_t pte)
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{
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return pte_val(pte) & _PAGE_UNUSED;
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}
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/*
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* pgd/pmd/pte modification functions
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*/
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@ -1196,6 +1219,9 @@ static inline pte_t ptep_clear_flush(struct vm_area_struct *vma,
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pte_val(*ptep) = _PAGE_INVALID;
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if (mm_has_pgste(vma->vm_mm)) {
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if ((pgste_val(pgste) & _PGSTE_GPS_USAGE_MASK) ==
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_PGSTE_GPS_USAGE_UNUSED)
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pte_val(pte) |= _PAGE_UNUSED;
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pgste = pgste_update_all(&pte, pgste);
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pgste_set_unlock(ptep, pgste);
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}
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@ -68,6 +68,7 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
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{ "instruction_storage_key", VCPU_STAT(instruction_storage_key) },
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{ "instruction_stsch", VCPU_STAT(instruction_stsch) },
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{ "instruction_chsc", VCPU_STAT(instruction_chsc) },
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{ "instruction_essa", VCPU_STAT(instruction_essa) },
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{ "instruction_stsi", VCPU_STAT(instruction_stsi) },
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{ "instruction_stfl", VCPU_STAT(instruction_stfl) },
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{ "instruction_tprot", VCPU_STAT(instruction_tprot) },
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@ -283,7 +284,11 @@ void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
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if (kvm_is_ucontrol(vcpu->kvm))
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gmap_free(vcpu->arch.gmap);
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if (vcpu->arch.sie_block->cbrlo)
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__free_page(__pfn_to_page(
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vcpu->arch.sie_block->cbrlo >> PAGE_SHIFT));
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free_page((unsigned long)(vcpu->arch.sie_block));
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kvm_vcpu_uninit(vcpu);
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kmem_cache_free(kvm_vcpu_cache, vcpu);
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}
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@ -390,6 +395,8 @@ int kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu)
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int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
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{
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struct page *cbrl;
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atomic_set(&vcpu->arch.sie_block->cpuflags, CPUSTAT_ZARCH |
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CPUSTAT_SM |
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CPUSTAT_STOPPED |
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@ -401,6 +408,14 @@ int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
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vcpu->arch.sie_block->ecb2 = 8;
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vcpu->arch.sie_block->eca = 0xC1002001U;
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vcpu->arch.sie_block->fac = (int) (long) vfacilities;
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if (kvm_enabled_cmma()) {
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cbrl = alloc_page(GFP_KERNEL | __GFP_ZERO);
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if (cbrl) {
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vcpu->arch.sie_block->ecb2 |= 0x80;
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vcpu->arch.sie_block->ecb2 &= ~0x08;
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vcpu->arch.sie_block->cbrlo = page_to_phys(cbrl);
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}
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}
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hrtimer_init(&vcpu->arch.ckc_timer, CLOCK_REALTIME, HRTIMER_MODE_ABS);
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tasklet_init(&vcpu->arch.tasklet, kvm_s390_tasklet,
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(unsigned long) vcpu);
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@ -761,6 +776,16 @@ static int vcpu_post_run(struct kvm_vcpu *vcpu, int exit_reason)
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return rc;
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}
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bool kvm_enabled_cmma(void)
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{
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if (!MACHINE_IS_LPAR)
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return false;
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/* only enable for z10 and later */
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if (!MACHINE_HAS_EDAT1)
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return false;
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return true;
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}
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static int __vcpu_run(struct kvm_vcpu *vcpu)
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{
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int rc, exit_reason;
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@ -156,6 +156,8 @@ void s390_vcpu_block(struct kvm_vcpu *vcpu);
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void s390_vcpu_unblock(struct kvm_vcpu *vcpu);
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void exit_sie(struct kvm_vcpu *vcpu);
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void exit_sie_sync(struct kvm_vcpu *vcpu);
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/* are we going to support cmma? */
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bool kvm_enabled_cmma(void);
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/* implemented in diag.c */
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int kvm_s390_handle_diag(struct kvm_vcpu *vcpu);
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@ -636,8 +636,49 @@ static int handle_pfmf(struct kvm_vcpu *vcpu)
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return 0;
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}
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static int handle_essa(struct kvm_vcpu *vcpu)
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{
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/* entries expected to be 1FF */
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int entries = (vcpu->arch.sie_block->cbrlo & ~PAGE_MASK) >> 3;
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unsigned long *cbrlo, cbrle;
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struct gmap *gmap;
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int i;
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VCPU_EVENT(vcpu, 5, "cmma release %d pages", entries);
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gmap = vcpu->arch.gmap;
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vcpu->stat.instruction_essa++;
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if (!kvm_enabled_cmma() || !vcpu->arch.sie_block->cbrlo)
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return kvm_s390_inject_program_int(vcpu, PGM_OPERATION);
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if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PSTATE)
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return kvm_s390_inject_program_int(vcpu, PGM_PRIVILEGED_OP);
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if (((vcpu->arch.sie_block->ipb & 0xf0000000) >> 28) > 6)
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return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
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/* Rewind PSW to repeat the ESSA instruction */
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vcpu->arch.sie_block->gpsw.addr =
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__rewind_psw(vcpu->arch.sie_block->gpsw, 4);
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vcpu->arch.sie_block->cbrlo &= PAGE_MASK; /* reset nceo */
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cbrlo = phys_to_virt(vcpu->arch.sie_block->cbrlo);
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down_read(&gmap->mm->mmap_sem);
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for (i = 0; i < entries; ++i) {
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cbrle = cbrlo[i];
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if (unlikely(cbrle & ~PAGE_MASK || cbrle < 2 * PAGE_SIZE))
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/* invalid entry */
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break;
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/* try to free backing */
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__gmap_zap(cbrle, gmap);
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}
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up_read(&gmap->mm->mmap_sem);
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if (i < entries)
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return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
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return 0;
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}
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static const intercept_handler_t b9_handlers[256] = {
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[0x8d] = handle_epsw,
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[0xab] = handle_essa,
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[0xaf] = handle_pfmf,
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};
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@ -17,6 +17,7 @@
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#include <linux/quicklist.h>
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#include <linux/rcupdate.h>
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#include <linux/slab.h>
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#include <linux/swapops.h>
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#include <asm/pgtable.h>
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#include <asm/pgalloc.h>
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@ -594,6 +595,82 @@ unsigned long gmap_fault(unsigned long address, struct gmap *gmap)
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}
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EXPORT_SYMBOL_GPL(gmap_fault);
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static void gmap_zap_swap_entry(swp_entry_t entry, struct mm_struct *mm)
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{
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if (!non_swap_entry(entry))
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dec_mm_counter(mm, MM_SWAPENTS);
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else if (is_migration_entry(entry)) {
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struct page *page = migration_entry_to_page(entry);
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if (PageAnon(page))
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dec_mm_counter(mm, MM_ANONPAGES);
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else
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dec_mm_counter(mm, MM_FILEPAGES);
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}
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free_swap_and_cache(entry);
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}
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/**
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* The mm->mmap_sem lock must be held
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*/
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static void gmap_zap_unused(struct mm_struct *mm, unsigned long address)
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{
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unsigned long ptev, pgstev;
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spinlock_t *ptl;
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pgste_t pgste;
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pte_t *ptep, pte;
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ptep = get_locked_pte(mm, address, &ptl);
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if (unlikely(!ptep))
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return;
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pte = *ptep;
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if (!pte_swap(pte))
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goto out_pte;
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/* Zap unused and logically-zero pages */
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pgste = pgste_get_lock(ptep);
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pgstev = pgste_val(pgste);
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ptev = pte_val(pte);
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if (((pgstev & _PGSTE_GPS_USAGE_MASK) == _PGSTE_GPS_USAGE_UNUSED) ||
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((pgstev & _PGSTE_GPS_ZERO) && (ptev & _PAGE_INVALID))) {
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gmap_zap_swap_entry(pte_to_swp_entry(pte), mm);
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pte_clear(mm, address, ptep);
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}
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pgste_set_unlock(ptep, pgste);
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out_pte:
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pte_unmap_unlock(*ptep, ptl);
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}
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/*
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* this function is assumed to be called with mmap_sem held
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*/
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void __gmap_zap(unsigned long address, struct gmap *gmap)
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{
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unsigned long *table, *segment_ptr;
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unsigned long segment, pgstev, ptev;
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struct gmap_pgtable *mp;
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struct page *page;
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segment_ptr = gmap_table_walk(address, gmap);
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if (IS_ERR(segment_ptr))
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return;
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segment = *segment_ptr;
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if (segment & _SEGMENT_ENTRY_INVALID)
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return;
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page = pfn_to_page(segment >> PAGE_SHIFT);
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mp = (struct gmap_pgtable *) page->index;
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address = mp->vmaddr | (address & ~PMD_MASK);
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/* Page table is present */
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table = (unsigned long *)(segment & _SEGMENT_ENTRY_ORIGIN);
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table = table + ((address >> 12) & 0xff);
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pgstev = table[PTRS_PER_PTE];
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ptev = table[0];
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/* quick check, checked again with locks held */
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if (((pgstev & _PGSTE_GPS_USAGE_MASK) == _PGSTE_GPS_USAGE_UNUSED) ||
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((pgstev & _PGSTE_GPS_ZERO) && (ptev & _PAGE_INVALID)))
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gmap_zap_unused(gmap->mm, address);
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}
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EXPORT_SYMBOL_GPL(__gmap_zap);
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void gmap_discard(unsigned long from, unsigned long to, struct gmap *gmap)
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{
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