The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From b31288fa83b2bcc8834e1e208e9526b8bd5ce361 Mon Sep 17 00:00:00 2001
From: Konstantin Weitz konstantin.weitz@gmail.com Date: Wed, 17 Apr 2013 17:36:29 +0200 Subject: [PATCH] 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
diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h index eef3dd3fd9a9..9bf95bb30f1a 100644 --- a/arch/s390/include/asm/kvm_host.h +++ b/arch/s390/include/asm/kvm_host.h @@ -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; diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h index fc4bb82a0739..a7dd672c97f8 100644 --- a/arch/s390/include/asm/pgtable.h +++ b/arch/s390/include/asm/pgtable.h @@ -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); } diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index e0676f390d57..10b5db3c9bc4 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -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; diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h index f9559b0bd620..564514f410f4 100644 --- a/arch/s390/kvm/kvm-s390.h +++ b/arch/s390/kvm/kvm-s390.h @@ -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);
diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c index 75beea632a10..aacb6b129914 100644 --- a/arch/s390/kvm/priv.c +++ b/arch/s390/kvm/priv.c @@ -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, };
diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c index 3584ed9b20a1..9e2b4705dea2 100644 --- a/arch/s390/mm/pgtable.c +++ b/arch/s390/mm/pgtable.c @@ -17,6 +17,7 @@ #include <linux/quicklist.h> #include <linux/rcupdate.h> #include <linux/slab.h> +#include <linux/swapops.h>
#include <asm/pgtable.h> #include <asm/pgalloc.h> @@ -594,6 +595,82 @@ unsigned long gmap_fault(unsigned long address, struct gmap *gmap) } EXPORT_SYMBOL_GPL(gmap_fault);
+static void gmap_zap_swap_entry(swp_entry_t entry, struct mm_struct *mm) +{ + if (!non_swap_entry(entry)) + dec_mm_counter(mm, MM_SWAPENTS); + else if (is_migration_entry(entry)) { + struct page *page = migration_entry_to_page(entry); + + if (PageAnon(page)) + dec_mm_counter(mm, MM_ANONPAGES); + else + dec_mm_counter(mm, MM_FILEPAGES); + } + free_swap_and_cache(entry); +} + +/** + * The mm->mmap_sem lock must be held + */ +static void gmap_zap_unused(struct mm_struct *mm, unsigned long address) +{ + unsigned long ptev, pgstev; + spinlock_t *ptl; + pgste_t pgste; + pte_t *ptep, pte; + + ptep = get_locked_pte(mm, address, &ptl); + if (unlikely(!ptep)) + return; + pte = *ptep; + if (!pte_swap(pte)) + goto out_pte; + /* Zap unused and logically-zero pages */ + pgste = pgste_get_lock(ptep); + pgstev = pgste_val(pgste); + ptev = pte_val(pte); + if (((pgstev & _PGSTE_GPS_USAGE_MASK) == _PGSTE_GPS_USAGE_UNUSED) || + ((pgstev & _PGSTE_GPS_ZERO) && (ptev & _PAGE_INVALID))) { + gmap_zap_swap_entry(pte_to_swp_entry(pte), mm); + pte_clear(mm, address, ptep); + } + pgste_set_unlock(ptep, pgste); +out_pte: + pte_unmap_unlock(*ptep, ptl); +} + +/* + * this function is assumed to be called with mmap_sem held + */ +void __gmap_zap(unsigned long address, struct gmap *gmap) +{ + unsigned long *table, *segment_ptr; + unsigned long segment, pgstev, ptev; + struct gmap_pgtable *mp; + struct page *page; + + segment_ptr = gmap_table_walk(address, gmap); + if (IS_ERR(segment_ptr)) + return; + segment = *segment_ptr; + if (segment & _SEGMENT_ENTRY_INVALID) + return; + page = pfn_to_page(segment >> PAGE_SHIFT); + mp = (struct gmap_pgtable *) page->index; + address = mp->vmaddr | (address & ~PMD_MASK); + /* Page table is present */ + table = (unsigned long *)(segment & _SEGMENT_ENTRY_ORIGIN); + table = table + ((address >> 12) & 0xff); + pgstev = table[PTRS_PER_PTE]; + ptev = table[0]; + /* quick check, checked again with locks held */ + if (((pgstev & _PGSTE_GPS_USAGE_MASK) == _PGSTE_GPS_USAGE_UNUSED) || + ((pgstev & _PGSTE_GPS_ZERO) && (ptev & _PAGE_INVALID))) + gmap_zap_unused(gmap->mm, address); +} +EXPORT_SYMBOL_GPL(__gmap_zap); + void gmap_discard(unsigned long from, unsigned long to, struct gmap *gmap) {