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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>
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konne88 authored and Martin Schwidefsky committed Apr 17, 2013
1 parent 4596172 commit b31288fa83b2bcc8834e1e208e9526b8bd5ce361
@@ -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;
@@ -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);
}
View
@@ -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;
View
@@ -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);
View
@@ -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,
};
View
@@ -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)
{

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