diff options
Diffstat (limited to 'arch/s390')
-rw-r--r-- | arch/s390/kvm/kvm-s390.c | 202 |
1 files changed, 201 insertions, 1 deletions
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index c2b391499374..e100a7ff35c7 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -30,8 +30,8 @@ #include <linux/vmalloc.h> #include <linux/bitmap.h> #include <linux/sched/signal.h> - #include <linux/string.h> + #include <asm/asm-offsets.h> #include <asm/lowcore.h> #include <asm/stp.h> @@ -387,6 +387,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) case KVM_CAP_S390_SKEYS: case KVM_CAP_S390_IRQ_STATE: case KVM_CAP_S390_USER_INSTR0: + case KVM_CAP_S390_CMMA_MIGRATION: case KVM_CAP_S390_AIS: r = 1; break; @@ -1419,6 +1420,182 @@ out: return r; } +/* + * Base address and length must be sent at the start of each block, therefore + * it's cheaper to send some clean data, as long as it's less than the size of + * two longs. + */ +#define KVM_S390_MAX_BIT_DISTANCE (2 * sizeof(void *)) +/* for consistency */ +#define KVM_S390_CMMA_SIZE_MAX ((u32)KVM_S390_SKEYS_MAX) + +/* + * This function searches for the next page with dirty CMMA attributes, and + * saves the attributes in the buffer up to either the end of the buffer or + * until a block of at least KVM_S390_MAX_BIT_DISTANCE clean bits is found; + * no trailing clean bytes are saved. + * In case no dirty bits were found, or if CMMA was not enabled or used, the + * output buffer will indicate 0 as length. + */ +static int kvm_s390_get_cmma_bits(struct kvm *kvm, + struct kvm_s390_cmma_log *args) +{ + struct kvm_s390_migration_state *s = kvm->arch.migration_state; + unsigned long bufsize, hva, pgstev, i, next, cur; + int srcu_idx, peek, r = 0, rr; + u8 *res; + + cur = args->start_gfn; + i = next = pgstev = 0; + + if (unlikely(!kvm->arch.use_cmma)) + return -ENXIO; + /* Invalid/unsupported flags were specified */ + if (args->flags & ~KVM_S390_CMMA_PEEK) + return -EINVAL; + /* Migration mode query, and we are not doing a migration */ + peek = !!(args->flags & KVM_S390_CMMA_PEEK); + if (!peek && !s) + return -EINVAL; + /* CMMA is disabled or was not used, or the buffer has length zero */ + bufsize = min(args->count, KVM_S390_CMMA_SIZE_MAX); + if (!bufsize || !kvm->mm->context.use_cmma) { + memset(args, 0, sizeof(*args)); + return 0; + } + + if (!peek) { + /* We are not peeking, and there are no dirty pages */ + if (!atomic64_read(&s->dirty_pages)) { + memset(args, 0, sizeof(*args)); + return 0; + } + cur = find_next_bit(s->pgste_bitmap, s->bitmap_size, + args->start_gfn); + if (cur >= s->bitmap_size) /* nothing found, loop back */ + cur = find_next_bit(s->pgste_bitmap, s->bitmap_size, 0); + if (cur >= s->bitmap_size) { /* again! (very unlikely) */ + memset(args, 0, sizeof(*args)); + return 0; + } + next = find_next_bit(s->pgste_bitmap, s->bitmap_size, cur + 1); + } + + res = vmalloc(bufsize); + if (!res) + return -ENOMEM; + + args->start_gfn = cur; + + down_read(&kvm->mm->mmap_sem); + srcu_idx = srcu_read_lock(&kvm->srcu); + while (i < bufsize) { + hva = gfn_to_hva(kvm, cur); + if (kvm_is_error_hva(hva)) { + r = -EFAULT; + break; + } + /* decrement only if we actually flipped the bit to 0 */ + if (!peek && test_and_clear_bit(cur, s->pgste_bitmap)) + atomic64_dec(&s->dirty_pages); + r = get_pgste(kvm->mm, hva, &pgstev); + if (r < 0) + pgstev = 0; + /* save the value */ + res[i++] = (pgstev >> 24) & 0x3; + /* + * if the next bit is too far away, stop. + * if we reached the previous "next", find the next one + */ + if (!peek) { + if (next > cur + KVM_S390_MAX_BIT_DISTANCE) + break; + if (cur == next) + next = find_next_bit(s->pgste_bitmap, + s->bitmap_size, cur + 1); + /* reached the end of the bitmap or of the buffer, stop */ + if ((next >= s->bitmap_size) || + (next >= args->start_gfn + bufsize)) + break; + } + cur++; + } + srcu_read_unlock(&kvm->srcu, srcu_idx); + up_read(&kvm->mm->mmap_sem); + args->count = i; + args->remaining = s ? atomic64_read(&s->dirty_pages) : 0; + + rr = copy_to_user((void __user *)args->values, res, args->count); + if (rr) + r = -EFAULT; + + vfree(res); + return r; +} + +/* + * This function sets the CMMA attributes for the given pages. If the input + * buffer has zero length, no action is taken, otherwise the attributes are + * set and the mm->context.use_cmma flag is set. + */ +static int kvm_s390_set_cmma_bits(struct kvm *kvm, + const struct kvm_s390_cmma_log *args) +{ + unsigned long hva, mask, pgstev, i; + uint8_t *bits; + int srcu_idx, r = 0; + + mask = args->mask; + + if (!kvm->arch.use_cmma) + return -ENXIO; + /* invalid/unsupported flags */ + if (args->flags != 0) + return -EINVAL; + /* Enforce sane limit on memory allocation */ + if (args->count > KVM_S390_CMMA_SIZE_MAX) + return -EINVAL; + /* Nothing to do */ + if (args->count == 0) + return 0; + + bits = vmalloc(sizeof(*bits) * args->count); + if (!bits) + return -ENOMEM; + + r = copy_from_user(bits, (void __user *)args->values, args->count); + if (r) { + r = -EFAULT; + goto out; + } + + down_read(&kvm->mm->mmap_sem); + srcu_idx = srcu_read_lock(&kvm->srcu); + for (i = 0; i < args->count; i++) { + hva = gfn_to_hva(kvm, args->start_gfn + i); + if (kvm_is_error_hva(hva)) { + r = -EFAULT; + break; + } + + pgstev = bits[i]; + pgstev = pgstev << 24; + mask &= _PGSTE_GPS_USAGE_MASK; + set_pgste_bits(kvm->mm, hva, mask, pgstev); + } + srcu_read_unlock(&kvm->srcu, srcu_idx); + up_read(&kvm->mm->mmap_sem); + + if (!kvm->mm->context.use_cmma) { + down_write(&kvm->mm->mmap_sem); + kvm->mm->context.use_cmma = 1; + up_write(&kvm->mm->mmap_sem); + } +out: + vfree(bits); + return r; +} + long kvm_arch_vm_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg) { @@ -1497,6 +1674,29 @@ long kvm_arch_vm_ioctl(struct file *filp, r = kvm_s390_set_skeys(kvm, &args); break; } + case KVM_S390_GET_CMMA_BITS: { + struct kvm_s390_cmma_log args; + + r = -EFAULT; + if (copy_from_user(&args, argp, sizeof(args))) + break; + r = kvm_s390_get_cmma_bits(kvm, &args); + if (!r) { + r = copy_to_user(argp, &args, sizeof(args)); + if (r) + r = -EFAULT; + } + break; + } + case KVM_S390_SET_CMMA_BITS: { + struct kvm_s390_cmma_log args; + + r = -EFAULT; + if (copy_from_user(&args, argp, sizeof(args))) + break; + r = kvm_s390_set_cmma_bits(kvm, &args); + break; + } default: r = -ENOTTY; } |