| Message ID | 20221025151344.3784230-9-chao.p.peng@linux.intel.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | KVM: mm: fd-based approach for supporting KVM | expand |
Hi, On Tue, Oct 25, 2022 at 4:20 PM Chao Peng <chao.p.peng@linux.intel.com> wrote: > > Expose KVM_MEM_PRIVATE and memslot fields restricted_fd/offset to > userspace. KVM register/unregister private memslot to fd-based > memory backing store and responses to invalidation event from > restrictedmem_notifier to zap the existing memory mappings in the > secondary page table. > > Whether KVM_MEM_PRIVATE is actually exposed to userspace is determined > by architecture code which can turn on it by overriding the default > kvm_arch_has_private_mem(). > > A 'kvm' reference is added in memslot structure since in > restrictedmem_notifier callback we can only obtain a memslot reference > but 'kvm' is needed to do the zapping. > > Co-developed-by: Yu Zhang <yu.c.zhang@linux.intel.com> > Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com> > Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com> > --- > include/linux/kvm_host.h | 3 +- > virt/kvm/kvm_main.c | 174 +++++++++++++++++++++++++++++++++++++-- > 2 files changed, 171 insertions(+), 6 deletions(-) Reviewed-by: Fuad Tabba <tabba@google.com> Thanks, /fuad > > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > index 69300fc6d572..e27d62c30484 100644 > --- a/include/linux/kvm_host.h > +++ b/include/linux/kvm_host.h > @@ -246,7 +246,7 @@ int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu); > #endif > > > -#if defined(KVM_ARCH_WANT_MMU_NOTIFIER) || defined(CONFIG_KVM_GENERIC_PRIVATE_MEM) > +#if defined(KVM_ARCH_WANT_MMU_NOTIFIER) || defined(CONFIG_HAVE_KVM_RESTRICTED_MEM) > struct kvm_gfn_range { > struct kvm_memory_slot *slot; > gfn_t start; > @@ -583,6 +583,7 @@ struct kvm_memory_slot { > struct file *restricted_file; > loff_t restricted_offset; > struct restrictedmem_notifier notifier; > + struct kvm *kvm; > }; > > static inline bool kvm_slot_can_be_private(const struct kvm_memory_slot *slot) > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 13a37b4d9e97..dae6a2c196ad 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -1028,6 +1028,111 @@ static int kvm_vm_ioctl_set_mem_attr(struct kvm *kvm, gpa_t gpa, gpa_t size, > } > #endif /* CONFIG_KVM_GENERIC_PRIVATE_MEM */ > > +#ifdef CONFIG_HAVE_KVM_RESTRICTED_MEM > +static bool restrictedmem_range_is_valid(struct kvm_memory_slot *slot, > + pgoff_t start, pgoff_t end, > + gfn_t *gfn_start, gfn_t *gfn_end) > +{ > + unsigned long base_pgoff = slot->restricted_offset >> PAGE_SHIFT; > + > + if (start > base_pgoff) > + *gfn_start = slot->base_gfn + start - base_pgoff; > + else > + *gfn_start = slot->base_gfn; > + > + if (end < base_pgoff + slot->npages) > + *gfn_end = slot->base_gfn + end - base_pgoff; > + else > + *gfn_end = slot->base_gfn + slot->npages; > + > + if (*gfn_start >= *gfn_end) > + return false; > + > + return true; > +} > + > +static void kvm_restrictedmem_invalidate_begin(struct restrictedmem_notifier *notifier, > + pgoff_t start, pgoff_t end) > +{ > + struct kvm_memory_slot *slot = container_of(notifier, > + struct kvm_memory_slot, > + notifier); > + struct kvm *kvm = slot->kvm; > + gfn_t gfn_start, gfn_end; > + struct kvm_gfn_range gfn_range; > + int idx; > + > + if (!restrictedmem_range_is_valid(slot, start, end, > + &gfn_start, &gfn_end)) > + return; > + > + idx = srcu_read_lock(&kvm->srcu); > + KVM_MMU_LOCK(kvm); > + > + kvm_mmu_invalidate_begin(kvm, gfn_start, gfn_end); > + > + gfn_range.start = gfn_start; > + gfn_range.end = gfn_end; > + gfn_range.slot = slot; > + gfn_range.pte = __pte(0); > + gfn_range.may_block = true; > + > + if (kvm_unmap_gfn_range(kvm, &gfn_range)) > + kvm_flush_remote_tlbs(kvm); > + > + KVM_MMU_UNLOCK(kvm); > + srcu_read_unlock(&kvm->srcu, idx); > +} > + > +static void kvm_restrictedmem_invalidate_end(struct restrictedmem_notifier *notifier, > + pgoff_t start, pgoff_t end) > +{ > + struct kvm_memory_slot *slot = container_of(notifier, > + struct kvm_memory_slot, > + notifier); > + struct kvm *kvm = slot->kvm; > + gfn_t gfn_start, gfn_end; > + > + if (!restrictedmem_range_is_valid(slot, start, end, > + &gfn_start, &gfn_end)) > + return; > + > + KVM_MMU_LOCK(kvm); > + kvm_mmu_invalidate_end(kvm, gfn_start, gfn_end); > + KVM_MMU_UNLOCK(kvm); > +} > + > +static struct restrictedmem_notifier_ops kvm_restrictedmem_notifier_ops = { > + .invalidate_start = kvm_restrictedmem_invalidate_begin, > + .invalidate_end = kvm_restrictedmem_invalidate_end, > +}; > + > +static inline void kvm_restrictedmem_register(struct kvm_memory_slot *slot) > +{ > + slot->notifier.ops = &kvm_restrictedmem_notifier_ops; > + restrictedmem_register_notifier(slot->restricted_file, &slot->notifier); > +} > + > +static inline void kvm_restrictedmem_unregister(struct kvm_memory_slot *slot) > +{ > + restrictedmem_unregister_notifier(slot->restricted_file, > + &slot->notifier); > +} > + > +#else /* !CONFIG_HAVE_KVM_RESTRICTED_MEM */ > + > +static inline void kvm_restrictedmem_register(struct kvm_memory_slot *slot) > +{ > + WARN_ON_ONCE(1); > +} > + > +static inline void kvm_restrictedmem_unregister(struct kvm_memory_slot *slot) > +{ > + WARN_ON_ONCE(1); > +} > + > +#endif /* CONFIG_HAVE_KVM_RESTRICTED_MEM */ > + > #ifdef CONFIG_HAVE_KVM_PM_NOTIFIER > static int kvm_pm_notifier_call(struct notifier_block *bl, > unsigned long state, > @@ -1072,6 +1177,11 @@ static void kvm_destroy_dirty_bitmap(struct kvm_memory_slot *memslot) > /* This does not remove the slot from struct kvm_memslots data structures */ > static void kvm_free_memslot(struct kvm *kvm, struct kvm_memory_slot *slot) > { > + if (slot->flags & KVM_MEM_PRIVATE) { > + kvm_restrictedmem_unregister(slot); > + fput(slot->restricted_file); > + } > + > kvm_destroy_dirty_bitmap(slot); > > kvm_arch_free_memslot(kvm, slot); > @@ -1643,10 +1753,16 @@ bool __weak kvm_arch_has_private_mem(struct kvm *kvm) > return false; > } > > -static int check_memory_region_flags(const struct kvm_user_mem_region *mem) > +static int check_memory_region_flags(struct kvm *kvm, > + const struct kvm_user_mem_region *mem) > { > u32 valid_flags = KVM_MEM_LOG_DIRTY_PAGES; > > +#ifdef CONFIG_KVM_GENERIC_PRIVATE_MEM > + if (kvm_arch_has_private_mem(kvm)) > + valid_flags |= KVM_MEM_PRIVATE; > +#endif > + > #ifdef __KVM_HAVE_READONLY_MEM > valid_flags |= KVM_MEM_READONLY; > #endif > @@ -1722,6 +1838,9 @@ static int kvm_prepare_memory_region(struct kvm *kvm, > { > int r; > > + if (change == KVM_MR_CREATE && new->flags & KVM_MEM_PRIVATE) > + kvm_restrictedmem_register(new); > + > /* > * If dirty logging is disabled, nullify the bitmap; the old bitmap > * will be freed on "commit". If logging is enabled in both old and > @@ -1750,6 +1869,9 @@ static int kvm_prepare_memory_region(struct kvm *kvm, > if (r && new && new->dirty_bitmap && (!old || !old->dirty_bitmap)) > kvm_destroy_dirty_bitmap(new); > > + if (r && change == KVM_MR_CREATE && new->flags & KVM_MEM_PRIVATE) > + kvm_restrictedmem_unregister(new); > + > return r; > } > > @@ -2047,7 +2169,7 @@ int __kvm_set_memory_region(struct kvm *kvm, > int as_id, id; > int r; > > - r = check_memory_region_flags(mem); > + r = check_memory_region_flags(kvm, mem); > if (r) > return r; > > @@ -2066,6 +2188,10 @@ int __kvm_set_memory_region(struct kvm *kvm, > !access_ok((void __user *)(unsigned long)mem->userspace_addr, > mem->memory_size)) > return -EINVAL; > + if (mem->flags & KVM_MEM_PRIVATE && > + (mem->restricted_offset & (PAGE_SIZE - 1) || > + mem->restricted_offset > U64_MAX - mem->memory_size)) > + return -EINVAL; > if (as_id >= KVM_ADDRESS_SPACE_NUM || id >= KVM_MEM_SLOTS_NUM) > return -EINVAL; > if (mem->guest_phys_addr + mem->memory_size < mem->guest_phys_addr) > @@ -2104,6 +2230,9 @@ int __kvm_set_memory_region(struct kvm *kvm, > if ((kvm->nr_memslot_pages + npages) < kvm->nr_memslot_pages) > return -EINVAL; > } else { /* Modify an existing slot. */ > + /* Private memslots are immutable, they can only be deleted. */ > + if (mem->flags & KVM_MEM_PRIVATE) > + return -EINVAL; > if ((mem->userspace_addr != old->userspace_addr) || > (npages != old->npages) || > ((mem->flags ^ old->flags) & KVM_MEM_READONLY)) > @@ -2132,10 +2261,28 @@ int __kvm_set_memory_region(struct kvm *kvm, > new->npages = npages; > new->flags = mem->flags; > new->userspace_addr = mem->userspace_addr; > + if (mem->flags & KVM_MEM_PRIVATE) { > + new->restricted_file = fget(mem->restricted_fd); > + if (!new->restricted_file || > + !file_is_restrictedmem(new->restricted_file)) { > + r = -EINVAL; > + goto out; > + } > + new->restricted_offset = mem->restricted_offset; > + } > + > + new->kvm = kvm; > > r = kvm_set_memslot(kvm, old, new, change); > if (r) > - kfree(new); > + goto out; > + > + return 0; > + > +out: > + if (new->restricted_file) > + fput(new->restricted_file); > + kfree(new); > return r; > } > EXPORT_SYMBOL_GPL(__kvm_set_memory_region); > @@ -4604,6 +4751,11 @@ static long kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg) > case KVM_CAP_BINARY_STATS_FD: > case KVM_CAP_SYSTEM_EVENT_DATA: > return 1; > +#ifdef CONFIG_KVM_GENERIC_PRIVATE_MEM > + case KVM_CAP_PRIVATE_MEM: > + return 1; > +#endif > + > default: > break; > } > @@ -4795,16 +4947,28 @@ static long kvm_vm_ioctl(struct file *filp, > } > case KVM_SET_USER_MEMORY_REGION: { > struct kvm_user_mem_region mem; > - unsigned long size = sizeof(struct kvm_userspace_memory_region); > + unsigned int flags_offset = offsetof(typeof(mem), flags); > + unsigned long size; > + u32 flags; > > kvm_sanity_check_user_mem_region_alias(); > > + memset(&mem, 0, sizeof(mem)); > + > r = -EFAULT; > + if (get_user(flags, (u32 __user *)(argp + flags_offset))) > + goto out; > + > + if (flags & KVM_MEM_PRIVATE) > + size = sizeof(struct kvm_userspace_memory_region_ext); > + else > + size = sizeof(struct kvm_userspace_memory_region); > + > if (copy_from_user(&mem, argp, size)) > goto out; > > r = -EINVAL; > - if (mem.flags & KVM_MEM_PRIVATE) > + if ((flags ^ mem.flags) & KVM_MEM_PRIVATE) > goto out; > > r = kvm_vm_ioctl_set_memory_region(kvm, &mem); > -- > 2.25.1 >
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 69300fc6d572..e27d62c30484 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -246,7 +246,7 @@ int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu); #endif -#if defined(KVM_ARCH_WANT_MMU_NOTIFIER) || defined(CONFIG_KVM_GENERIC_PRIVATE_MEM) +#if defined(KVM_ARCH_WANT_MMU_NOTIFIER) || defined(CONFIG_HAVE_KVM_RESTRICTED_MEM) struct kvm_gfn_range { struct kvm_memory_slot *slot; gfn_t start; @@ -583,6 +583,7 @@ struct kvm_memory_slot { struct file *restricted_file; loff_t restricted_offset; struct restrictedmem_notifier notifier; + struct kvm *kvm; }; static inline bool kvm_slot_can_be_private(const struct kvm_memory_slot *slot) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 13a37b4d9e97..dae6a2c196ad 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1028,6 +1028,111 @@ static int kvm_vm_ioctl_set_mem_attr(struct kvm *kvm, gpa_t gpa, gpa_t size, } #endif /* CONFIG_KVM_GENERIC_PRIVATE_MEM */ +#ifdef CONFIG_HAVE_KVM_RESTRICTED_MEM +static bool restrictedmem_range_is_valid(struct kvm_memory_slot *slot, + pgoff_t start, pgoff_t end, + gfn_t *gfn_start, gfn_t *gfn_end) +{ + unsigned long base_pgoff = slot->restricted_offset >> PAGE_SHIFT; + + if (start > base_pgoff) + *gfn_start = slot->base_gfn + start - base_pgoff; + else + *gfn_start = slot->base_gfn; + + if (end < base_pgoff + slot->npages) + *gfn_end = slot->base_gfn + end - base_pgoff; + else + *gfn_end = slot->base_gfn + slot->npages; + + if (*gfn_start >= *gfn_end) + return false; + + return true; +} + +static void kvm_restrictedmem_invalidate_begin(struct restrictedmem_notifier *notifier, + pgoff_t start, pgoff_t end) +{ + struct kvm_memory_slot *slot = container_of(notifier, + struct kvm_memory_slot, + notifier); + struct kvm *kvm = slot->kvm; + gfn_t gfn_start, gfn_end; + struct kvm_gfn_range gfn_range; + int idx; + + if (!restrictedmem_range_is_valid(slot, start, end, + &gfn_start, &gfn_end)) + return; + + idx = srcu_read_lock(&kvm->srcu); + KVM_MMU_LOCK(kvm); + + kvm_mmu_invalidate_begin(kvm, gfn_start, gfn_end); + + gfn_range.start = gfn_start; + gfn_range.end = gfn_end; + gfn_range.slot = slot; + gfn_range.pte = __pte(0); + gfn_range.may_block = true; + + if (kvm_unmap_gfn_range(kvm, &gfn_range)) + kvm_flush_remote_tlbs(kvm); + + KVM_MMU_UNLOCK(kvm); + srcu_read_unlock(&kvm->srcu, idx); +} + +static void kvm_restrictedmem_invalidate_end(struct restrictedmem_notifier *notifier, + pgoff_t start, pgoff_t end) +{ + struct kvm_memory_slot *slot = container_of(notifier, + struct kvm_memory_slot, + notifier); + struct kvm *kvm = slot->kvm; + gfn_t gfn_start, gfn_end; + + if (!restrictedmem_range_is_valid(slot, start, end, + &gfn_start, &gfn_end)) + return; + + KVM_MMU_LOCK(kvm); + kvm_mmu_invalidate_end(kvm, gfn_start, gfn_end); + KVM_MMU_UNLOCK(kvm); +} + +static struct restrictedmem_notifier_ops kvm_restrictedmem_notifier_ops = { + .invalidate_start = kvm_restrictedmem_invalidate_begin, + .invalidate_end = kvm_restrictedmem_invalidate_end, +}; + +static inline void kvm_restrictedmem_register(struct kvm_memory_slot *slot) +{ + slot->notifier.ops = &kvm_restrictedmem_notifier_ops; + restrictedmem_register_notifier(slot->restricted_file, &slot->notifier); +} + +static inline void kvm_restrictedmem_unregister(struct kvm_memory_slot *slot) +{ + restrictedmem_unregister_notifier(slot->restricted_file, + &slot->notifier); +} + +#else /* !CONFIG_HAVE_KVM_RESTRICTED_MEM */ + +static inline void kvm_restrictedmem_register(struct kvm_memory_slot *slot) +{ + WARN_ON_ONCE(1); +} + +static inline void kvm_restrictedmem_unregister(struct kvm_memory_slot *slot) +{ + WARN_ON_ONCE(1); +} + +#endif /* CONFIG_HAVE_KVM_RESTRICTED_MEM */ + #ifdef CONFIG_HAVE_KVM_PM_NOTIFIER static int kvm_pm_notifier_call(struct notifier_block *bl, unsigned long state, @@ -1072,6 +1177,11 @@ static void kvm_destroy_dirty_bitmap(struct kvm_memory_slot *memslot) /* This does not remove the slot from struct kvm_memslots data structures */ static void kvm_free_memslot(struct kvm *kvm, struct kvm_memory_slot *slot) { + if (slot->flags & KVM_MEM_PRIVATE) { + kvm_restrictedmem_unregister(slot); + fput(slot->restricted_file); + } + kvm_destroy_dirty_bitmap(slot); kvm_arch_free_memslot(kvm, slot); @@ -1643,10 +1753,16 @@ bool __weak kvm_arch_has_private_mem(struct kvm *kvm) return false; } -static int check_memory_region_flags(const struct kvm_user_mem_region *mem) +static int check_memory_region_flags(struct kvm *kvm, + const struct kvm_user_mem_region *mem) { u32 valid_flags = KVM_MEM_LOG_DIRTY_PAGES; +#ifdef CONFIG_KVM_GENERIC_PRIVATE_MEM + if (kvm_arch_has_private_mem(kvm)) + valid_flags |= KVM_MEM_PRIVATE; +#endif + #ifdef __KVM_HAVE_READONLY_MEM valid_flags |= KVM_MEM_READONLY; #endif @@ -1722,6 +1838,9 @@ static int kvm_prepare_memory_region(struct kvm *kvm, { int r; + if (change == KVM_MR_CREATE && new->flags & KVM_MEM_PRIVATE) + kvm_restrictedmem_register(new); + /* * If dirty logging is disabled, nullify the bitmap; the old bitmap * will be freed on "commit". If logging is enabled in both old and @@ -1750,6 +1869,9 @@ static int kvm_prepare_memory_region(struct kvm *kvm, if (r && new && new->dirty_bitmap && (!old || !old->dirty_bitmap)) kvm_destroy_dirty_bitmap(new); + if (r && change == KVM_MR_CREATE && new->flags & KVM_MEM_PRIVATE) + kvm_restrictedmem_unregister(new); + return r; } @@ -2047,7 +2169,7 @@ int __kvm_set_memory_region(struct kvm *kvm, int as_id, id; int r; - r = check_memory_region_flags(mem); + r = check_memory_region_flags(kvm, mem); if (r) return r; @@ -2066,6 +2188,10 @@ int __kvm_set_memory_region(struct kvm *kvm, !access_ok((void __user *)(unsigned long)mem->userspace_addr, mem->memory_size)) return -EINVAL; + if (mem->flags & KVM_MEM_PRIVATE && + (mem->restricted_offset & (PAGE_SIZE - 1) || + mem->restricted_offset > U64_MAX - mem->memory_size)) + return -EINVAL; if (as_id >= KVM_ADDRESS_SPACE_NUM || id >= KVM_MEM_SLOTS_NUM) return -EINVAL; if (mem->guest_phys_addr + mem->memory_size < mem->guest_phys_addr) @@ -2104,6 +2230,9 @@ int __kvm_set_memory_region(struct kvm *kvm, if ((kvm->nr_memslot_pages + npages) < kvm->nr_memslot_pages) return -EINVAL; } else { /* Modify an existing slot. */ + /* Private memslots are immutable, they can only be deleted. */ + if (mem->flags & KVM_MEM_PRIVATE) + return -EINVAL; if ((mem->userspace_addr != old->userspace_addr) || (npages != old->npages) || ((mem->flags ^ old->flags) & KVM_MEM_READONLY)) @@ -2132,10 +2261,28 @@ int __kvm_set_memory_region(struct kvm *kvm, new->npages = npages; new->flags = mem->flags; new->userspace_addr = mem->userspace_addr; + if (mem->flags & KVM_MEM_PRIVATE) { + new->restricted_file = fget(mem->restricted_fd); + if (!new->restricted_file || + !file_is_restrictedmem(new->restricted_file)) { + r = -EINVAL; + goto out; + } + new->restricted_offset = mem->restricted_offset; + } + + new->kvm = kvm; r = kvm_set_memslot(kvm, old, new, change); if (r) - kfree(new); + goto out; + + return 0; + +out: + if (new->restricted_file) + fput(new->restricted_file); + kfree(new); return r; } EXPORT_SYMBOL_GPL(__kvm_set_memory_region); @@ -4604,6 +4751,11 @@ static long kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg) case KVM_CAP_BINARY_STATS_FD: case KVM_CAP_SYSTEM_EVENT_DATA: return 1; +#ifdef CONFIG_KVM_GENERIC_PRIVATE_MEM + case KVM_CAP_PRIVATE_MEM: + return 1; +#endif + default: break; } @@ -4795,16 +4947,28 @@ static long kvm_vm_ioctl(struct file *filp, } case KVM_SET_USER_MEMORY_REGION: { struct kvm_user_mem_region mem; - unsigned long size = sizeof(struct kvm_userspace_memory_region); + unsigned int flags_offset = offsetof(typeof(mem), flags); + unsigned long size; + u32 flags; kvm_sanity_check_user_mem_region_alias(); + memset(&mem, 0, sizeof(mem)); + r = -EFAULT; + if (get_user(flags, (u32 __user *)(argp + flags_offset))) + goto out; + + if (flags & KVM_MEM_PRIVATE) + size = sizeof(struct kvm_userspace_memory_region_ext); + else + size = sizeof(struct kvm_userspace_memory_region); + if (copy_from_user(&mem, argp, size)) goto out; r = -EINVAL; - if (mem.flags & KVM_MEM_PRIVATE) + if ((flags ^ mem.flags) & KVM_MEM_PRIVATE) goto out; r = kvm_vm_ioctl_set_memory_region(kvm, &mem);