| Message ID | 20231105163040.14904-9-pbonzini@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: guest_memfd() and per-page attributes | expand |
> > diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst > index 7025b3751027..bdea1423c5f8 100644 > --- a/Documentation/virt/kvm/api.rst > +++ b/Documentation/virt/kvm/api.rst > @@ -1340,6 +1340,7 @@ yet and must be cleared on entry. > __u64 guest_phys_addr; > __u64 memory_size; /* bytes */ > __u64 userspace_addr; /* start of the userspace allocated memory */ > + __u64 pad[16]; Looks this "pad[16]" should be moved to ... > }; > > /* for kvm_userspace_memory_region::flags */ > @@ -6192,6 +6193,27 @@ to know what fields can be changed for the system register described by > ``op0, op1, crn, crm, op2``. KVM rejects ID register values that describe a > superset of the features supported by the system. > > +4.140 KVM_SET_USER_MEMORY_REGION2 > +--------------------------------- > + > +:Capability: KVM_CAP_USER_MEMORY2 > +:Architectures: all > +:Type: vm ioctl > +:Parameters: struct kvm_userspace_memory_region2 (in) > +:Returns: 0 on success, -1 on error > + > +:: > + > + struct kvm_userspace_memory_region2 { > + __u32 slot; > + __u32 flags; > + __u64 guest_phys_addr; > + __u64 memory_size; /* bytes */ > + __u64 userspace_addr; /* start of the userspace allocated memory */ > + }; > + ... here. Acked-by: Kai Huang <kai.huang@intel.com>
On Sun, Nov 05, 2023 at 05:30:11PM +0100, Paolo Bonzini wrote: > From: Sean Christopherson <seanjc@google.com> > > Introduce a "version 2" of KVM_SET_USER_MEMORY_REGION so that additional > information can be supplied without setting userspace up to fail. The > padding in the new kvm_userspace_memory_region2 structure will be used to > pass a file descriptor in addition to the userspace_addr, i.e. allow > userspace to point at a file descriptor and map memory into a guest that > is NOT mapped into host userspace. > > Alternatively, KVM could simply add "struct kvm_userspace_memory_region2" > without a new ioctl(), but as Paolo pointed out, adding a new ioctl() > makes detection of bad flags a bit more robust, e.g. if the new fd field > is guarded only by a flag and not a new ioctl(), then a userspace bug > (setting a "bad" flag) would generate out-of-bounds access instead of an > -EINVAL error. > > Cc: Jarkko Sakkinen <jarkko@kernel.org> > Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> > Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com> > Signed-off-by: Sean Christopherson <seanjc@google.com> > Reviewed-by: Fuad Tabba <tabba@google.com> > Tested-by: Fuad Tabba <tabba@google.com> > Message-Id: <20231027182217.3615211-9-seanjc@google.com> > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> > --- > Documentation/virt/kvm/api.rst | 22 +++++++++++++ > arch/x86/kvm/x86.c | 2 +- > include/linux/kvm_host.h | 4 +-- > include/uapi/linux/kvm.h | 13 ++++++++ > virt/kvm/kvm_main.c | 57 +++++++++++++++++++++++++++++----- > 5 files changed, 87 insertions(+), 11 deletions(-) > > diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst > index 7025b3751027..bdea1423c5f8 100644 > --- a/Documentation/virt/kvm/api.rst > +++ b/Documentation/virt/kvm/api.rst > @@ -1340,6 +1340,7 @@ yet and must be cleared on entry. > __u64 guest_phys_addr; > __u64 memory_size; /* bytes */ > __u64 userspace_addr; /* start of the userspace allocated memory */ > + __u64 pad[16]; Looks incorrect to add padding part in kvm_userspace_memory_region, only need to apply on kvm_userspace_memory_region2 below. > }; > > /* for kvm_userspace_memory_region::flags */ > @@ -6192,6 +6193,27 @@ to know what fields can be changed for the system register described by > ``op0, op1, crn, crm, op2``. KVM rejects ID register values that describe a > superset of the features supported by the system. > > +4.140 KVM_SET_USER_MEMORY_REGION2 > +--------------------------------- > + > +:Capability: KVM_CAP_USER_MEMORY2 > +:Architectures: all > +:Type: vm ioctl > +:Parameters: struct kvm_userspace_memory_region2 (in) > +:Returns: 0 on success, -1 on error > + > +:: > + > + struct kvm_userspace_memory_region2 { > + __u32 slot; > + __u32 flags; > + __u64 guest_phys_addr; > + __u64 memory_size; /* bytes */ > + __u64 userspace_addr; /* start of the userspace allocated memory */ > + }; > + > +See KVM_SET_USER_MEMORY_REGION. > + > 5. The kvm_run structure > ======================== > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 2c924075f6f1..7b389f27dffc 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -12576,7 +12576,7 @@ void __user * __x86_set_memory_region(struct kvm *kvm, int id, gpa_t gpa, > } > > for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) { > - struct kvm_userspace_memory_region m; > + struct kvm_userspace_memory_region2 m; > > m.slot = id | (i << 16); > m.flags = 0; > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > index 5faba69403ac..4e741ff27af3 100644 > --- a/include/linux/kvm_host.h > +++ b/include/linux/kvm_host.h > @@ -1146,9 +1146,9 @@ enum kvm_mr_change { > }; > > int kvm_set_memory_region(struct kvm *kvm, > - const struct kvm_userspace_memory_region *mem); > + const struct kvm_userspace_memory_region2 *mem); > int __kvm_set_memory_region(struct kvm *kvm, > - const struct kvm_userspace_memory_region *mem); > + const struct kvm_userspace_memory_region2 *mem); > void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *slot); > void kvm_arch_memslots_updated(struct kvm *kvm, u64 gen); > int kvm_arch_prepare_memory_region(struct kvm *kvm, > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h > index 211b86de35ac..308cc70bd6ab 100644 > --- a/include/uapi/linux/kvm.h > +++ b/include/uapi/linux/kvm.h > @@ -95,6 +95,16 @@ struct kvm_userspace_memory_region { > __u64 userspace_addr; /* start of the userspace allocated memory */ > }; > > +/* for KVM_SET_USER_MEMORY_REGION2 */ > +struct kvm_userspace_memory_region2 { > + __u32 slot; > + __u32 flags; > + __u64 guest_phys_addr; > + __u64 memory_size; > + __u64 userspace_addr; > + __u64 pad[16]; > +}; > + > /* > * The bit 0 ~ bit 15 of kvm_userspace_memory_region::flags are visible for > * userspace, other bits are reserved for kvm internal use which are defined > @@ -1201,6 +1211,7 @@ struct kvm_ppc_resize_hpt { > #define KVM_CAP_ARM_EAGER_SPLIT_CHUNK_SIZE 228 > #define KVM_CAP_ARM_SUPPORTED_BLOCK_SIZES 229 > #define KVM_CAP_ARM_SUPPORTED_REG_MASK_RANGES 230 > +#define KVM_CAP_USER_MEMORY2 231 > > #ifdef KVM_CAP_IRQ_ROUTING > > @@ -1483,6 +1494,8 @@ struct kvm_vfio_spapr_tce { > struct kvm_userspace_memory_region) > #define KVM_SET_TSS_ADDR _IO(KVMIO, 0x47) > #define KVM_SET_IDENTITY_MAP_ADDR _IOW(KVMIO, 0x48, __u64) > +#define KVM_SET_USER_MEMORY_REGION2 _IOW(KVMIO, 0x49, \ > + struct kvm_userspace_memory_region2) > > /* enable ucontrol for s390 */ > struct kvm_s390_ucas_mapping { > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index dc81279ea385..756b94ecd511 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -1580,7 +1580,15 @@ static void kvm_replace_memslot(struct kvm *kvm, > } > } > > -static int check_memory_region_flags(const struct kvm_userspace_memory_region *mem) > +/* > + * Flags that do not access any of the extra space of struct > + * kvm_userspace_memory_region2. KVM_SET_USER_MEMORY_REGION_V1_FLAGS > + * only allows these. > + */ > +#define KVM_SET_USER_MEMORY_REGION_V1_FLAGS \ > + (KVM_MEM_LOG_DIRTY_PAGES | KVM_MEM_READONLY) > + > +static int check_memory_region_flags(const struct kvm_userspace_memory_region2 *mem) > { > u32 valid_flags = KVM_MEM_LOG_DIRTY_PAGES; > > @@ -1982,7 +1990,7 @@ static bool kvm_check_memslot_overlap(struct kvm_memslots *slots, int id, > * Must be called holding kvm->slots_lock for write. > */ > int __kvm_set_memory_region(struct kvm *kvm, > - const struct kvm_userspace_memory_region *mem) > + const struct kvm_userspace_memory_region2 *mem) > { > struct kvm_memory_slot *old, *new; > struct kvm_memslots *slots; > @@ -2086,7 +2094,7 @@ int __kvm_set_memory_region(struct kvm *kvm, > EXPORT_SYMBOL_GPL(__kvm_set_memory_region); > > int kvm_set_memory_region(struct kvm *kvm, > - const struct kvm_userspace_memory_region *mem) > + const struct kvm_userspace_memory_region2 *mem) > { > int r; > > @@ -2098,7 +2106,7 @@ int kvm_set_memory_region(struct kvm *kvm, > EXPORT_SYMBOL_GPL(kvm_set_memory_region); > > static int kvm_vm_ioctl_set_memory_region(struct kvm *kvm, > - struct kvm_userspace_memory_region *mem) > + struct kvm_userspace_memory_region2 *mem) > { > if ((u16)mem->slot >= KVM_USER_MEM_SLOTS) > return -EINVAL; > @@ -4568,6 +4576,7 @@ static int kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg) > { > switch (arg) { > case KVM_CAP_USER_MEMORY: > + case KVM_CAP_USER_MEMORY2: > case KVM_CAP_DESTROY_MEMORY_REGION_WORKS: > case KVM_CAP_JOIN_MEMORY_REGIONS_WORKS: > case KVM_CAP_INTERNAL_ERROR_DATA: > @@ -4823,6 +4832,14 @@ static int kvm_vm_ioctl_get_stats_fd(struct kvm *kvm) > return fd; > } > > +#define SANITY_CHECK_MEM_REGION_FIELD(field) \ > +do { \ > + BUILD_BUG_ON(offsetof(struct kvm_userspace_memory_region, field) != \ > + offsetof(struct kvm_userspace_memory_region2, field)); \ > + BUILD_BUG_ON(sizeof_field(struct kvm_userspace_memory_region, field) != \ > + sizeof_field(struct kvm_userspace_memory_region2, field)); \ > +} while (0) > + > static long kvm_vm_ioctl(struct file *filp, > unsigned int ioctl, unsigned long arg) > { > @@ -4845,15 +4862,39 @@ static long kvm_vm_ioctl(struct file *filp, > r = kvm_vm_ioctl_enable_cap_generic(kvm, &cap); > break; > } > + case KVM_SET_USER_MEMORY_REGION2: > case KVM_SET_USER_MEMORY_REGION: { > - struct kvm_userspace_memory_region kvm_userspace_mem; > + struct kvm_userspace_memory_region2 mem; > + unsigned long size; > + > + if (ioctl == KVM_SET_USER_MEMORY_REGION) { > + /* > + * Fields beyond struct kvm_userspace_memory_region shouldn't be > + * accessed, but avoid leaking kernel memory in case of a bug. > + */ > + memset(&mem, 0, sizeof(mem)); > + size = sizeof(struct kvm_userspace_memory_region); > + } else { > + size = sizeof(struct kvm_userspace_memory_region2); > + } > + > + /* Ensure the common parts of the two structs are identical. */ > + SANITY_CHECK_MEM_REGION_FIELD(slot); > + SANITY_CHECK_MEM_REGION_FIELD(flags); > + SANITY_CHECK_MEM_REGION_FIELD(guest_phys_addr); > + SANITY_CHECK_MEM_REGION_FIELD(memory_size); > + SANITY_CHECK_MEM_REGION_FIELD(userspace_addr); > > r = -EFAULT; > - if (copy_from_user(&kvm_userspace_mem, argp, > - sizeof(kvm_userspace_mem))) > + if (copy_from_user(&mem, argp, size)) > goto out; > > - r = kvm_vm_ioctl_set_memory_region(kvm, &kvm_userspace_mem); > + r = -EINVAL; > + if (ioctl == KVM_SET_USER_MEMORY_REGION && > + (mem.flags & ~KVM_SET_USER_MEMORY_REGION_V1_FLAGS)) > + goto out; > + > + r = kvm_vm_ioctl_set_memory_region(kvm, &mem); > break; > } > case KVM_GET_DIRTY_LOG: { > -- > 2.39.1 > > >
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index 7025b3751027..bdea1423c5f8 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -1340,6 +1340,7 @@ yet and must be cleared on entry. __u64 guest_phys_addr; __u64 memory_size; /* bytes */ __u64 userspace_addr; /* start of the userspace allocated memory */ + __u64 pad[16]; }; /* for kvm_userspace_memory_region::flags */ @@ -6192,6 +6193,27 @@ to know what fields can be changed for the system register described by ``op0, op1, crn, crm, op2``. KVM rejects ID register values that describe a superset of the features supported by the system. +4.140 KVM_SET_USER_MEMORY_REGION2 +--------------------------------- + +:Capability: KVM_CAP_USER_MEMORY2 +:Architectures: all +:Type: vm ioctl +:Parameters: struct kvm_userspace_memory_region2 (in) +:Returns: 0 on success, -1 on error + +:: + + struct kvm_userspace_memory_region2 { + __u32 slot; + __u32 flags; + __u64 guest_phys_addr; + __u64 memory_size; /* bytes */ + __u64 userspace_addr; /* start of the userspace allocated memory */ + }; + +See KVM_SET_USER_MEMORY_REGION. + 5. The kvm_run structure ======================== diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 2c924075f6f1..7b389f27dffc 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -12576,7 +12576,7 @@ void __user * __x86_set_memory_region(struct kvm *kvm, int id, gpa_t gpa, } for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) { - struct kvm_userspace_memory_region m; + struct kvm_userspace_memory_region2 m; m.slot = id | (i << 16); m.flags = 0; diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 5faba69403ac..4e741ff27af3 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -1146,9 +1146,9 @@ enum kvm_mr_change { }; int kvm_set_memory_region(struct kvm *kvm, - const struct kvm_userspace_memory_region *mem); + const struct kvm_userspace_memory_region2 *mem); int __kvm_set_memory_region(struct kvm *kvm, - const struct kvm_userspace_memory_region *mem); + const struct kvm_userspace_memory_region2 *mem); void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *slot); void kvm_arch_memslots_updated(struct kvm *kvm, u64 gen); int kvm_arch_prepare_memory_region(struct kvm *kvm, diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 211b86de35ac..308cc70bd6ab 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -95,6 +95,16 @@ struct kvm_userspace_memory_region { __u64 userspace_addr; /* start of the userspace allocated memory */ }; +/* for KVM_SET_USER_MEMORY_REGION2 */ +struct kvm_userspace_memory_region2 { + __u32 slot; + __u32 flags; + __u64 guest_phys_addr; + __u64 memory_size; + __u64 userspace_addr; + __u64 pad[16]; +}; + /* * The bit 0 ~ bit 15 of kvm_userspace_memory_region::flags are visible for * userspace, other bits are reserved for kvm internal use which are defined @@ -1201,6 +1211,7 @@ struct kvm_ppc_resize_hpt { #define KVM_CAP_ARM_EAGER_SPLIT_CHUNK_SIZE 228 #define KVM_CAP_ARM_SUPPORTED_BLOCK_SIZES 229 #define KVM_CAP_ARM_SUPPORTED_REG_MASK_RANGES 230 +#define KVM_CAP_USER_MEMORY2 231 #ifdef KVM_CAP_IRQ_ROUTING @@ -1483,6 +1494,8 @@ struct kvm_vfio_spapr_tce { struct kvm_userspace_memory_region) #define KVM_SET_TSS_ADDR _IO(KVMIO, 0x47) #define KVM_SET_IDENTITY_MAP_ADDR _IOW(KVMIO, 0x48, __u64) +#define KVM_SET_USER_MEMORY_REGION2 _IOW(KVMIO, 0x49, \ + struct kvm_userspace_memory_region2) /* enable ucontrol for s390 */ struct kvm_s390_ucas_mapping { diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index dc81279ea385..756b94ecd511 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1580,7 +1580,15 @@ static void kvm_replace_memslot(struct kvm *kvm, } } -static int check_memory_region_flags(const struct kvm_userspace_memory_region *mem) +/* + * Flags that do not access any of the extra space of struct + * kvm_userspace_memory_region2. KVM_SET_USER_MEMORY_REGION_V1_FLAGS + * only allows these. + */ +#define KVM_SET_USER_MEMORY_REGION_V1_FLAGS \ + (KVM_MEM_LOG_DIRTY_PAGES | KVM_MEM_READONLY) + +static int check_memory_region_flags(const struct kvm_userspace_memory_region2 *mem) { u32 valid_flags = KVM_MEM_LOG_DIRTY_PAGES; @@ -1982,7 +1990,7 @@ static bool kvm_check_memslot_overlap(struct kvm_memslots *slots, int id, * Must be called holding kvm->slots_lock for write. */ int __kvm_set_memory_region(struct kvm *kvm, - const struct kvm_userspace_memory_region *mem) + const struct kvm_userspace_memory_region2 *mem) { struct kvm_memory_slot *old, *new; struct kvm_memslots *slots; @@ -2086,7 +2094,7 @@ int __kvm_set_memory_region(struct kvm *kvm, EXPORT_SYMBOL_GPL(__kvm_set_memory_region); int kvm_set_memory_region(struct kvm *kvm, - const struct kvm_userspace_memory_region *mem) + const struct kvm_userspace_memory_region2 *mem) { int r; @@ -2098,7 +2106,7 @@ int kvm_set_memory_region(struct kvm *kvm, EXPORT_SYMBOL_GPL(kvm_set_memory_region); static int kvm_vm_ioctl_set_memory_region(struct kvm *kvm, - struct kvm_userspace_memory_region *mem) + struct kvm_userspace_memory_region2 *mem) { if ((u16)mem->slot >= KVM_USER_MEM_SLOTS) return -EINVAL; @@ -4568,6 +4576,7 @@ static int kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg) { switch (arg) { case KVM_CAP_USER_MEMORY: + case KVM_CAP_USER_MEMORY2: case KVM_CAP_DESTROY_MEMORY_REGION_WORKS: case KVM_CAP_JOIN_MEMORY_REGIONS_WORKS: case KVM_CAP_INTERNAL_ERROR_DATA: @@ -4823,6 +4832,14 @@ static int kvm_vm_ioctl_get_stats_fd(struct kvm *kvm) return fd; } +#define SANITY_CHECK_MEM_REGION_FIELD(field) \ +do { \ + BUILD_BUG_ON(offsetof(struct kvm_userspace_memory_region, field) != \ + offsetof(struct kvm_userspace_memory_region2, field)); \ + BUILD_BUG_ON(sizeof_field(struct kvm_userspace_memory_region, field) != \ + sizeof_field(struct kvm_userspace_memory_region2, field)); \ +} while (0) + static long kvm_vm_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg) { @@ -4845,15 +4862,39 @@ static long kvm_vm_ioctl(struct file *filp, r = kvm_vm_ioctl_enable_cap_generic(kvm, &cap); break; } + case KVM_SET_USER_MEMORY_REGION2: case KVM_SET_USER_MEMORY_REGION: { - struct kvm_userspace_memory_region kvm_userspace_mem; + struct kvm_userspace_memory_region2 mem; + unsigned long size; + + if (ioctl == KVM_SET_USER_MEMORY_REGION) { + /* + * Fields beyond struct kvm_userspace_memory_region shouldn't be + * accessed, but avoid leaking kernel memory in case of a bug. + */ + memset(&mem, 0, sizeof(mem)); + size = sizeof(struct kvm_userspace_memory_region); + } else { + size = sizeof(struct kvm_userspace_memory_region2); + } + + /* Ensure the common parts of the two structs are identical. */ + SANITY_CHECK_MEM_REGION_FIELD(slot); + SANITY_CHECK_MEM_REGION_FIELD(flags); + SANITY_CHECK_MEM_REGION_FIELD(guest_phys_addr); + SANITY_CHECK_MEM_REGION_FIELD(memory_size); + SANITY_CHECK_MEM_REGION_FIELD(userspace_addr); r = -EFAULT; - if (copy_from_user(&kvm_userspace_mem, argp, - sizeof(kvm_userspace_mem))) + if (copy_from_user(&mem, argp, size)) goto out; - r = kvm_vm_ioctl_set_memory_region(kvm, &kvm_userspace_mem); + r = -EINVAL; + if (ioctl == KVM_SET_USER_MEMORY_REGION && + (mem.flags & ~KVM_SET_USER_MEMORY_REGION_V1_FLAGS)) + goto out; + + r = kvm_vm_ioctl_set_memory_region(kvm, &mem); break; } case KVM_GET_DIRTY_LOG: {