Messages in this thread | | | Date | Thu, 10 Feb 2022 10:43:26 +0100 | Subject | Re: [PATCH v3 05/10] KVM: s390: Add optional storage key checking to MEMOP IOCTL | From | Christian Borntraeger <> |
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Am 10.02.22 um 10:40 schrieb Janis Schoetterl-Glausch: > On 2/10/22 10:29, Christian Borntraeger wrote: >> Am 09.02.22 um 18:04 schrieb Janis Schoetterl-Glausch: >>> User space needs a mechanism to perform key checked accesses when >>> emulating instructions. >>> >>> The key can be passed as an additional argument. >>> Having an additional argument is flexible, as user space can >>> pass the guest PSW's key, in order to make an access the same way the >>> CPU would, or pass another key if necessary. >>> >>> Signed-off-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com> >>> Acked-by: Janosch Frank <frankja@linux.ibm.com> >>> Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com> >> >> Claudio, Janosch, can you confirm that this is still valid? >> >> >> Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com> > > Not @linux.ibm.com?
Yes, of course. Old habits... Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
>> >> minor thing below >>> --- >>> arch/s390/kvm/kvm-s390.c | 30 ++++++++++++++++++++---------- >>> include/uapi/linux/kvm.h | 6 +++++- >>> 2 files changed, 25 insertions(+), 11 deletions(-) >>> >>> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c >>> index cf347e1a4f17..85763ec7bc60 100644 >>> --- a/arch/s390/kvm/kvm-s390.c >>> +++ b/arch/s390/kvm/kvm-s390.c >>> @@ -32,6 +32,7 @@ >>> #include <linux/sched/signal.h> >>> #include <linux/string.h> >>> #include <linux/pgtable.h> >>> +#include <linux/bitfield.h> >> >> do we still need that after the changes? > > No, not since we moved the key out of the flags. >> >>> #include <asm/asm-offsets.h> >>> #include <asm/lowcore.h> >>> @@ -2359,6 +2360,11 @@ static int kvm_s390_handle_pv(struct kvm *kvm, struct kvm_pv_cmd *cmd) >>> return r; >>> } >>> +static bool access_key_invalid(u8 access_key) >>> +{ >>> + return access_key > 0xf; >>> +} >>> + >>> long kvm_arch_vm_ioctl(struct file *filp, >>> unsigned int ioctl, unsigned long arg) >>> { >>> @@ -4690,17 +4696,19 @@ static long kvm_s390_guest_mem_op(struct kvm_vcpu *vcpu, >>> void *tmpbuf = NULL; >>> int r = 0; >>> const u64 supported_flags = KVM_S390_MEMOP_F_INJECT_EXCEPTION >>> - | KVM_S390_MEMOP_F_CHECK_ONLY; >>> + | KVM_S390_MEMOP_F_CHECK_ONLY >>> + | KVM_S390_MEMOP_F_SKEY_PROTECTION; >>> if (mop->flags & ~supported_flags || mop->ar >= NUM_ACRS || !mop->size) >>> return -EINVAL; >>> - >>> if (mop->size > MEM_OP_MAX_SIZE) >>> return -E2BIG; >>> - >>> if (kvm_s390_pv_cpu_is_protected(vcpu)) >>> return -EINVAL; >>> - >>> + if (mop->flags & KVM_S390_MEMOP_F_SKEY_PROTECTION) { >>> + if (access_key_invalid(mop->key)) >>> + return -EINVAL; >>> + } >>> if (!(mop->flags & KVM_S390_MEMOP_F_CHECK_ONLY)) { >>> tmpbuf = vmalloc(mop->size); >>> if (!tmpbuf) >>> @@ -4710,11 +4718,12 @@ static long kvm_s390_guest_mem_op(struct kvm_vcpu *vcpu, >>> switch (mop->op) { >>> case KVM_S390_MEMOP_LOGICAL_READ: >>> if (mop->flags & KVM_S390_MEMOP_F_CHECK_ONLY) { >>> - r = check_gva_range(vcpu, mop->gaddr, mop->ar, >>> - mop->size, GACC_FETCH, 0); >>> + r = check_gva_range(vcpu, mop->gaddr, mop->ar, mop->size, >>> + GACC_FETCH, mop->key); >>> break; >>> } >>> - r = read_guest(vcpu, mop->gaddr, mop->ar, tmpbuf, mop->size); >>> + r = read_guest_with_key(vcpu, mop->gaddr, mop->ar, tmpbuf, >>> + mop->size, mop->key); >>> if (r == 0) { >>> if (copy_to_user(uaddr, tmpbuf, mop->size)) >>> r = -EFAULT; >>> @@ -4722,15 +4731,16 @@ static long kvm_s390_guest_mem_op(struct kvm_vcpu *vcpu, >>> break; >>> case KVM_S390_MEMOP_LOGICAL_WRITE: >>> if (mop->flags & KVM_S390_MEMOP_F_CHECK_ONLY) { >>> - r = check_gva_range(vcpu, mop->gaddr, mop->ar, >>> - mop->size, GACC_STORE, 0); >>> + r = check_gva_range(vcpu, mop->gaddr, mop->ar, mop->size, >>> + GACC_STORE, mop->key); >>> break; >>> } >>> if (copy_from_user(tmpbuf, uaddr, mop->size)) { >>> r = -EFAULT; >>> break; >>> } >>> - r = write_guest(vcpu, mop->gaddr, mop->ar, tmpbuf, mop->size); >>> + r = write_guest_with_key(vcpu, mop->gaddr, mop->ar, tmpbuf, >>> + mop->size, mop->key); >>> break; >>> } >>> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h >>> index b46bcdb0cab1..44558cf4c52e 100644 >>> --- a/include/uapi/linux/kvm.h >>> +++ b/include/uapi/linux/kvm.h >>> @@ -562,7 +562,10 @@ struct kvm_s390_mem_op { >>> __u32 op; /* type of operation */ >>> __u64 buf; /* buffer in userspace */ >>> union { >>> - __u8 ar; /* the access register number */ >>> + struct { >>> + __u8 ar; /* the access register number */ >>> + __u8 key; /* access key, ignored if flag unset */ >>> + }; >>> __u32 sida_offset; /* offset into the sida */ >>> __u8 reserved[32]; /* should be set to 0 */ >>> }; >>> @@ -575,6 +578,7 @@ struct kvm_s390_mem_op { >>> /* flags for kvm_s390_mem_op->flags */ >>> #define KVM_S390_MEMOP_F_CHECK_ONLY (1ULL << 0) >>> #define KVM_S390_MEMOP_F_INJECT_EXCEPTION (1ULL << 1) >>> +#define KVM_S390_MEMOP_F_SKEY_PROTECTION (1ULL << 2) >>> /* for KVM_INTERRUPT */ >>> struct kvm_interrupt { >
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