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Tue, 18 Jan 2022 11:51:26 +0000 (GMT) Received: from [9.171.19.84] (unknown [9.171.19.84]) by d06av26.portsmouth.uk.ibm.com (Postfix) with ESMTP; Tue, 18 Jan 2022 11:51:26 +0000 (GMT) Message-ID: <2bd8dd31-0c08-a03b-33b3-67d7adc78726@linux.ibm.com> Date: Tue, 18 Jan 2022 12:51:26 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.4.0 Subject: Re: [RFC PATCH v1 05/10] KVM: s390: Add optional storage key checking to MEMOP IOCTL Content-Language: en-US To: Janis Schoetterl-Glausch , Janosch Frank , Heiko Carstens , Vasily Gorbik Cc: Claudio Imbrenda , David Hildenbrand , Alexander Gordeev , kvm@vger.kernel.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org References: <20220118095210.1651483-1-scgl@linux.ibm.com> <20220118095210.1651483-6-scgl@linux.ibm.com> From: Christian Borntraeger In-Reply-To: <20220118095210.1651483-6-scgl@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: 2m9v-qkGO2dcM6m5Gq5rJf8PC8IKuIKa X-Proofpoint-GUID: nT_KZZE9z1DpFYdkyx0gDhu0rarlProb X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.816,Hydra:6.0.425,FMLib:17.11.62.513 definitions=2022-01-18_03,2022-01-18_01,2021-12-02_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 clxscore=1015 priorityscore=1501 lowpriorityscore=0 malwarescore=0 impostorscore=0 mlxlogscore=999 suspectscore=0 bulkscore=0 adultscore=0 mlxscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2110150000 definitions=main-2201180070 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Am 18.01.22 um 10:52 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 via the flags field. > As reserved flags need to be 0, and key 0 matches all storage keys, > by default no key checking is performed, as before. > 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 > Acked-by: Janosch Frank > Reviewed-by: Claudio Imbrenda > --- > arch/s390/kvm/kvm-s390.c | 21 ++++++++++++++------- > include/uapi/linux/kvm.h | 1 + > 2 files changed, 15 insertions(+), 7 deletions(-) > > diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c > index 38b304e81c57..c4acdb025ff1 100644 > --- a/arch/s390/kvm/kvm-s390.c > +++ b/arch/s390/kvm/kvm-s390.c > @@ -32,6 +32,7 @@ > #include > #include > #include > +#include > > #include > #include > @@ -4727,9 +4728,11 @@ static long kvm_s390_guest_mem_op(struct kvm_vcpu *vcpu, > { > void __user *uaddr = (void __user *)mop->buf; > void *tmpbuf = NULL; > + char access_key = 0; > 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_SKEYS_ACC; I think it would be better to just have a flag here (single bit) to check the key and then embed the key value in the payload. union { __u8 ar; /* the access register number */ __u32 sida_offset; /* offset into the sida */ __u8 reserved[32]; /* should be set to 0 */ }; There are cases when we need both, AR and key so maybe an unname struct is the easiest. diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 1daa45268de2..e8fa1f82d472 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; /* effective storage key */ + }; __u32 sida_offset; /* offset into the sida */ __u8 reserved[32]; /* should be set to 0 */ }; (or acc instead of key) > > if (mop->flags & ~supported_flags || mop->ar >= NUM_ACRS || !mop->size) > return -EINVAL; > @@ -4746,14 +4749,17 @@ static long kvm_s390_guest_mem_op(struct kvm_vcpu *vcpu, > return -ENOMEM; > } > > + access_key = FIELD_GET(KVM_S390_MEMOP_F_SKEYS_ACC, mop->flags); > + > 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, access_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, access_key); > if (r == 0) { > if (copy_to_user(uaddr, tmpbuf, mop->size)) > r = -EFAULT; > @@ -4761,15 +4767,16 @@ 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, access_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, access_key); > break; > } > > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h > index 1daa45268de2..e3f450b2f346 100644 > --- a/include/uapi/linux/kvm.h > +++ b/include/uapi/linux/kvm.h > @@ -575,6 +575,7 @@ 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_SKEYS_ACC 0x0f00ULL > > /* for KVM_INTERRUPT */ > struct kvm_interrupt {