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Tue, 17 May 2022 12:25:43 +0000 (GMT) Message-ID: <55c5780a-de9c-a4d3-8c77-691242085076@linux.ibm.com> Date: Tue, 17 May 2022 14:25:43 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 Subject: Re: [PATCH v3 1/2] KVM: s390: Don't indicate suppression on dirtying, failing memop Content-Language: en-US To: Janis Schoetterl-Glausch , Paolo Bonzini , Jonathan Corbet , Janosch Frank , Claudio Imbrenda , Heiko Carstens , Vasily Gorbik , Alexander Gordeev Cc: David Hildenbrand , Sven Schnelle , kvm@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org References: <20220512131019.2594948-1-scgl@linux.ibm.com> <20220512131019.2594948-2-scgl@linux.ibm.com> From: Christian Borntraeger In-Reply-To: <20220512131019.2594948-2-scgl@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: c0mFL0rtz00ZoG-niShLrUldbLBgntha X-Proofpoint-ORIG-GUID: gYW-wVEJRJZf68u3J8LhJMBkQh3u4aeI X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.858,Hydra:6.0.486,FMLib:17.11.64.514 definitions=2022-05-17_02,2022-05-17_02,2022-02-23_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 bulkscore=0 spamscore=0 impostorscore=0 adultscore=0 lowpriorityscore=0 suspectscore=0 mlxscore=0 malwarescore=0 mlxlogscore=999 clxscore=1015 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2202240000 definitions=main-2205170073 Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org Am 12.05.22 um 15:10 schrieb Janis Schoetterl-Glausch: > If user space uses a memop to emulate an instruction and that > memop fails, the execution of the instruction ends. > Instruction execution can end in different ways, one of which is > suppression, which requires that the instruction execute like a no-op. > A writing memop that spans multiple pages and fails due to key > protection may have modified guest memory, as a result, the likely > correct ending is termination. Therefore, do not indicate a > suppressing instruction ending in this case. > > Signed-off-by: Janis Schoetterl-Glausch Reviewed-by: Christian Borntraeger > --- > Documentation/virt/kvm/api.rst | 6 ++++++ > arch/s390/kvm/gaccess.c | 22 ++++++++++++++++++---- > 2 files changed, 24 insertions(+), 4 deletions(-) > > diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst > index 4a900cdbc62e..b6aba4f50db7 100644 > --- a/Documentation/virt/kvm/api.rst > +++ b/Documentation/virt/kvm/api.rst > @@ -3754,12 +3754,18 @@ in case of KVM_S390_MEMOP_F_CHECK_ONLY), the ioctl returns a positive > error number indicating the type of exception. This exception is also > raised directly at the corresponding VCPU if the flag > KVM_S390_MEMOP_F_INJECT_EXCEPTION is set. > +On protection exceptions, unless specified otherwise, the injected > +translation-exception identifier (TEID) indicates suppression. > > If the KVM_S390_MEMOP_F_SKEY_PROTECTION flag is set, storage key > protection is also in effect and may cause exceptions if accesses are > prohibited given the access key designated by "key"; the valid range is 0..15. > KVM_S390_MEMOP_F_SKEY_PROTECTION is available if KVM_CAP_S390_MEM_OP_EXTENSION > is > 0. > +Since the accessed memory may span multiple pages and those pages might have > +different storage keys, it is possible that a protection exception occurs > +after memory has been modified. In this case, if the exception is injected, > +the TEID does not indicate suppression. > > Absolute read/write: > ^^^^^^^^^^^^^^^^^^^^ > diff --git a/arch/s390/kvm/gaccess.c b/arch/s390/kvm/gaccess.c > index d53a183c2005..227ed0009354 100644 > --- a/arch/s390/kvm/gaccess.c > +++ b/arch/s390/kvm/gaccess.c > @@ -491,8 +491,8 @@ enum prot_type { > PROT_TYPE_IEP = 4, > }; > > -static int trans_exc(struct kvm_vcpu *vcpu, int code, unsigned long gva, > - u8 ar, enum gacc_mode mode, enum prot_type prot) > +static int trans_exc_ending(struct kvm_vcpu *vcpu, int code, unsigned long gva, u8 ar, > + enum gacc_mode mode, enum prot_type prot, bool terminate) > { > struct kvm_s390_pgm_info *pgm = &vcpu->arch.pgm; > struct trans_exc_code_bits *tec; > @@ -520,6 +520,11 @@ static int trans_exc(struct kvm_vcpu *vcpu, int code, unsigned long gva, > tec->b61 = 1; > break; > } > + if (terminate) { > + tec->b56 = 0; > + tec->b60 = 0; > + tec->b61 = 0; > + } > fallthrough; > case PGM_ASCE_TYPE: > case PGM_PAGE_TRANSLATION: > @@ -552,6 +557,12 @@ static int trans_exc(struct kvm_vcpu *vcpu, int code, unsigned long gva, > return code; > } > > +static int trans_exc(struct kvm_vcpu *vcpu, int code, unsigned long gva, u8 ar, > + enum gacc_mode mode, enum prot_type prot) > +{ > + return trans_exc_ending(vcpu, code, gva, ar, mode, prot, false); > +} > + > static int get_vcpu_asce(struct kvm_vcpu *vcpu, union asce *asce, > unsigned long ga, u8 ar, enum gacc_mode mode) > { > @@ -1109,8 +1120,11 @@ int access_guest_with_key(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar, > data += fragment_len; > ga = kvm_s390_logical_to_effective(vcpu, ga + fragment_len); > } > - if (rc > 0) > - rc = trans_exc(vcpu, rc, ga, ar, mode, prot); > + if (rc > 0) { > + bool terminate = (mode == GACC_STORE) && (idx > 0); > + > + rc = trans_exc_ending(vcpu, rc, ga, ar, mode, prot, terminate); > + } > out_unlock: > if (need_ipte_lock) > ipte_unlock(vcpu);