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[199.106.103.254]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-33e96848e18sm1178819eec.17.2026.09.22.15.53.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 22 Sep 2026 15:53:42 -0700 (PDT) Date: Tue, 22 Sep 2026 15:53:38 -0700 From: Jonathan Cameron To: Suzuki K Poulose Cc: kvm@vger.kernel.org, kvmarm@lists.linux.dev, maz@kernel.org, will@kernel.org, catalin.marinas@arm.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, steven.price@arm.com, aneesh.kumar@kernel.org, oupton@kernel.org, gshan@redhat.com, joey.gouly@arm.com, tabba@google.com, yuzenghui@huawei.com, linux-coco@lists.linux.dev, gankulkarni@os.amperecomputing.com, sdonthineni@nvidia.com, alpergun@google.com, fj0570is@fujitsu.com, WeiLin.Chang@arm.com, lpieralisi@kernel.org, enju.kohei@fujitsu.com Subject: Re: [PATCH v19 16/20] KVM: arm64: CCA: Don't expose unsupported capabilities for realm guests Message-ID: <20260922155338.000064e5@oss.qualcomm.com> In-Reply-To: <20260920212845.707-17-suzuki.poulose@arm.com> References: <20260920212845.707-1-suzuki.poulose@arm.com> <20260920212845.707-17-suzuki.poulose@arm.com> Organization: Qualcomm X-Mailer: Claws Mail 4.4.0 (GTK 3.24.51; x86_64-w64-mingw32) Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTIyMDMwMyBTYWx0ZWRfX78gEkrNDAzzj eHIEwJluTLgjRKecs4ysbGw2evtv/z3VRvQrraM7kF3wYMX6RmOXnOL+92BtgR/YAnDMnDKwg2Q XprAnNsn3WTa8Z/SFB5z3sMFJOOkjkabAZEbRkNJZzvrIDiMKJjH4/NXURP/t7RXR6v3L16AnT9 6M94UnVrdbA+FdwmfnFBOFP6IUqb0GhR8LqN5HiFklAFC0NXRn2bGID20HK77dmAyg8w7s6D7qR p8NRkTwWPCXEOoYEiU2dgJok/zyB1C5iAM8V99S3JMFRnbyjDdHIrbmVBfcpjltmNGrTsSgx4Jz Qb5ySfWTi5jrXFGIVF8CmZLslv2HR5byCTG6w4WzMdma88THLd56mBz68X8jF8PhbdLlyR+ozgW imyO6MLl/KGtBwlUve4xTPqvCY+KH85UK/McAn4ddqmxjUnremlqG0e9qLq6yU23U8HCt4TvPS/ ueyoYehBUQvcA4AKpNg== X-Authority-Analysis: v=2.4 cv=VKdIDNPX c=1 sm=1 tr=0 ts=6ab306f7 cx=c_pps a=PfFC4Oe2JQzmKTvty2cRDw==:117 a=JYp8KDb2vCoCEuGobkYCKw==:17 a=kj9zAlcOel0A:10 a=VdqzKS8jKosA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=YMgV9FUhrdKAYTUUvYB2:22 a=7CQSdrXTAAAA:8 a=z_NLTHdx8yjNkCs6FmoA:9 a=CjuIK1q_8ugA:10 a=6Ab_bkdmUrQuMsNx7PHu:22 a=a-qgeE7W1pNrGK8U0ZQC:22 X-Proofpoint-GUID: rbFz94GeQdpzPd-QGNAxVB2yileb6Ahw X-Proofpoint-Spam-Info: AW1haW4tMjYwOTIyMDMwMyBTYWx0ZWRfXwD82MhWRGkk/ qg9jBxn6mVlM/+5ZwT1bcGC766apU0qAVDQSkh+NqFXfvObMpjpnO5RBgKabVSDe7H/ab2+ATHV tGYZr5OQM8NrSm+aWYEgzM+4P43kqiM= X-Proofpoint-ORIG-GUID: rbFz94GeQdpzPd-QGNAxVB2yileb6Ahw X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-09-22_03,2026-09-21_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 impostorscore=0 phishscore=0 spamscore=0 malwarescore=0 suspectscore=0 bulkscore=0 clxscore=1015 adultscore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2609220303 On Sun, 20 Sep 2026 22:28:41 +0100 Suzuki K Poulose wrote: > Limit the capabilities that are allowed for Realm VMs. Similarly block > the vm_ioctls backed by the capabilities. > > Repurpose the kvm_pkvm_ioctl_allowed() to support both pKVM and Realm > ioctls. Rename the helper to kvm_vm_ioctl_allowed() and move it > into arch/arm64/kvm/arm.c. Also add a generic kvm_vm_ext_allowed() > to handle pKVM and Realm capability filtering and route them accordingly. > > Signed-off-by: Suzuki K Poulose One trivial - otherwise seems fine to me. > diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c > index 86e705330d7bd..eab8543a4194d 100644 > --- a/arch/arm64/kvm/arm.c > +++ b/arch/arm64/kvm/arm.c > +/* > + * Check whether the KVM VM IOCTL is allowed. For pKVM and Realm VMs, certain > + * ioctls are not allowed. Further, certain features are allowed only for > + * non-protected VMs in pKVM. > + */ > +static inline bool kvm_vm_ioctl_allowed(struct kvm *kvm, unsigned int ioctl) > +{ > + long ext; > + int r; > + > + /* > + * We are guaranteed to be called with a valid kvm instance, as the > + * only caller is kvm_arch_vm_ioctl(). Catch any deviations, as we > + * rely on the kvm instance below. > + */ > + if (WARN_ON_ONCE(!kvm)) > + return false; > + > + /* Cover both pKVM host and Realm VMs */ Comment is a little confusing. This is the path that covers everything other than those two. Maybe 'Rest of function covers both...' > + if (!kvm_vm_hyp_is_distrusting(kvm)) > + return true; > + > + r = kvm_get_cap_for_kvm_ioctl(ioctl, &ext); > + if (WARN_ON_ONCE(r < 0)) > + return false; > + > + return kvm_vm_ext_allowed(kvm, ext); > +}