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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Tue, 28 May 2019 11:32:33 +0100 Received: from d06av24.portsmouth.uk.ibm.com (mk.ibm.com [9.149.105.60]) by b06cxnps4074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x4SAWWRD49873028 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 28 May 2019 10:32:32 GMT Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 1383742045; Tue, 28 May 2019 10:32:32 +0000 (GMT) Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D2FC94203F; Tue, 28 May 2019 10:32:31 +0000 (GMT) Received: from oc7455500831.ibm.com (unknown [9.152.224.177]) by d06av24.portsmouth.uk.ibm.com (Postfix) with ESMTP; Tue, 28 May 2019 10:32:31 +0000 (GMT) Subject: Re: [PATCH] kvm: add kvm cap values to debugfs To: Suraj Jitindar Singh , kvm@vger.kernel.org Cc: pbonzini@redhat.com, rkrcmar@redhat.com, paulus@ozlabs.org, dja@axtens.net References: <20190528083535.27643-1-sjitindarsingh@gmail.com> From: Christian Borntraeger Openpgp: preference=signencrypt Autocrypt: addr=borntraeger@de.ibm.com; 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Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190528083535.27643-1-sjitindarsingh@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 x-cbid: 19052810-0020-0000-0000-00000341312F X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19052810-0021-0000-0000-000021942C45 Message-Id: <7622b8ab-c2a4-8920-afe3-d2a9089cbd10@de.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-05-28_04:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1905280070 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 28.05.19 10:35, Suraj Jitindar Singh wrote: > KVM capabilities are used to communicate the availability of certain > capabilities to userspace. > > It might be nice to know these values without having to add debug > printing to the userspace tool consuming this data. > > Thus add a file in the kvm per vm debugfs file named "caps" which > contains a file for each capability number which when read returns what > would be returned when querying that capability. > > Signed-off-by: Suraj Jitindar Singh > > --- > > I'm not sure if it'd be better to keep a per arch list of the revelevant > capabilities to avoid adding an entry for irrelevant ones. Comments? > --- > include/linux/kvm_host.h | 1 + > include/uapi/linux/kvm.h | 1 + > virt/kvm/kvm_main.c | 31 +++++++++++++++++++++++++++++++ > 3 files changed, 33 insertions(+) > > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > index 79fa4426509c..6cb45a8de818 100644 > --- a/include/linux/kvm_host.h > +++ b/include/linux/kvm_host.h > @@ -500,6 +500,7 @@ struct kvm { > bool manual_dirty_log_protect; > struct dentry *debugfs_dentry; > struct kvm_stat_data **debugfs_stat_data; > + int debugfs_cap_data[KVM_CAP_MAX + 1]; > struct srcu_struct srcu; > struct srcu_struct irq_srcu; > pid_t userspace_pid; > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h > index 2fe12b40d503..7b5042ec5902 100644 > --- a/include/uapi/linux/kvm.h > +++ b/include/uapi/linux/kvm.h > @@ -993,6 +993,7 @@ struct kvm_ppc_resize_hpt { > #define KVM_CAP_ARM_SVE 170 > #define KVM_CAP_ARM_PTRAUTH_ADDRESS 171 > #define KVM_CAP_ARM_PTRAUTH_GENERIC 172 > +#define KVM_CAP_MAX KVM_CAP_ARM_PTRAUTH_GENERIC > > #ifdef KVM_CAP_IRQ_ROUTING > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 134ec0283a8a..b85a43263fb7 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -117,6 +117,7 @@ EXPORT_SYMBOL_GPL(kvm_debugfs_dir); > static int kvm_debugfs_num_entries; > static const struct file_operations *stat_fops_per_vm[]; > > +static long kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg); > static long kvm_vcpu_ioctl(struct file *file, unsigned int ioctl, > unsigned long arg); > #ifdef CONFIG_KVM_COMPAT > @@ -594,6 +595,33 @@ static void kvm_destroy_vm_debugfs(struct kvm *kvm) > } > } > > +static int vm_cap_get(void *data, u64 *val) > +{ > + *val = *((int *) data); > + > + return 0; > +} > + > +DEFINE_SIMPLE_ATTRIBUTE(cap_fops, vm_cap_get, NULL, "%llu\n"); > + > +static void kvm_create_vm_cap_debugfs(struct kvm *kvm) > +{ > + char *dir_name = "caps"; > + struct dentry *dentry_p; > + int i; > + > + dentry_p = debugfs_create_dir(dir_name, kvm->debugfs_dentry); > + > + for (i = 0; i <= KVM_CAP_MAX; i++) { > + int *cap = &kvm->debugfs_cap_data[i]; > + char file_name[ITOA_MAX_LEN]; > + > + *cap = kvm_vm_ioctl_check_extension_generic(kvm, i); > + snprintf(file_name, sizeof(file_name), "%d", i); > + debugfs_create_file(file_name, 0444, dentry_p, cap, &cap_fops); > + } So you get the information of the capabilities during creation of the VM. Are there any capabilities that might change over time? I do not know right now, but wouldnt it be better to actually call kvm_vm_ioctl_check_extension_generic in the fops callback? > +} > + > static int kvm_create_vm_debugfs(struct kvm *kvm, int fd) > { > char dir_name[ITOA_MAX_LEN * 2]; > @@ -623,6 +651,9 @@ static int kvm_create_vm_debugfs(struct kvm *kvm, int fd) > debugfs_create_file(p->name, 0644, kvm->debugfs_dentry, > stat_data, stat_fops_per_vm[p->kind]); > } > + > + kvm_create_vm_cap_debugfs(kvm); > + > return 0; > } >