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Tue, 13 Jun 2023 07:18:10 -0700 (PDT) X-Google-Smtp-Source: ACHHUZ6Qxd5MF9xG9Y2ZhF+JHE0l7/i45VWWs07LUNcJeZBnEYj9JwVM4ub9aLTrzGq/bx1Sqe3MHg== X-Received: by 2002:a6b:e602:0:b0:777:a8f0:1fc5 with SMTP id g2-20020a6be602000000b00777a8f01fc5mr10407439ioh.5.1686665889883; Tue, 13 Jun 2023 07:18:09 -0700 (PDT) Received: from redhat.com ([38.15.36.239]) by smtp.gmail.com with ESMTPSA id c7-20020a6bfd07000000b00760f256037dsm3841313ioi.44.2023.06.13.07.18.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 13 Jun 2023 07:18:09 -0700 (PDT) Date: Tue, 13 Jun 2023 08:18:08 -0600 From: Alex Williamson To: "Liu, Yi L" Cc: "jgg@nvidia.com" , "Tian, Kevin" , "joro@8bytes.org" , "robin.murphy@arm.com" , "cohuck@redhat.com" , "eric.auger@redhat.com" , "nicolinc@nvidia.com" , "kvm@vger.kernel.org" , "mjrosato@linux.ibm.com" , "chao.p.peng@linux.intel.com" , "yi.y.sun@linux.intel.com" , "peterx@redhat.com" , "jasowang@redhat.com" , "shameerali.kolothum.thodi@huawei.com" , "lulu@redhat.com" , "suravee.suthikulpanit@amd.com" , "intel-gvt-dev@lists.freedesktop.org" , "intel-gfx@lists.freedesktop.org" , "linux-s390@vger.kernel.org" , "Hao, Xudong" , "Zhao, Yan Y" , "Xu, Terrence" , "Jiang, Yanting" , "Duan, Zhenzhong" , "clegoate@redhat.com" Subject: Re: [PATCH v12 18/24] vfio: Add VFIO_DEVICE_BIND_IOMMUFD Message-ID: <20230613081808.049b9e6d.alex.williamson@redhat.com> In-Reply-To: References: <20230602121653.80017-1-yi.l.liu@intel.com> <20230602121653.80017-19-yi.l.liu@intel.com> <20230612162726.16f58ea4.alex.williamson@redhat.com> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.35; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org On Tue, 13 Jun 2023 05:48:46 +0000 "Liu, Yi L" wrote: > > From: Alex Williamson > > Sent: Tuesday, June 13, 2023 6:27 AM > > > > On Fri, 2 Jun 2023 05:16:47 -0700 > > Yi Liu wrote: > > > > > This adds ioctl for userspace to bind device cdev fd to iommufd. > > > > > > VFIO_DEVICE_BIND_IOMMUFD: bind device to an iommufd, hence gain DMA > > > control provided by the iommufd. open_device > > > op is called after bind_iommufd op. > > > > > > Tested-by: Yanting Jiang > > > Tested-by: Shameer Kolothum > > > Tested-by: Terrence Xu > > > Signed-off-by: Yi Liu > > > --- > > > drivers/vfio/device_cdev.c | 123 +++++++++++++++++++++++++++++++++++++ > > > drivers/vfio/vfio.h | 13 ++++ > > > drivers/vfio/vfio_main.c | 5 ++ > > > include/linux/vfio.h | 3 +- > > > include/uapi/linux/vfio.h | 27 ++++++++ > > > 5 files changed, 170 insertions(+), 1 deletion(-) > > > > > > diff --git a/drivers/vfio/device_cdev.c b/drivers/vfio/device_cdev.c > > > index 1c640016a824..a4498ddbe774 100644 > > > --- a/drivers/vfio/device_cdev.c > > > +++ b/drivers/vfio/device_cdev.c > > > @@ -3,6 +3,7 @@ > > > * Copyright (c) 2023 Intel Corporation. > > > */ > > > #include > > > +#include > > > > > > #include "vfio.h" > > > > > > @@ -44,6 +45,128 @@ int vfio_device_fops_cdev_open(struct inode *inode, struct > > file *filep) > > > return ret; > > > } > > > > > > +static void vfio_device_get_kvm_safe(struct vfio_device_file *df) > > > +{ > > > + spin_lock(&df->kvm_ref_lock); > > > + if (df->kvm) > > > + _vfio_device_get_kvm_safe(df->device, df->kvm); > > > + spin_unlock(&df->kvm_ref_lock); > > > +} > > > + > > > +void vfio_df_cdev_close(struct vfio_device_file *df) > > > +{ > > > + struct vfio_device *device = df->device; > > > + > > > + /* > > > + * In the time of close, there is no contention with another one > > > + * changing this flag. So read df->access_granted without lock > > > + * and no smp_load_acquire() is ok. > > > + */ > > > + if (!df->access_granted) > > > + return; > > > + > > > + mutex_lock(&device->dev_set->lock); > > > + vfio_df_close(df); > > > + vfio_device_put_kvm(device); > > > + iommufd_ctx_put(df->iommufd); > > > + device->cdev_opened = false; > > > + mutex_unlock(&device->dev_set->lock); > > > + vfio_device_unblock_group(device); > > > +} > > > + > > > +static struct iommufd_ctx *vfio_get_iommufd_from_fd(int fd) > > > +{ > > > + struct iommufd_ctx *iommufd; > > > + struct fd f; > > > + > > > + f = fdget(fd); > > > + if (!f.file) > > > + return ERR_PTR(-EBADF); > > > + > > > + iommufd = iommufd_ctx_from_file(f.file); > > > + > > > + fdput(f); > > > + return iommufd; > > > +} > > > + > > > +long vfio_df_ioctl_bind_iommufd(struct vfio_device_file *df, > > > + struct vfio_device_bind_iommufd __user *arg) > > > +{ > > > + struct vfio_device *device = df->device; > > > + struct vfio_device_bind_iommufd bind; > > > + unsigned long minsz; > > > + int ret; > > > + > > > + static_assert(__same_type(arg->out_devid, df->devid)); > > > + > > > + minsz = offsetofend(struct vfio_device_bind_iommufd, out_devid); > > > + > > > + if (copy_from_user(&bind, arg, minsz)) > > > + return -EFAULT; > > > + > > > + if (bind.argsz < minsz || bind.flags || bind.iommufd < 0) > > > + return -EINVAL; > > > + > > > + /* BIND_IOMMUFD only allowed for cdev fds */ > > > + if (df->group) > > > + return -EINVAL; > > > + > > > + ret = vfio_device_block_group(device); > > > + if (ret) > > > + return ret; > > > + > > > + mutex_lock(&device->dev_set->lock); > > > + /* one device cannot be bound twice */ > > > + if (df->access_granted) { > > > + ret = -EINVAL; > > > + goto out_unlock; > > > + } > > > + > > > + df->iommufd = vfio_get_iommufd_from_fd(bind.iommufd); > > > + if (IS_ERR(df->iommufd)) { > > > + ret = PTR_ERR(df->iommufd); > > > + df->iommufd = NULL; > > > + goto out_unlock; > > > + } > > > + > > > + /* > > > + * Before the device open, get the KVM pointer currently > > > + * associated with the device file (if there is) and obtain > > > + * a reference. This reference is held until device closed. > > > + * Save the pointer in the device for use by drivers. > > > + */ > > > + vfio_device_get_kvm_safe(df); > > > + > > > + ret = vfio_df_open(df); > > > + if (ret) > > > + goto out_put_kvm; > > > + > > > + ret = copy_to_user(&arg->out_devid, &df->devid, > > > + sizeof(df->devid)) ? -EFAULT : 0; > > > + if (ret) > > > + goto out_close_device; > > > + > > > + /* > > > + * Paired with smp_load_acquire() in vfio_device_fops::ioctl/ > > > + * read/write/mmap > > > + */ > > > + smp_store_release(&df->access_granted, true); > > > + device->cdev_opened = true; > > > + mutex_unlock(&device->dev_set->lock); > > > + return 0; > > > + > > > +out_close_device: > > > + vfio_df_close(df); > > > +out_put_kvm: > > > + vfio_device_put_kvm(device); > > > + iommufd_ctx_put(df->iommufd); > > > + df->iommufd = NULL; > > > +out_unlock: > > > + mutex_unlock(&device->dev_set->lock); > > > + vfio_device_unblock_group(device); > > > + return ret; > > > +} > > > + > > > static char *vfio_device_devnode(const struct device *dev, umode_t *mode) > > > { > > > return kasprintf(GFP_KERNEL, "vfio/devices/%s", dev_name(dev)); > > > diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h > > > index d12b5b524bfc..42de40d2cd4d 100644 > > > --- a/drivers/vfio/vfio.h > > > +++ b/drivers/vfio/vfio.h > > > @@ -287,6 +287,9 @@ static inline void vfio_device_del(struct vfio_device *device) > > > } > > > > > > int vfio_device_fops_cdev_open(struct inode *inode, struct file *filep); > > > +void vfio_df_cdev_close(struct vfio_device_file *df); > > > +long vfio_df_ioctl_bind_iommufd(struct vfio_device_file *df, > > > + struct vfio_device_bind_iommufd __user *arg); > > > int vfio_cdev_init(struct class *device_class); > > > void vfio_cdev_cleanup(void); > > > #else > > > @@ -310,6 +313,16 @@ static inline int vfio_device_fops_cdev_open(struct inode > > *inode, > > > return 0; > > > } > > > > > > +static inline void vfio_df_cdev_close(struct vfio_device_file *df) > > > +{ > > > +} > > > + > > > +static inline long vfio_df_ioctl_bind_iommufd(struct vfio_device_file *df, > > > + struct vfio_device_bind_iommufd __user > > *arg) > > > +{ > > > + return -EOPNOTSUPP; > > > +} > > > + > > > static inline int vfio_cdev_init(struct class *device_class) > > > { > > > return 0; > > > diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c > > > index ef55af75f459..9ba4d420eda2 100644 > > > --- a/drivers/vfio/vfio_main.c > > > +++ b/drivers/vfio/vfio_main.c > > > @@ -572,6 +572,8 @@ static int vfio_device_fops_release(struct inode *inode, struct > > file *filep) > > > > > > if (df->group) > > > vfio_df_group_close(df); > > > + else > > > + vfio_df_cdev_close(df); > > > > > > vfio_device_put_registration(device); > > > > > > @@ -1145,6 +1147,9 @@ static long vfio_device_fops_unl_ioctl(struct file *filep, > > > struct vfio_device *device = df->device; > > > int ret; > > > > > > + if (cmd == VFIO_DEVICE_BIND_IOMMUFD) > > > + return vfio_df_ioctl_bind_iommufd(df, (void __user *)arg); > > > + > > > /* Paired with smp_store_release() following vfio_df_open() */ > > > if (!smp_load_acquire(&df->access_granted)) > > > return -EINVAL; > > > diff --git a/include/linux/vfio.h b/include/linux/vfio.h > > > index 83cc5dc28b7a..e80a8ac86e46 100644 > > > --- a/include/linux/vfio.h > > > +++ b/include/linux/vfio.h > > > @@ -66,6 +66,7 @@ struct vfio_device { > > > struct iommufd_device *iommufd_device; > > > bool iommufd_attached; > > > #endif > > > + bool cdev_opened:1; > > > > Perhaps a more strongly defined data type here as well and roll > > iommufd_attached into the same bit field scheme. > > Ok, then needs to make iommufd_attached always defined. That does not follow. Thanks, Alex