From: Eric Auger <eric.auger@redhat.com>
To: Yi Liu <yi.l.liu@intel.com>,
alex.williamson@redhat.com, jgg@nvidia.com, kevin.tian@intel.com
Cc: linux-s390@vger.kernel.org, yi.y.sun@linux.intel.com,
kvm@vger.kernel.org, mjrosato@linux.ibm.com,
intel-gvt-dev@lists.freedesktop.org, joro@8bytes.org,
cohuck@redhat.com, xudong.hao@intel.com, peterx@redhat.com,
yan.y.zhao@intel.com, terrence.xu@intel.com, nicolinc@nvidia.com,
shameerali.kolothum.thodi@huawei.com,
suravee.suthikulpanit@amd.com, intel-gfx@lists.freedesktop.org,
chao.p.peng@linux.intel.com, lulu@redhat.com,
robin.murphy@arm.com, jasowang@redhat.com,
yanting.jiang@intel.com
Subject: Re: [Intel-gfx] [PATCH v9 08/25] vfio: Block device access via device fd until device is opened
Date: Thu, 6 Apr 2023 16:08:19 +0200 [thread overview]
Message-ID: <d8ebec5f-1742-2e51-8c6c-f02d46a6685f@redhat.com> (raw)
In-Reply-To: <20230401151833.124749-9-yi.l.liu@intel.com>
On 4/1/23 17:18, Yi Liu wrote:
> Allow the vfio_device file to be in a state where the device FD is
> opened but the device cannot be used by userspace (i.e. its .open_device()
> hasn't been called). This inbetween state is not used when the device
> FD is spawned from the group FD, however when we create the device FD
> directly by opening a cdev it will be opened in the blocked state.
>
> The reason for the inbetween state is that userspace only gets a FD but
> doesn't gain access permission until binding the FD to an iommufd. So in
> the blocked state, only the bind operation is allowed. Completing bind
> will allow user to further access the device.
>
> This is implemented by adding a flag in struct vfio_device_file to mark
> the blocked state and using a simple smp_load_acquire() to obtain the
> flag value and serialize all the device setup with the thread accessing
> this device.
>
> Following this lockless scheme, it can safely handle the device FD
> unbound->bound but it cannot handle bound->unbound. To allow this we'd
> need to add a lock on all the vfio ioctls which seems costly. So once
> device FD is bound, it remains bound until the FD is closed.
>
> Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
> Reviewed-by: Kevin Tian <kevin.tian@intel.com>
> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
> Tested-by: Terrence Xu <terrence.xu@intel.com>
> Tested-by: Nicolin Chen <nicolinc@nvidia.com>
> Tested-by: Matthew Rosato <mjrosato@linux.ibm.com>
> Tested-by: Yanting Jiang <yanting.jiang@intel.com>
> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Eric
> ---
> drivers/vfio/group.c | 11 ++++++++++-
> drivers/vfio/vfio.h | 1 +
> drivers/vfio/vfio_main.c | 42 ++++++++++++++++++++++++++++++++++------
> 3 files changed, 47 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/vfio/group.c b/drivers/vfio/group.c
> index 9a7b2765eef6..71f0a9a4016e 100644
> --- a/drivers/vfio/group.c
> +++ b/drivers/vfio/group.c
> @@ -194,9 +194,18 @@ static int vfio_device_group_open(struct vfio_device_file *df)
> df->iommufd = device->group->iommufd;
>
> ret = vfio_device_open(df);
> - if (ret)
> + if (ret) {
> df->iommufd = NULL;
> + goto out_put_kvm;
> + }
> +
> + /*
> + * Paired with smp_load_acquire() in vfio_device_fops::ioctl/
> + * read/write/mmap and vfio_file_has_device_access()
> + */
> + smp_store_release(&df->access_granted, true);
>
> +out_put_kvm:
> if (device->open_count == 0)
> vfio_device_put_kvm(device);
>
> diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
> index cffc08f5a6f1..854f2c97cb9a 100644
> --- a/drivers/vfio/vfio.h
> +++ b/drivers/vfio/vfio.h
> @@ -18,6 +18,7 @@ struct vfio_container;
>
> struct vfio_device_file {
> struct vfio_device *device;
> + bool access_granted;
> spinlock_t kvm_ref_lock; /* protect kvm field */
> struct kvm *kvm;
> struct iommufd_ctx *iommufd; /* protected by struct vfio_device_set::lock */
> diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
> index 2ea6cb6d03c7..6d5d3c2180c8 100644
> --- a/drivers/vfio/vfio_main.c
> +++ b/drivers/vfio/vfio_main.c
> @@ -1114,6 +1114,10 @@ static long vfio_device_fops_unl_ioctl(struct file *filep,
> struct vfio_device *device = df->device;
> int ret;
>
> + /* Paired with smp_store_release() following vfio_device_open() */
> + if (!smp_load_acquire(&df->access_granted))
> + return -EINVAL;
> +
> ret = vfio_device_pm_runtime_get(device);
> if (ret)
> return ret;
> @@ -1141,6 +1145,10 @@ static ssize_t vfio_device_fops_read(struct file *filep, char __user *buf,
> struct vfio_device_file *df = filep->private_data;
> struct vfio_device *device = df->device;
>
> + /* Paired with smp_store_release() following vfio_device_open() */
> + if (!smp_load_acquire(&df->access_granted))
> + return -EINVAL;
> +
> if (unlikely(!device->ops->read))
> return -EINVAL;
>
> @@ -1154,6 +1162,10 @@ static ssize_t vfio_device_fops_write(struct file *filep,
> struct vfio_device_file *df = filep->private_data;
> struct vfio_device *device = df->device;
>
> + /* Paired with smp_store_release() following vfio_device_open() */
> + if (!smp_load_acquire(&df->access_granted))
> + return -EINVAL;
> +
> if (unlikely(!device->ops->write))
> return -EINVAL;
>
> @@ -1165,6 +1177,10 @@ static int vfio_device_fops_mmap(struct file *filep, struct vm_area_struct *vma)
> struct vfio_device_file *df = filep->private_data;
> struct vfio_device *device = df->device;
>
> + /* Paired with smp_store_release() following vfio_device_open() */
> + if (!smp_load_acquire(&df->access_granted))
> + return -EINVAL;
> +
> if (unlikely(!device->ops->mmap))
> return -EINVAL;
>
> @@ -1201,6 +1217,25 @@ bool vfio_file_is_valid(struct file *file)
> }
> EXPORT_SYMBOL_GPL(vfio_file_is_valid);
>
> +/*
> + * Return true if the input file is a vfio device file and has opened
> + * the input device. Otherwise, return false.
> + */
> +static bool vfio_file_has_device_access(struct file *file,
> + struct vfio_device *device)
> +{
> + struct vfio_device *vdev = vfio_device_from_file(file);
> + struct vfio_device_file *df;
> +
> + if (!vdev || vdev != device)
> + return false;
> +
> + df = file->private_data;
> +
> + /* Paired with smp_store_release() following vfio_device_open() */
> + return smp_load_acquire(&df->access_granted);
> +}
> +
> /**
> * vfio_file_has_dev - True if the VFIO file is a handle for device
> * @file: VFIO file to check
> @@ -1211,17 +1246,12 @@ EXPORT_SYMBOL_GPL(vfio_file_is_valid);
> bool vfio_file_has_dev(struct file *file, struct vfio_device *device)
> {
> struct vfio_group *group;
> - struct vfio_device *vdev;
>
> group = vfio_group_from_file(file);
> if (group)
> return vfio_group_has_dev(group, device);
>
> - vdev = vfio_device_from_file(file);
> - if (vdev)
> - return vdev == device;
> -
> - return false;
> + return vfio_file_has_device_access(file, device);
> }
> EXPORT_SYMBOL_GPL(vfio_file_has_dev);
>
next prev parent reply other threads:[~2023-04-06 14:08 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-01 15:18 [Intel-gfx] [PATCH v9 00/25] Add vfio_device cdev for iommufd support Yi Liu
2023-04-01 15:18 ` [Intel-gfx] [PATCH v9 01/25] vfio: Allocate per device file structure Yi Liu
2023-04-01 15:18 ` [Intel-gfx] [PATCH v9 02/25] vfio: Refine vfio file kAPIs for KVM Yi Liu
2023-04-01 15:18 ` [Intel-gfx] [PATCH v9 03/25] vfio: Remove vfio_file_is_group() Yi Liu
2023-04-05 12:20 ` Eric Auger
2023-04-01 15:18 ` [Intel-gfx] [PATCH v9 04/25] vfio: Accept vfio device file in the KVM facing kAPI Yi Liu
2023-04-05 17:58 ` Eric Auger
2023-04-01 15:18 ` [Intel-gfx] [PATCH v9 05/25] kvm/vfio: Rename kvm_vfio_group to prepare for accepting vfio device fd Yi Liu
2023-04-01 15:18 ` [Intel-gfx] [PATCH v9 06/25] kvm/vfio: Accept vfio device file from userspace Yi Liu
2023-04-06 9:46 ` Eric Auger
2023-04-06 10:49 ` Liu, Yi L
2023-04-06 18:57 ` Alex Williamson
2023-04-07 3:42 ` Liu, Yi L
2023-04-07 8:56 ` Eric Auger
2023-04-07 10:23 ` Liu, Yi L
2023-04-01 15:18 ` [Intel-gfx] [PATCH v9 07/25] vfio: Pass struct vfio_device_file * to vfio_device_open/close() Yi Liu
2023-04-06 12:43 ` Eric Auger
2023-04-01 15:18 ` [Intel-gfx] [PATCH v9 08/25] vfio: Block device access via device fd until device is opened Yi Liu
2023-04-06 14:08 ` Eric Auger [this message]
2023-04-01 15:18 ` [Intel-gfx] [PATCH v9 09/25] vfio: Add cdev_device_open_cnt to vfio_group Yi Liu
2023-04-06 14:13 ` Eric Auger
2023-04-01 15:18 ` [Intel-gfx] [PATCH v9 10/25] vfio: Make vfio_device_open() single open for device cdev path Yi Liu
2023-04-06 16:44 ` Eric Auger
2023-04-07 9:48 ` Eric Auger
2023-04-07 10:18 ` Liu, Yi L
2023-04-01 15:18 ` [Intel-gfx] [PATCH v9 11/25] vfio: Make vfio_device_first_open() to accept NULL iommufd for noiommu Yi Liu
2023-04-01 15:18 ` [Intel-gfx] [PATCH v9 12/25] vfio-iommufd: Move noiommu support out of vfio_iommufd_bind() Yi Liu
2023-04-01 15:18 ` [Intel-gfx] [PATCH v9 13/25] vfio-iommufd: Split bind/attach into two steps Yi Liu
2023-04-01 15:18 ` [Intel-gfx] [PATCH v9 14/25] vfio: Record devid in vfio_device_file Yi Liu
2023-04-01 15:18 ` [Intel-gfx] [PATCH v9 15/25] vfio-iommufd: Add detach_ioas support for physical VFIO devices Yi Liu
2023-04-01 15:18 ` [Intel-gfx] [PATCH v9 16/25] iommufd/device: Add iommufd_access_detach() API Yi Liu
2023-04-04 22:45 ` Alex Williamson
2023-04-05 11:56 ` Jason Gunthorpe
2023-04-05 14:10 ` Liu, Yi L
2023-04-05 14:28 ` Jason Gunthorpe
2023-04-05 14:46 ` Liu, Yi L
2023-04-01 15:18 ` [Intel-gfx] [PATCH v9 17/25] vfio-iommufd: Add detach_ioas support for emulated VFIO devices Yi Liu
2023-04-01 15:18 ` [Intel-gfx] [PATCH v9 18/25] vfio: Determine noiommu in vfio_device registration Yi Liu
2023-04-01 15:18 ` [Intel-gfx] [PATCH v9 19/25] vfio: Name noiommu vfio_device with "noiommu-" prefix Yi Liu
2023-04-01 15:18 ` [Intel-gfx] [PATCH v9 20/25] vfio: Move vfio_device_group_unregister() to be the first operation in unregister Yi Liu
2023-04-01 15:18 ` [Intel-gfx] [PATCH v9 21/25] vfio: Add cdev for vfio_device Yi Liu
2023-04-01 15:18 ` [Intel-gfx] [PATCH v9 22/25] vfio: Add VFIO_DEVICE_BIND_IOMMUFD Yi Liu
2023-04-01 15:18 ` [Intel-gfx] [PATCH v9 23/25] vfio: Add VFIO_DEVICE_[AT|DE]TACH_IOMMUFD_PT Yi Liu
2023-04-01 15:18 ` [Intel-gfx] [PATCH v9 24/25] vfio: Compile group optionally Yi Liu
2023-04-01 15:18 ` [Intel-gfx] [PATCH v9 25/25] docs: vfio: Add vfio device cdev description Yi Liu
2023-04-05 13:45 ` Eric Auger
2023-04-05 14:00 ` Liu, Yi L
2023-04-05 16:58 ` Alex Williamson
2023-04-07 8:44 ` Liu, Yi L
2023-04-01 15:23 ` [Intel-gfx] ✗ Fi.CI.BUILD: failure for Add vfio_device cdev for iommufd support (rev11) Patchwork
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=d8ebec5f-1742-2e51-8c6c-f02d46a6685f@redhat.com \
--to=eric.auger@redhat.com \
--cc=alex.williamson@redhat.com \
--cc=chao.p.peng@linux.intel.com \
--cc=cohuck@redhat.com \
--cc=intel-gfx@lists.freedesktop.org \
--cc=intel-gvt-dev@lists.freedesktop.org \
--cc=jasowang@redhat.com \
--cc=jgg@nvidia.com \
--cc=joro@8bytes.org \
--cc=kevin.tian@intel.com \
--cc=kvm@vger.kernel.org \
--cc=linux-s390@vger.kernel.org \
--cc=lulu@redhat.com \
--cc=mjrosato@linux.ibm.com \
--cc=nicolinc@nvidia.com \
--cc=peterx@redhat.com \
--cc=robin.murphy@arm.com \
--cc=shameerali.kolothum.thodi@huawei.com \
--cc=suravee.suthikulpanit@amd.com \
--cc=terrence.xu@intel.com \
--cc=xudong.hao@intel.com \
--cc=yan.y.zhao@intel.com \
--cc=yanting.jiang@intel.com \
--cc=yi.l.liu@intel.com \
--cc=yi.y.sun@linux.intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).