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Message-ID: <6c1b221e-df8d-4b82-10e5-aa3027819d45@linux.intel.com>
Date: Thu, 9 Mar 2023 21:50:18 +0800
From: Baolu Lu <baolu.lu@...ux.intel.com>
To: Yi Liu <yi.l.liu@...el.com>, joro@...tes.org,
alex.williamson@...hat.com, jgg@...dia.com, kevin.tian@...el.com,
robin.murphy@....com
Cc: baolu.lu@...ux.intel.com, cohuck@...hat.com, eric.auger@...hat.com,
nicolinc@...dia.com, kvm@...r.kernel.org, mjrosato@...ux.ibm.com,
chao.p.peng@...ux.intel.com, yi.y.sun@...ux.intel.com,
peterx@...hat.com, jasowang@...hat.com,
shameerali.kolothum.thodi@...wei.com, lulu@...hat.com,
suravee.suthikulpanit@....com, iommu@...ts.linux.dev,
linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH v2 3/4] iommufd: Add IOMMU_DEVICE_GET_HW_INFO
On 2023/3/9 15:53, Yi Liu wrote:
> Under nested IOMMU translation, userspace owns the stage-1 translation
> table (e.g. the stage-1 page table of Intel VT-d or the context table
> of ARM SMMUv3, and etc.). Stage-1 translation tables are vendor specific,
> and needs to be compatiable with the underlying IOMMU hardware. Hence,
> userspace should know the IOMMU hardware capability before creating and
> configuring the stage-1 translation table to kernel.
>
> This adds IOMMU_DEVICE_GET_HW_INFO to query the IOMMU hardware information
> for a given device. The returned data is vendor specific, userspace needs
> to decode it with the structure mapped by the @out_data_type field.
>
> As only physical devices have IOMMU hardware, so this will return error
> if the given device is not a physical device.
>
> Co-developed-by: Nicolin Chen <nicolinc@...dia.com>
> Signed-off-by: Nicolin Chen <nicolinc@...dia.com>
> Signed-off-by: Yi Liu <yi.l.liu@...el.com>
> ---
> drivers/iommu/iommufd/device.c | 74 +++++++++++++++++++++++++
> drivers/iommu/iommufd/iommufd_private.h | 1 +
> drivers/iommu/iommufd/main.c | 3 +
> include/uapi/linux/iommufd.h | 40 +++++++++++++
> 4 files changed, 118 insertions(+)
>
> diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
> index c10e02f6a0be..6948539488a5 100644
> --- a/drivers/iommu/iommufd/device.c
> +++ b/drivers/iommu/iommufd/device.c
> @@ -257,6 +257,80 @@ struct iommufd_ctx *iommufd_device_to_ictx(struct iommufd_device *idev)
> }
> EXPORT_SYMBOL_NS_GPL(iommufd_device_to_ictx, IOMMUFD);
>
> +static int iommufd_zero_fill_user(u64 ptr, int bytes)
> +{
> + int index = 0;
> +
> + for (; index < bytes; index++) {
> + if (put_user(0, (uint8_t __user *)(ptr + index)))
> + return -EFAULT;
> + }
> + return 0;
> +}
> +
> +int iommufd_device_get_hw_info(struct iommufd_ucmd *ucmd)
> +{
> + struct iommu_hw_info *cmd = ucmd->cmd;
> + struct iommufd_device *idev;
> + const struct iommu_ops *ops;
> + void *data;
> + unsigned int length, data_len;
> + int rc;
Reverse christmas tree order for declarations.
> +
> + if (cmd->flags || cmd->__reserved || !cmd->data_len)
> + return -EOPNOTSUPP;
> +
> + idev = iommufd_get_device(ucmd, cmd->dev_id);
> + if (IS_ERR(idev))
> + return PTR_ERR(idev);
> +
> + ops = dev_iommu_ops(idev->dev);
> + if (!ops || !ops->hw_info) {
dev_iommu_ops() will never return a NULL.
Need below check
dev->iommu && dev->iommu->iommu_dev
before dev_iommu_ops(). Perhaps something like below?
if (!dev->iommu || !dev->iommu->iommu_dev)
return -EINVAL;
ops = dev_iommu_ops(idev->dev);
if (!ops->hw_info)
return -ENODEV;
> + rc = -EOPNOTSUPP;
> + goto out_put;
> + }
> +
> + /* driver has hw_info callback should have a unique driver_type */
> + if (WARN_ON(ops->driver_type == IOMMU_HW_INFO_TYPE_DEFAULT)) {
If so, perhaps IOMMU_HW_INFO_TYPE_INVALID is more readable?
I'm not sure if a calltrace is really necessary here. If not, perhaps,
if (ops->driver_type == IOMMU_HW_INFO_TYPE_DEFAULT) {
pr_warn_ratelimited("iommu driver set an invalid type\n");
rc = -ENODEV;
goto out_put;
}
> + rc = -EOPNOTSUPP;
> + goto out_put;
> + }
> +
> + data = ops->hw_info(idev->dev, &data_len);
> + if (IS_ERR(data)) {
> + rc = PTR_ERR(data);
> + goto out_put;
> + }
> +
> + length = min(cmd->data_len, data_len);
> + if (copy_to_user(u64_to_user_ptr(cmd->data_ptr), data, length)) {
> + rc = -EFAULT;
> + goto out_free_data;
> + }
> +
> + /*
> + * Zero the trailing bytes if the user buffer is bigger than the
> + * data size kernel actually has.
> + */
> + if (length < cmd->data_len) {
> + rc = iommufd_zero_fill_user(cmd->data_ptr + length,
> + cmd->data_len - length);
> + if (rc)
> + goto out_free_data;
> + }
> +
> + cmd->out_data_type = ops->driver_type;
> + cmd->data_len = length;
> +
> + rc = iommufd_ucmd_respond(ucmd, sizeof(*cmd));
> +
> +out_free_data:
> + kfree(data);
> +out_put:
> + iommufd_put_object(&idev->obj);
> + return rc;
> +}
> +
> static int iommufd_group_setup_msi(struct iommufd_group *igroup,
> struct iommufd_hw_pagetable *hwpt)
> {
> diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
> index b18f843ad6a4..05b5ad66f716 100644
> --- a/drivers/iommu/iommufd/iommufd_private.h
> +++ b/drivers/iommu/iommufd/iommufd_private.h
> @@ -307,6 +307,7 @@ iommufd_get_device(struct iommufd_ucmd *ucmd, u32 id)
> }
>
> void iommufd_device_destroy(struct iommufd_object *obj);
> +int iommufd_device_get_hw_info(struct iommufd_ucmd *ucmd);
>
> struct iommufd_access {
> struct iommufd_object obj;
> diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c
> index 694da191e4b1..f079c0bda46b 100644
> --- a/drivers/iommu/iommufd/main.c
> +++ b/drivers/iommu/iommufd/main.c
> @@ -262,6 +262,7 @@ static int iommufd_option(struct iommufd_ucmd *ucmd)
> union ucmd_buffer {
> struct iommu_destroy destroy;
> struct iommu_hwpt_alloc hwpt;
> + struct iommu_hw_info info;
> struct iommu_ioas_alloc alloc;
> struct iommu_ioas_allow_iovas allow_iovas;
> struct iommu_ioas_copy ioas_copy;
> @@ -295,6 +296,8 @@ static const struct iommufd_ioctl_op iommufd_ioctl_ops[] = {
> IOCTL_OP(IOMMU_DESTROY, iommufd_destroy, struct iommu_destroy, id),
> IOCTL_OP(IOMMU_HWPT_ALLOC, iommufd_hwpt_alloc, struct iommu_hwpt_alloc,
> __reserved),
> + IOCTL_OP(IOMMU_DEVICE_GET_HW_INFO, iommufd_device_get_hw_info,
> + struct iommu_hw_info, __reserved),
> IOCTL_OP(IOMMU_IOAS_ALLOC, iommufd_ioas_alloc_ioctl,
> struct iommu_ioas_alloc, out_ioas_id),
> IOCTL_OP(IOMMU_IOAS_ALLOW_IOVAS, iommufd_ioas_allow_iovas,
> diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
> index 955cbef640da..4ac525897b82 100644
> --- a/include/uapi/linux/iommufd.h
> +++ b/include/uapi/linux/iommufd.h
> @@ -46,6 +46,7 @@ enum {
> IOMMUFD_CMD_OPTION,
> IOMMUFD_CMD_VFIO_IOAS,
> IOMMUFD_CMD_HWPT_ALLOC,
> + IOMMUFD_CMD_DEVICE_GET_HW_INFO,
> };
>
> /**
> @@ -377,4 +378,43 @@ struct iommu_hwpt_alloc {
> enum iommu_hw_info_type {
> IOMMU_HW_INFO_TYPE_DEFAULT,
> };
> +
> +/**
> + * struct iommu_hw_info - ioctl(IOMMU_DEVICE_GET_HW_INFO)
> + * @size: sizeof(struct iommu_hw_info)
> + * @flags: Must be 0
> + * @dev_id: The device being attached to the iommufd
> + * @data_len: Input the length of the user buffer in bytes. Output the
> + * length of data filled to the user buffer.
> + * @data_ptr: Pointer to the type specific structure
> + * @out_data_type: Output the iommu hardware info type, it is one of
> + * enum iommu_hw_info_type.
> + * @__reserved: Must be 0
> + *
> + * Query the hardware iommu information for given device which has been
> + * bound to iommufd. @data_len is the size of the buffer which captures
> + * iommu type specific data and the data will be filled. Trailing bytes
> + * are zeroed if the user buffer is larger than the data kernel has.
> + *
> + * The type specific data would be used to sync capability between the
> + * vIOMMU and the hardware IOMMU. e.g. nested translation requires to
> + * check the hardware IOMMU capability, since a stage-1 translation table
> + * is owned by user but used by hardware IOMMU.
> + *
> + * The @out_data_type will be filled if the ioctl succeeds. It would
> + * be used to decode the data filled in the buffer pointed by @data_ptr.
> + *
> + * This is only available for the physical devices bound to iommufd as
> + * only physical devices can have hardware IOMMU.
> + */
> +struct iommu_hw_info {
> + __u32 size;
> + __u32 flags;
> + __u32 dev_id;
> + __u32 data_len;
> + __aligned_u64 data_ptr;
> + __u32 out_data_type;
> + __u32 __reserved;
> +};
> +#define IOMMU_DEVICE_GET_HW_INFO _IO(IOMMUFD_TYPE, IOMMUFD_CMD_DEVICE_GET_HW_INFO)
> #endif
Other look good to me.
Best regards,
baolu
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