[v3,3/4] iommufd: Add IOMMU_DEVICE_GET_HW_INFO
Commit Message
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@nvidia.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
---
drivers/iommu/iommufd/device.c | 72 +++++++++++++++++++++++++
drivers/iommu/iommufd/iommufd_private.h | 1 +
drivers/iommu/iommufd/main.c | 3 ++
include/uapi/linux/iommufd.h | 37 +++++++++++++
4 files changed, 113 insertions(+)
Comments
On 5/11/23 10:30 PM, 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@nvidia.com>
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
> ---
> drivers/iommu/iommufd/device.c | 72 +++++++++++++++++++++++++
> drivers/iommu/iommufd/iommufd_private.h | 1 +
> drivers/iommu/iommufd/main.c | 3 ++
> include/uapi/linux/iommufd.h | 37 +++++++++++++
> 4 files changed, 113 insertions(+)
>
> diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
> index 051bd8e99858..bc99d092de8f 100644
> --- a/drivers/iommu/iommufd/device.c
> +++ b/drivers/iommu/iommufd/device.c
> @@ -263,6 +263,78 @@ u32 iommufd_device_to_id(struct iommufd_device *idev)
> }
> EXPORT_SYMBOL_NS_GPL(iommufd_device_to_id, 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 *)u64_to_user_ptr(ptr + index)))
> + return -EFAULT;
> + }
> + return 0;
> +}
> +
> +int iommufd_device_get_hw_info(struct iommufd_ucmd *ucmd)
> +{
> + struct iommu_hw_info *cmd = ucmd->cmd;
> + unsigned int length = 0, data_len;
> + struct iommufd_device *idev;
> + const struct iommu_ops *ops;
> + void *data = NULL;
> + int rc = 0;
> +
> + 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->hw_info)
> + goto done;
If the iommu driver doesn't provide a hw_info callback, it still
returns success?
> +
> + /* driver has hw_info callback should have a unique hw_info_type */
> + if (ops->hw_info_type == IOMMU_HW_INFO_TYPE_NONE) {
> + pr_warn_ratelimited("iommu driver set an invalid type\n");
> + rc = -ENODEV;
> + goto out_err;
> + }
> +
> + data = ops->hw_info(idev->dev, &data_len);
> + if (IS_ERR(data)) {
> + rc = PTR_ERR(data);
> + goto out_err;
> + }
> +
> + length = min(cmd->data_len, data_len);
> + if (copy_to_user(u64_to_user_ptr(cmd->data_ptr), data, length)) {
> + rc = -EFAULT;
> + goto out_err;
> + }
> +
> + /*
> + * 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_err;
> + }
> +
> +done:
> + cmd->data_len = length;
> + cmd->out_data_type = ops->hw_info_type;
> + rc = iommufd_ucmd_respond(ucmd, sizeof(*cmd));
> +
> +out_err:
> + kfree(data);
> + iommufd_put_object(&idev->obj);
> + return rc;
> +}
> +
> static int iommufd_group_setup_msi(struct iommufd_group *igroup,
> struct iommufd_hw_pagetable *hwpt)
> {
Best regards,
baolu
> -----Original Message-----
> From: Baolu Lu <baolu.lu@linux.intel.com>
> Sent: Friday, May 12, 2023 1:39 PM
> To: Liu, Yi L <yi.l.liu@intel.com>; joro@8bytes.org; alex.williamson@redhat.com;
> jgg@nvidia.com; Tian, Kevin <kevin.tian@intel.com>; robin.murphy@arm.com
> Cc: baolu.lu@linux.intel.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; iommu@lists.linux.dev; linux-kernel@vger.kernel.org;
> linux-kselftest@vger.kernel.org; Duan, Zhenzhong <zhenzhong.duan@intel.com>
> Subject: Re: [PATCH v3 3/4] iommufd: Add IOMMU_DEVICE_GET_HW_INFO
>
> On 5/11/23 10:30 PM, 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@nvidia.com>
> > Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> > Signed-off-by: Yi Liu <yi.l.liu@intel.com>
> > ---
> > drivers/iommu/iommufd/device.c | 72 +++++++++++++++++++++++++
> > drivers/iommu/iommufd/iommufd_private.h | 1 +
> > drivers/iommu/iommufd/main.c | 3 ++
> > include/uapi/linux/iommufd.h | 37 +++++++++++++
> > 4 files changed, 113 insertions(+)
> >
> > diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
> > index 051bd8e99858..bc99d092de8f 100644
> > --- a/drivers/iommu/iommufd/device.c
> > +++ b/drivers/iommu/iommufd/device.c
> > @@ -263,6 +263,78 @@ u32 iommufd_device_to_id(struct iommufd_device *idev)
> > }
> > EXPORT_SYMBOL_NS_GPL(iommufd_device_to_id, 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 *)u64_to_user_ptr(ptr + index)))
> > + return -EFAULT;
> > + }
> > + return 0;
> > +}
> > +
> > +int iommufd_device_get_hw_info(struct iommufd_ucmd *ucmd)
> > +{
> > + struct iommu_hw_info *cmd = ucmd->cmd;
> > + unsigned int length = 0, data_len;
> > + struct iommufd_device *idev;
> > + const struct iommu_ops *ops;
> > + void *data = NULL;
> > + int rc = 0;
> > +
> > + 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->hw_info)
> > + goto done;
>
> If the iommu driver doesn't provide a hw_info callback, it still
> returns success?
Yes, as noted in the cover letter. It's for a remark from Jason. In such
case, the out_data_type is NULL, it means no specific data is filled
in the buffer pointed by cmd->data_ptr.
- Let IOMMU_DEVICE_GET_HW_INFO succeed even the underlying iommu driver
does not have driver-specific data to report per below remark.
https://lore.kernel.org/kvm/ZAcwJSK%2F9UVI9LXu@nvidia.com/
Regards,
Yi Liu
> > +
> > + /* driver has hw_info callback should have a unique hw_info_type */
> > + if (ops->hw_info_type == IOMMU_HW_INFO_TYPE_NONE) {
> > + pr_warn_ratelimited("iommu driver set an invalid type\n");
> > + rc = -ENODEV;
> > + goto out_err;
> > + }
> > +
> > + data = ops->hw_info(idev->dev, &data_len);
> > + if (IS_ERR(data)) {
> > + rc = PTR_ERR(data);
> > + goto out_err;
> > + }
> > +
> > + length = min(cmd->data_len, data_len);
> > + if (copy_to_user(u64_to_user_ptr(cmd->data_ptr), data, length)) {
> > + rc = -EFAULT;
> > + goto out_err;
> > + }
> > +
> > + /*
> > + * 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_err;
> > + }
> > +
> > +done:
> > + cmd->data_len = length;
> > + cmd->out_data_type = ops->hw_info_type;
> > + rc = iommufd_ucmd_respond(ucmd, sizeof(*cmd));
> > +
> > +out_err:
> > + kfree(data);
> > + iommufd_put_object(&idev->obj);
> > + return rc;
> > +}
> > +
> > static int iommufd_group_setup_msi(struct iommufd_group *igroup,
> > struct iommufd_hw_pagetable *hwpt)
> > {
>
> Best regards,
> baolu
On 5/15/23 2:14 PM, Liu, Yi L wrote:
>> -----Original Message-----
>> From: Baolu Lu<baolu.lu@linux.intel.com>
>> Sent: Friday, May 12, 2023 1:39 PM
>> To: Liu, Yi L<yi.l.liu@intel.com>;joro@8bytes.org;alex.williamson@redhat.com;
>> jgg@nvidia.com; Tian, Kevin<kevin.tian@intel.com>;robin.murphy@arm.com
>> Cc:baolu.lu@linux.intel.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;iommu@lists.linux.dev;linux-kernel@vger.kernel.org;
>> linux-kselftest@vger.kernel.org; Duan, Zhenzhong<zhenzhong.duan@intel.com>
>> Subject: Re: [PATCH v3 3/4] iommufd: Add IOMMU_DEVICE_GET_HW_INFO
>>
>> On 5/11/23 10:30 PM, 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@nvidia.com>
>>> Signed-off-by: Nicolin Chen<nicolinc@nvidia.com>
>>> Signed-off-by: Yi Liu<yi.l.liu@intel.com>
>>> ---
>>> drivers/iommu/iommufd/device.c | 72 +++++++++++++++++++++++++
>>> drivers/iommu/iommufd/iommufd_private.h | 1 +
>>> drivers/iommu/iommufd/main.c | 3 ++
>>> include/uapi/linux/iommufd.h | 37 +++++++++++++
>>> 4 files changed, 113 insertions(+)
>>>
>>> diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
>>> index 051bd8e99858..bc99d092de8f 100644
>>> --- a/drivers/iommu/iommufd/device.c
>>> +++ b/drivers/iommu/iommufd/device.c
>>> @@ -263,6 +263,78 @@ u32 iommufd_device_to_id(struct iommufd_device *idev)
>>> }
>>> EXPORT_SYMBOL_NS_GPL(iommufd_device_to_id, 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 *)u64_to_user_ptr(ptr + index)))
>>> + return -EFAULT;
>>> + }
>>> + return 0;
>>> +}
>>> +
>>> +int iommufd_device_get_hw_info(struct iommufd_ucmd *ucmd)
>>> +{
>>> + struct iommu_hw_info *cmd = ucmd->cmd;
>>> + unsigned int length = 0, data_len;
>>> + struct iommufd_device *idev;
>>> + const struct iommu_ops *ops;
>>> + void *data = NULL;
>>> + int rc = 0;
>>> +
>>> + 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->hw_info)
>>> + goto done;
>> If the iommu driver doesn't provide a hw_info callback, it still
>> returns success?
> Yes, as noted in the cover letter. It's for a remark from Jason. In such
> case, the out_data_type is NULL, it means no specific data is filled
> in the buffer pointed by cmd->data_ptr.
>
> - Let IOMMU_DEVICE_GET_HW_INFO succeed even the underlying iommu driver
> does not have driver-specific data to report per below remark.
> https://lore.kernel.org/kvm/ZAcwJSK%2F9UVI9LXu@nvidia.com/
Oh, I overlooked that. Thanks for the explanation. It's fair enough.
Best regards,
baolu
> From: Liu, Yi L <yi.l.liu@intel.com>
> Sent: Thursday, May 11, 2023 10:30 PM
> +
> +int iommufd_device_get_hw_info(struct iommufd_ucmd *ucmd)
> +{
> + struct iommu_hw_info *cmd = ucmd->cmd;
> + unsigned int length = 0, data_len;
> + struct iommufd_device *idev;
> + const struct iommu_ops *ops;
> + void *data = NULL;
> + int rc = 0;
> +
> + 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->hw_info)
> + goto done;
> +
> + /* driver has hw_info callback should have a unique hw_info_type */
> + if (ops->hw_info_type == IOMMU_HW_INFO_TYPE_NONE) {
> + pr_warn_ratelimited("iommu driver set an invalid type\n");
> + rc = -ENODEV;
> + goto out_err;
> + }
this should be a WARN_ON_ONCE() since it's a driver bug.
> +
> + data = ops->hw_info(idev->dev, &data_len);
> + if (IS_ERR(data)) {
> + rc = PTR_ERR(data);
> + goto out_err;
> + }
> +
> + length = min(cmd->data_len, data_len);
> + if (copy_to_user(u64_to_user_ptr(cmd->data_ptr), data, length)) {
> + rc = -EFAULT;
> + goto out_err;
> + }
> +
> + /*
> + * 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_err;
> + }
> +
> +done:
> + cmd->data_len = length;
> + cmd->out_data_type = ops->hw_info_type;
> + rc = iommufd_ucmd_respond(ucmd, sizeof(*cmd));
the 'done' label should be moved before above zero_fill. Otherwise
in !ops->hw_info case the user buffer is not cleared.
> union ucmd_buffer {
> struct iommu_destroy destroy;
> struct iommu_hwpt_alloc hwpt;
> + struct iommu_hw_info info;
follow alphabetic order this should be ahead of hwpt.
> @@ -302,6 +303,8 @@ 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),
before IOMMU_HWPT_ALLOC
> +
> +/**
> + * struct iommu_hw_info - ioctl(IOMMU_DEVICE_GET_HW_INFO)
> + * @size: sizeof(struct iommu_hw_info)
> + * @flags: Must be 0
> + * @dev_id: The device bound to the iommufd
> + * @data_len: Input the length of the user buffer in bytes. Output the
> + * length of data filled in the user buffer.
> + * @data_ptr: Pointer to the user buffer
> + * @out_data_type: Output the iommu hardware info type as defined by
> + * 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
> + * virtual IOMMU and the hardware IOMMU. e.g. nested translation
> requires
> + * to check the hardware IOMMU capability so guest stage-1 page table
> + * uses a format compatible to the 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.
> + */
> +struct iommu_hw_info {
> + __u32 size;
> + __u32 flags;
> + __u32 dev_id;
> + __u32 data_len;
> + __aligned_u64 data_ptr;
> + __u32 out_data_type;
> + __u32 __reserved;
it's unusual to have reserved field in the end. It makes more sense
to move data_ptr to the end to make it meaningful.
> +};
> +#define IOMMU_DEVICE_GET_HW_INFO _IO(IOMMUFD_TYPE,
> IOMMUFD_CMD_DEVICE_GET_HW_INFO)
> #endif
Here we have a naming confusion.
'IOMMU' is the prefix of iommufd ioctls.
'DEVICE' is the subjective.
Then "GET_HW_INFO" implies getting hardware info related to
this device. then it should not be restricted to the iommu info.
with that it's clearer to call it IOMMU_DEVICE_GET_IOMMU_INFO.
similarly for struct iommu_hw_info.
'iommu' is the prefix for all iommufd ioctl structures.
then 'hw_info' is too broard.
iommu_device_iommu_info reads better? though having two
iommu's in the name is a little bit annoying...
> From: Tian, Kevin
> Sent: Friday, May 19, 2023 4:42 PM
> > +struct iommu_hw_info {
> > + __u32 size;
> > + __u32 flags;
> > + __u32 dev_id;
> > + __u32 data_len;
> > + __aligned_u64 data_ptr;
> > + __u32 out_data_type;
> > + __u32 __reserved;
>
> it's unusual to have reserved field in the end. It makes more sense
> to move data_ptr to the end to make it meaningful.
>
Please ignore this comment. typed too fast...
Hi Kevin,
On Fri, May 19, 2023 at 08:42:07AM +0000, Tian, Kevin wrote:
> > +};
> > +#define IOMMU_DEVICE_GET_HW_INFO _IO(IOMMUFD_TYPE,
> > IOMMUFD_CMD_DEVICE_GET_HW_INFO)
> > #endif
>
> Here we have a naming confusion.
>
> 'IOMMU' is the prefix of iommufd ioctls.
>
> 'DEVICE' is the subjective.
>
> Then "GET_HW_INFO" implies getting hardware info related to
> this device. then it should not be restricted to the iommu info.
>
> with that it's clearer to call it IOMMU_DEVICE_GET_IOMMU_INFO.
Though the entire ioctl is tied to the input "dev_id", I think
it isn't really about the device corresponding to the dev_id,
similar to the IOMMU_HWPT_ALLOC having a dev_id input too. So,
I think the "IOMMU_DEVICE" here should be interpreted simply
as "an iommu device". We could also highlight this somewhere
in the header.
With that being said, IOMMU_DEVICE_SET/UNSET_DATA should be
renamed to IOMMU_DEVICE_SET/UNSET_DEV_DATA -- "DEVICE" is the
iommu device while the "DEV_DATA" is a given device that's
behind the iommu.
> similarly for struct iommu_hw_info.
>
> 'iommu' is the prefix for all iommufd ioctl structures.
>
> then 'hw_info' is too broard.
>
> iommu_device_iommu_info reads better? though having two
> iommu's in the name is a little bit annoying...
How about:
IOMMU_DEVICE_GET_FEATURES
struct iommu_device_features
?
Thanks
Nic
> From: Nicolin Chen <nicolinc@nvidia.com>
> Sent: Saturday, May 20, 2023 2:30 AM
>
> Hi Kevin,
>
> On Fri, May 19, 2023 at 08:42:07AM +0000, Tian, Kevin wrote:
>
> > > +};
> > > +#define IOMMU_DEVICE_GET_HW_INFO _IO(IOMMUFD_TYPE,
> > > IOMMUFD_CMD_DEVICE_GET_HW_INFO)
> > > #endif
> >
> > Here we have a naming confusion.
> >
> > 'IOMMU' is the prefix of iommufd ioctls.
> >
> > 'DEVICE' is the subjective.
> >
> > Then "GET_HW_INFO" implies getting hardware info related to
> > this device. then it should not be restricted to the iommu info.
> >
> > with that it's clearer to call it IOMMU_DEVICE_GET_IOMMU_INFO.
>
> Though the entire ioctl is tied to the input "dev_id", I think
> it isn't really about the device corresponding to the dev_id,
> similar to the IOMMU_HWPT_ALLOC having a dev_id input too. So,
> I think the "IOMMU_DEVICE" here should be interpreted simply
> as "an iommu device". We could also highlight this somewhere
> in the header.
yes this is a good view of it. with that it's not necessary to have
a 'DEVICE' notation in the name which looks confusing with dev_id.
Just IOMMU_GET_HW_INFO for the iommu behind the specified dev_id.
then keep the structure name as iommu_hw_info.
>
> With that being said, IOMMU_DEVICE_SET/UNSET_DATA should be
> renamed to IOMMU_DEVICE_SET/UNSET_DEV_DATA -- "DEVICE" is the
> iommu device while the "DEV_DATA" is a given device that's
> behind the iommu.
this then becomes IOMMU_SET/UNSET_DEV_DATA.
>
> > similarly for struct iommu_hw_info.
> >
> > 'iommu' is the prefix for all iommufd ioctl structures.
> >
> > then 'hw_info' is too broard.
> >
> > iommu_device_iommu_info reads better? though having two
> > iommu's in the name is a little bit annoying...
>
> How about:
> IOMMU_DEVICE_GET_FEATURES
> struct iommu_device_features
> ?
>
> Thanks
> Nic
On Wed, May 24, 2023 at 05:00:40AM +0000, Tian, Kevin wrote:
> > > > +};
> > > > +#define IOMMU_DEVICE_GET_HW_INFO _IO(IOMMUFD_TYPE,
> > > > IOMMUFD_CMD_DEVICE_GET_HW_INFO)
> > > > #endif
> > >
> > > Here we have a naming confusion.
> > >
> > > 'IOMMU' is the prefix of iommufd ioctls.
> > >
> > > 'DEVICE' is the subjective.
> > >
> > > Then "GET_HW_INFO" implies getting hardware info related to
> > > this device. then it should not be restricted to the iommu info.
> > >
> > > with that it's clearer to call it IOMMU_DEVICE_GET_IOMMU_INFO.
> >
> > Though the entire ioctl is tied to the input "dev_id", I think
> > it isn't really about the device corresponding to the dev_id,
> > similar to the IOMMU_HWPT_ALLOC having a dev_id input too. So,
> > I think the "IOMMU_DEVICE" here should be interpreted simply
> > as "an iommu device". We could also highlight this somewhere
> > in the header.
>
> yes this is a good view of it. with that it's not necessary to have
> a 'DEVICE' notation in the name which looks confusing with dev_id.
>
> Just IOMMU_GET_HW_INFO for the iommu behind the specified dev_id.
>
> then keep the structure name as iommu_hw_info.
That'd be neat.
> > With that being said, IOMMU_DEVICE_SET/UNSET_DATA should be
> > renamed to IOMMU_DEVICE_SET/UNSET_DEV_DATA -- "DEVICE" is the
> > iommu device while the "DEV_DATA" is a given device that's
> > behind the iommu.
>
> this then becomes IOMMU_SET/UNSET_DEV_DATA.
Ack.
Thanks
Nic
@@ -263,6 +263,78 @@ u32 iommufd_device_to_id(struct iommufd_device *idev)
}
EXPORT_SYMBOL_NS_GPL(iommufd_device_to_id, 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 *)u64_to_user_ptr(ptr + index)))
+ return -EFAULT;
+ }
+ return 0;
+}
+
+int iommufd_device_get_hw_info(struct iommufd_ucmd *ucmd)
+{
+ struct iommu_hw_info *cmd = ucmd->cmd;
+ unsigned int length = 0, data_len;
+ struct iommufd_device *idev;
+ const struct iommu_ops *ops;
+ void *data = NULL;
+ int rc = 0;
+
+ 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->hw_info)
+ goto done;
+
+ /* driver has hw_info callback should have a unique hw_info_type */
+ if (ops->hw_info_type == IOMMU_HW_INFO_TYPE_NONE) {
+ pr_warn_ratelimited("iommu driver set an invalid type\n");
+ rc = -ENODEV;
+ goto out_err;
+ }
+
+ data = ops->hw_info(idev->dev, &data_len);
+ if (IS_ERR(data)) {
+ rc = PTR_ERR(data);
+ goto out_err;
+ }
+
+ length = min(cmd->data_len, data_len);
+ if (copy_to_user(u64_to_user_ptr(cmd->data_ptr), data, length)) {
+ rc = -EFAULT;
+ goto out_err;
+ }
+
+ /*
+ * 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_err;
+ }
+
+done:
+ cmd->data_len = length;
+ cmd->out_data_type = ops->hw_info_type;
+ rc = iommufd_ucmd_respond(ucmd, sizeof(*cmd));
+
+out_err:
+ kfree(data);
+ iommufd_put_object(&idev->obj);
+ return rc;
+}
+
static int iommufd_group_setup_msi(struct iommufd_group *igroup,
struct iommufd_hw_pagetable *hwpt)
{
@@ -308,6 +308,7 @@ 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;
@@ -269,6 +269,7 @@ 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;
@@ -302,6 +303,8 @@ 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,
@@ -46,6 +46,7 @@ enum {
IOMMUFD_CMD_OPTION,
IOMMUFD_CMD_VFIO_IOAS,
IOMMUFD_CMD_HWPT_ALLOC,
+ IOMMUFD_CMD_DEVICE_GET_HW_INFO,
};
/**
@@ -377,4 +378,40 @@ struct iommu_hwpt_alloc {
enum iommu_hw_info_type {
IOMMU_HW_INFO_TYPE_NONE,
};
+
+/**
+ * struct iommu_hw_info - ioctl(IOMMU_DEVICE_GET_HW_INFO)
+ * @size: sizeof(struct iommu_hw_info)
+ * @flags: Must be 0
+ * @dev_id: The device bound to the iommufd
+ * @data_len: Input the length of the user buffer in bytes. Output the
+ * length of data filled in the user buffer.
+ * @data_ptr: Pointer to the user buffer
+ * @out_data_type: Output the iommu hardware info type as defined by
+ * 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
+ * virtual IOMMU and the hardware IOMMU. e.g. nested translation requires
+ * to check the hardware IOMMU capability so guest stage-1 page table
+ * uses a format compatible to the 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.
+ */
+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