On 5/15/23 2:14 PM, Liu, Yi L wrote:
-----Original Message-----
From: Baolu Lu<baolu.lu@xxxxxxxxxxxxxxx>
Sent: Friday, May 12, 2023 1:39 PM
To: Liu, Yi L<yi.l.liu@xxxxxxxxx>;joro@xxxxxxxxxx;alex.williamson@xxxxxxxxxx;
jgg@xxxxxxxxxx; Tian, Kevin<kevin.tian@xxxxxxxxx>;robin.murphy@xxxxxxx
Cc:baolu.lu@xxxxxxxxxxxxxxx;cohuck@xxxxxxxxxx;eric.auger@xxxxxxxxxx;
nicolinc@xxxxxxxxxx;kvm@xxxxxxxxxxxxxxx;mjrosato@xxxxxxxxxxxxx;
chao.p.peng@xxxxxxxxxxxxxxx;yi.y.sun@xxxxxxxxxxxxxxx;peterx@xxxxxxxxxx;
jasowang@xxxxxxxxxx;shameerali.kolothum.thodi@xxxxxxxxxx;lulu@xxxxxxxxxx;
suravee.suthikulpanit@xxxxxxx;iommu@xxxxxxxxxxxxxxx;linux-kernel@xxxxxxxxxxxxxxx;
linux-kselftest@xxxxxxxxxxxxxxx; Duan, Zhenzhong<zhenzhong.duan@xxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: Nicolin Chen<nicolinc@xxxxxxxxxx>
Signed-off-by: Yi Liu<yi.l.liu@xxxxxxxxx>
---
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@xxxxxxxxxx/
Oh, I overlooked that. Thanks for the explanation. It's fair enough.
Best regards,
baolu
