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SubjectRe: [PATCH v8 5/9] hisi_acc_vfio_pci: Restrict access to VF dev BAR2 migration region
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On 2022/3/4 7:01, Shameer Kolothum wrote:
> HiSilicon ACC VF device BAR2 region consists of both functional
> register space and migration control register space. From a
> security point of view, it's not advisable to export the migration
> control region to Guest.
>
> Hence, introduce a separate struct vfio_device_ops for migration
> support which will override the ioctl/read/write/mmap methods to
> hide the migration region and limit the access only to the
> functional register space.
>
> This will be used in subsequent patches when we add migration
> support to the driver.
>
> Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Reviewed-by: Longfang Liu <liulongfang@huawei.com>

Thanks,
Longfang
> ---
> .../vfio/pci/hisilicon/hisi_acc_vfio_pci.c | 126 ++++++++++++++++++
> 1 file changed, 126 insertions(+)
>
> diff --git a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
> index 8129c3457b3b..582ee4fa4109 100644
> --- a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
> +++ b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
> @@ -13,6 +13,119 @@
> #include <linux/vfio.h>
> #include <linux/vfio_pci_core.h>
>
> +static int hisi_acc_pci_rw_access_check(struct vfio_device *core_vdev,
> + size_t count, loff_t *ppos,
> + size_t *new_count)
> +{
> + unsigned int index = VFIO_PCI_OFFSET_TO_INDEX(*ppos);
> + struct vfio_pci_core_device *vdev =
> + container_of(core_vdev, struct vfio_pci_core_device, vdev);
> +
> + if (index == VFIO_PCI_BAR2_REGION_INDEX) {
> + loff_t pos = *ppos & VFIO_PCI_OFFSET_MASK;
> + resource_size_t end = pci_resource_len(vdev->pdev, index) / 2;
> +
> + /* Check if access is for migration control region */
> + if (pos >= end)
> + return -EINVAL;
> +
> + *new_count = min(count, (size_t)(end - pos));
> + }
> +
> + return 0;
> +}
> +
> +static int hisi_acc_vfio_pci_mmap(struct vfio_device *core_vdev,
> + struct vm_area_struct *vma)
> +{
> + struct vfio_pci_core_device *vdev =
> + container_of(core_vdev, struct vfio_pci_core_device, vdev);
> + unsigned int index;
> +
> + index = vma->vm_pgoff >> (VFIO_PCI_OFFSET_SHIFT - PAGE_SHIFT);
> + if (index == VFIO_PCI_BAR2_REGION_INDEX) {
> + u64 req_len, pgoff, req_start;
> + resource_size_t end = pci_resource_len(vdev->pdev, index) / 2;
> +
> + req_len = vma->vm_end - vma->vm_start;
> + pgoff = vma->vm_pgoff &
> + ((1U << (VFIO_PCI_OFFSET_SHIFT - PAGE_SHIFT)) - 1);
> + req_start = pgoff << PAGE_SHIFT;
> +
> + if (req_start + req_len > end)
> + return -EINVAL;
> + }
> +
> + return vfio_pci_core_mmap(core_vdev, vma);
> +}
> +
> +static ssize_t hisi_acc_vfio_pci_write(struct vfio_device *core_vdev,
> + const char __user *buf, size_t count,
> + loff_t *ppos)
> +{
> + size_t new_count = count;
> + int ret;
> +
> + ret = hisi_acc_pci_rw_access_check(core_vdev, count, ppos, &new_count);
> + if (ret)
> + return ret;
> +
> + return vfio_pci_core_write(core_vdev, buf, new_count, ppos);
> +}
> +
> +static ssize_t hisi_acc_vfio_pci_read(struct vfio_device *core_vdev,
> + char __user *buf, size_t count,
> + loff_t *ppos)
> +{
> + size_t new_count = count;
> + int ret;
> +
> + ret = hisi_acc_pci_rw_access_check(core_vdev, count, ppos, &new_count);
> + if (ret)
> + return ret;
> +
> + return vfio_pci_core_read(core_vdev, buf, new_count, ppos);
> +}
> +
> +static long hisi_acc_vfio_pci_ioctl(struct vfio_device *core_vdev, unsigned int cmd,
> + unsigned long arg)
> +{
> + if (cmd == VFIO_DEVICE_GET_REGION_INFO) {
> + struct vfio_pci_core_device *vdev =
> + container_of(core_vdev, struct vfio_pci_core_device, vdev);
> + struct pci_dev *pdev = vdev->pdev;
> + struct vfio_region_info info;
> + unsigned long minsz;
> +
> + minsz = offsetofend(struct vfio_region_info, offset);
> +
> + if (copy_from_user(&info, (void __user *)arg, minsz))
> + return -EFAULT;
> +
> + if (info.argsz < minsz)
> + return -EINVAL;
> +
> + if (info.index == VFIO_PCI_BAR2_REGION_INDEX) {
> + info.offset = VFIO_PCI_INDEX_TO_OFFSET(info.index);
> +
> + /*
> + * ACC VF dev BAR2 region consists of both functional
> + * register space and migration control register space.
> + * Report only the functional region to Guest.
> + */
> + info.size = pci_resource_len(pdev, info.index) / 2;
> +
> + info.flags = VFIO_REGION_INFO_FLAG_READ |
> + VFIO_REGION_INFO_FLAG_WRITE |
> + VFIO_REGION_INFO_FLAG_MMAP;
> +
> + return copy_to_user((void __user *)arg, &info, minsz) ?
> + -EFAULT : 0;
> + }
> + }
> + return vfio_pci_core_ioctl(core_vdev, cmd, arg);
> +}
> +
> static int hisi_acc_vfio_pci_open_device(struct vfio_device *core_vdev)
> {
> struct vfio_pci_core_device *vdev =
> @@ -28,6 +141,19 @@ static int hisi_acc_vfio_pci_open_device(struct vfio_device *core_vdev)
> return 0;
> }
>
> +static const struct vfio_device_ops hisi_acc_vfio_pci_migrn_ops = {
> + .name = "hisi-acc-vfio-pci-migration",
> + .open_device = hisi_acc_vfio_pci_open_device,
> + .close_device = vfio_pci_core_close_device,
> + .ioctl = hisi_acc_vfio_pci_ioctl,
> + .device_feature = vfio_pci_core_ioctl_feature,
> + .read = hisi_acc_vfio_pci_read,
> + .write = hisi_acc_vfio_pci_write,
> + .mmap = hisi_acc_vfio_pci_mmap,
> + .request = vfio_pci_core_request,
> + .match = vfio_pci_core_match,
> +};
> +
> static const struct vfio_device_ops hisi_acc_vfio_pci_ops = {
> .name = "hisi-acc-vfio-pci",
> .open_device = hisi_acc_vfio_pci_open_device,
>

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