On Sun, 3 Oct 2021 23:53:10 +0800
Colin Xu <colin.xu@xxxxxxxxx> wrote:
...
> static ssize_t vfio_pci_igd_rw(struct vfio_pci_core_device *vdev,
> char __user *buf, size_t count, loff_t *ppos,
> bool iswrite)
> {
> unsigned int i = VFIO_PCI_OFFSET_TO_INDEX(*ppos) - VFIO_PCI_NUM_REGIONS;
> - void *base = vdev->region[i].data;
> - loff_t pos = *ppos & VFIO_PCI_OFFSET_MASK;
> + struct igd_opregion_vbt *opregionvbt = vdev->region[i].data;
> + loff_t pos = *ppos & VFIO_PCI_OFFSET_MASK, off = 0;
> + size_t remaining;
>
> if (pos >= vdev->region[i].size || iswrite)
> return -EINVAL;
>
> count = min(count, (size_t)(vdev->region[i].size - pos));
> + remaining = count;
> +
> + /* Copy until OpRegion version */
> + if (remaining && pos < OPREGION_VERSION) {
> + size_t bytes = min(remaining, OPREGION_VERSION - (size_t)pos);
mint_t(size_t,...) is probably the better option than casting the
individual operands, especially when we're casting multiple operands as
below.
> +
> + if (igd_opregion_shift_copy(buf, &off,
> + opregionvbt->opregion + pos, &pos,
> + &remaining, bytes))
> + return -EFAULT;
> + }
>
...
> /*
> - * Support opregion v2.1+
> - * When VBT data exceeds 6KB size and cannot be within mailbox #4, then
> - * the Extended VBT region next to opregion is used to hold the VBT data.
> - * RVDA (Relative Address of VBT Data from Opregion Base) and RVDS
> - * (Raw VBT Data Size) from opregion structure member are used to hold the
> - * address from region base and size of VBT data. RVDA/RVDS are not
> - * defined before opregion 2.0.
> + * OpRegion and VBT:
> + * When VBT data doesn't exceed 6KB, it's stored in Mailbox #4.
> + * When VBT data exceeds 6KB size, Mailbox #4 is no longer large enough
> + * to hold the VBT data, the Extended VBT region is introduced since
> + * OpRegion 2.0 to hold the VBT data. Since OpRegion 2.0, RVDA/RVDS are
> + * introduced to define the extended VBT data location and size.
> + * OpRegion 2.0: RVDA defines the absolute physical address of the
> + * extended VBT data, RVDS defines the VBT data size.
> + * OpRegion 2.1 and above: RVDA defines the relative address of the
> + * extended VBT data to OpRegion base, RVDS defines the VBT data size.
> *
> - * opregion 2.1+: RVDA is unsigned, relative offset from
> - * opregion base, and should point to the end of opregion.
> - * otherwise, exposing to userspace to allow read access to everything between
> - * the OpRegion and VBT is not safe.
> - * RVDS is defined as size in bytes.
> - *
> - * opregion 2.0: rvda is the physical VBT address.
> - * Since rvda is HPA it cannot be directly used in guest.
> - * And it should not be practically available for end user,so it is not supported.
> + * Due to the RVDA difference in OpRegion VBT (also the only diff between
> + * 2.0 and 2.1), expose OpRegion and VBT as a contiguous range for
> + * OpRegion 2.0 and above makes it possible to support the non-contiguous
The lines ending between$ and contiguous$ are still just over 80
columns. Thanks,
Alex
