Re: [PATCH v5] vfio/pci: Add support for opregion v2.1+

[Zhenyu Wang <zhenyuw@linux.intel.com>]

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On 2021.03.26 01:09:53 +0800, Fred Gao wrote:
> Before opregion version 2.0 VBT data is stored in opregion mailbox #4,
> but when VBT data exceeds 6KB size and cannot be within mailbox #4
> then from opregion v2.0+, Extended VBT region, next to opregion is
> used to hold the VBT data, so the total size will be opregion size plus
> extended VBT region size.
> 
> Since opregion v2.0 with physical host VBT address would not be
> practically available for end user and guest can not directly access
> host physical address, so it is not supported.
> 
> Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
> Signed-off-by: Swee Yee Fonn <swee.yee.fonn@intel.com>
> Signed-off-by: Fred Gao <fred.gao@intel.com>
> ---

Reviewed-by: Zhenyu Wang <zhenyuw@linux.intel.com>

Hi, Alex, pls let us know if you have other concern to merge this one.

Thanks!

>  drivers/vfio/pci/vfio_pci_igd.c | 53 +++++++++++++++++++++++++++++++++
>  1 file changed, 53 insertions(+)
> 
> diff --git a/drivers/vfio/pci/vfio_pci_igd.c b/drivers/vfio/pci/vfio_pci_igd.c
> index e66dfb0178ed..228df565e9bc 100644
> --- a/drivers/vfio/pci/vfio_pci_igd.c
> +++ b/drivers/vfio/pci/vfio_pci_igd.c
> @@ -21,6 +21,10 @@
>  #define OPREGION_SIZE		(8 * 1024)
>  #define OPREGION_PCI_ADDR	0xfc
>  
> +#define OPREGION_RVDA		0x3ba
> +#define OPREGION_RVDS		0x3c2
> +#define OPREGION_VERSION	0x16
> +
>  static size_t vfio_pci_igd_rw(struct vfio_pci_device *vdev, char __user *buf,
>  			      size_t count, loff_t *ppos, bool iswrite)
>  {
> @@ -58,6 +62,7 @@ static int vfio_pci_igd_opregion_init(struct vfio_pci_device *vdev)
>  	u32 addr, size;
>  	void *base;
>  	int ret;
> +	u16 version;
>  
>  	ret = pci_read_config_dword(vdev->pdev, OPREGION_PCI_ADDR, &addr);
>  	if (ret)
> @@ -83,6 +88,54 @@ static int vfio_pci_igd_opregion_init(struct vfio_pci_device *vdev)
>  
>  	size *= 1024; /* In KB */
>  
> +	/*
> +	 * 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 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.
> +	 */
> +	version = le16_to_cpu(*(__le16 *)(base + OPREGION_VERSION));
> +	if (version >= 0x0200) {
> +		u64 rvda;
> +		u32 rvds;
> +
> +		rvda = le64_to_cpu(*(__le64 *)(base + OPREGION_RVDA));
> +		rvds = le32_to_cpu(*(__le32 *)(base + OPREGION_RVDS));
> +		if (rvda && rvds) {
> +			/* no support for opregion v2.0 with physical VBT address */
> +			if (version == 0x0200) {
> +				memunmap(base);
> +				pci_err(vdev->pdev,
> +					"IGD assignment does not support opregion v2.0 with an extended VBT region\n");
> +				return -EINVAL;
> +			}
> +
> +			if (rvda != size) {
> +				memunmap(base);
> +				pci_err(vdev->pdev,
> +					"Extended VBT does not follow opregion on version 0x%04x\n",
> +					version);
> +				return -EINVAL;
> +			}
> +
> +			/* region size for opregion v2.0+: opregion and VBT size. */
> +			size += rvds;
> +		}
> +	}
> +
>  	if (size != OPREGION_SIZE) {
>  		memunmap(base);
>  		base = memremap(addr, size, MEMREMAP_WB);
> -- 
> 2.24.1.1.gb6d4d82bd5
> 

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