Re: [Xen-devel] PCI Pass-through in Xen ARM - Draft 2.

[Julien Grall <julien.grall@xxxxxxxxxx>]

Hi Manish,

On 28/06/15 19:38, Manish Jaggi wrote:
> 4.1 Holes in guest memory space
> ----------------------------
> Holes are added in the guest memory space for mapping pci device's BAR
> regions.
> These are defined in arch-arm.h
> 
> /* For 32bit */
> GUEST_MMIO_HOLE0_BASE, GUEST_MMIO_HOLE0_SIZE
>  
> /* For 64bit */
> GUEST_MMIO_HOLE1_BASE , GUEST_MMIO_HOLE1_SIZE

The memory layout for 32bit and 64bit are exactly the same. Why do you
need to differ here?

> 4.2 New entries in xenstore for device BARs
> --------------------------------------------
> toolkit also updates the xenstore information for the device
> (virtualbar:physical bar).
> This information is read by xenpciback and returned to the pcifront
> driver configuration
> space accesses.

Can you details what do you plan to put in xenstore and how?

What about the expansion ROM?

> 4.3 Hypercall for bdf mapping notification to xen
> -----------------------------------------------
> #define PHYSDEVOP_map_sbdf              43
> typedef struct {
>     u32 s;
>     u8 b;
>     u8 df;
>     u16 res;
> } sbdf_t;
> struct physdev_map_sbdf {
>     int domain_id;
>     sbdf_t    sbdf;
>     sbdf_t    gsbdf;
> };
> 
> Each domain has a pdev list, which contains the list of all pci devices.
> The
> pdev structure already has a sbdf information. The arch_pci_dev is
> updated to
> contain the gsbdf information. (gs- guest segment id)
> 
> Whenever there is trap from guest or an interrupt has to be injected,
> the pdev
> list is iterated to find the gsbdf.

Can you give more background for this section? i.e:
        - Why do you need this?
        - How xen will translate the gbdf to a vDeviceID?
        - Who will call this hypercall?
        - Why not setting the gsbdf when the device is assigned?

Regards,

-- 
Julien Grall

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