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Re: [Xen-devel] [PATCH v3 20/24] xen/passthrough: Extend XEN_DOMCTL_assign_device to support DT device



Hi Ian,

On 11/03/2015 12:37, Ian Campbell wrote:
On Tue, 2015-03-10 at 16:33 +0000, Julien Grall wrote:
Hi Ian,

On 20/02/15 17:17, Ian Campbell wrote:
+    /* TODO: Do we need to check is_dying? Mostly to protect against
+     * hypercall trying to passthrough a device while we are
+     * dying.

FWIW the PCI case appears not to care...

There is one place in XEN_DOMCTL_assign_device...

Although I don't understand much the usage of is_dying.

+     */
+
+    switch ( domctl->cmd )
+    {
+    case XEN_DOMCTL_assign_device:
+        ret = -ENOSYS;
+        if ( domctl->u.assign_device.dev != XEN_DOMCTL_DEV_DT )
+            break;

You added something similar to iommu_do_pci_domctl, would it not be
preferable for the caller to switch on domctl->u.assign_device.dev and
call the correct iommu_do_*_domctl?

I though about it. It would require to stub iommu_do_*_domctl. So I
preferred to chose the current solution.

You mean iommu_do_{pci,dt}_domctl?

IIRC you already added suitable #defines for when these features are
present, so reusing them at the call sites wouldn't be too bad, or else
stubs aren't the worst thing either.

Hmmm I think I got you point now. Do you mean have something like:

switch (domctl->u.assign_device.dev)
{
#ifdef HAS_PCI
case XEN_DOMCTL_DEV_PCI:
    ret = iommu_do_pci_domctl();
    break;
#endif
#ifdef HAS_DEVICE_TREE
case XEN_DOMCTL_DEV_DT:
    ret = iommu_do_dt_domctl()
    break;
#endif

default:
   ret = -ENOSYS;
}

Regards,

--
Julien Grall

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