On 06.08.2025 10:22, Roger Pau Monné wrote:
> On Tue, Aug 05, 2025 at 10:43:09AM +0200, Jan Beulich wrote:
>> On 05.08.2025 05:49, Jiqian Chen wrote:
>>> --- a/xen/drivers/vpci/msix.c
>>> +++ b/xen/drivers/vpci/msix.c
>>> @@ -655,6 +655,48 @@ int vpci_make_msix_hole(const struct pci_dev *pdev)
>>> return 0;
>>> }
>>>
>>> +static int cf_check cleanup_msix(const struct pci_dev *pdev)
>>> +{
>>> + int rc;
>>> + struct vpci *vpci = pdev->vpci;
>>> + const unsigned int msix_pos = pdev->msix_pos;
>>> +
>>> + if ( !msix_pos )
>>> + return 0;
>>> +
>>> + rc = vpci_remove_registers(vpci, msix_control_reg(msix_pos), 2);
>>> + if ( rc )
>>> + {
>>> + printk(XENLOG_ERR "%pd %pp: fail to remove MSIX handlers rc=%d\n",
>>> + pdev->domain, &pdev->sbdf, rc);
>>> + ASSERT_UNREACHABLE();
>>> + return rc;
>>> + }
>>> +
>>> + if ( vpci->msix )
>>> + {
>>> + list_del(&vpci->msix->next);
>>> + for ( unsigned int i = 0; i < ARRAY_SIZE(vpci->msix->table); i++ )
>>> + if ( vpci->msix->table[i] )
>>> + iounmap(vpci->msix->table[i]);
>>> +
>>> + XFREE(vpci->msix);
>>> + }
>>> +
>>> + /*
>>> + * The driver may not traverse the capability list and think device
>>> + * supports MSIX by default. So here let the control register of MSIX
>>> + * be Read-Only is to ensure MSIX disabled.
>>> + */
>>> + rc = vpci_add_register(vpci, vpci_hw_read16, NULL,
>>> + msix_control_reg(msix_pos), 2, NULL);
>>> + if ( rc )
>>> + printk(XENLOG_ERR "%pd %pp: fail to add MSIX ctrl handler rc=%d\n",
>>> + pdev->domain, &pdev->sbdf, rc);
>>
>> Here as well as for MSI: Wouldn't this better be limited to the init-failure
>> case? No point in adding a register hook (and possibly emitting a misleading
>> log message) when we're tearing down anyway. IOW I think the ->cleanup()
>> hook needs a boolean parameter, unless the distinction of the two cases can
>> be (reliably) inferred from some other property.
>
> I don't think we have any signal in pci_dev itself that notices
> whether the device is being deassigned, in which case it does need an
> extra boolean parameter to notice whether to add the r/o handler.
>
> I'm also wondering whether we want to limit this hiding to the
> hardware domain only, and for domUs fail the operation instead, and
> fail to assign the device. That can be adjusted in a later patch
> though.
Yes, DomU wants handling as you say. Iirc there are other open issues with
DomU support, though. Hence yes, "later" ought to suffice here. Perhaps
worth annotating with a fixme, though, to be able to easily spot all the
places that require adjustment.
Jan
