[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [RFC KERNEL PATCH v2 2/3] xen/pvh: Unmask irq for passthrough device in PVH dom0
On 2023/12/12 19:39, Roger Pau Monné wrote: > On Tue, Dec 12, 2023 at 12:19:49PM +0100, Jan Beulich wrote: >> On 12.12.2023 12:18, Roger Pau Monné wrote: >>> On Tue, Dec 12, 2023 at 10:38:08AM +0100, Jan Beulich wrote: >>>> (I think the Cc list is too long here, but then I don't know who to >>>> keep and who to possibly drop.) >>>> >>>> On 12.12.2023 09:49, Roger Pau Monné wrote: >>>>> On Tue, Dec 12, 2023 at 06:16:43AM +0000, Chen, Jiqian wrote: >>>>>> On 2023/12/11 23:45, Roger Pau Monné wrote: >>>>>>> On Wed, Dec 06, 2023 at 06:07:26AM +0000, Chen, Jiqian wrote: >>>>>>>> +static int xen_pvh_setup_gsi(gsi_info_t *gsi_info) >>>>>>>> +{ >>>>>>>> + struct physdev_setup_gsi setup_gsi; >>>>>>>> + >>>>>>>> + setup_gsi.gsi = gsi_info->gsi; >>>>>>>> + setup_gsi.triggering = (gsi_info->trigger == >>>>>>>> ACPI_EDGE_SENSITIVE ? 0 : 1); >>>>>>>> + setup_gsi.polarity = (gsi_info->polarity == ACPI_ACTIVE_HIGH ? >>>>>>>> 0 : 1); >>>>>>>> + >>>>>>>> + return HYPERVISOR_physdev_op(PHYSDEVOP_setup_gsi, &setup_gsi); >>>>>>>> +} >>>>>>> >>>>>>> Hm, why not simply call pcibios_enable_device() from pciback? What >>>>>> pcibios_enable_device had been called when using cmd "xl >>>>>> pci-assignable-add sbdf" from pciback. But it didn't do map_pirq and >>>>>> setup_gsi. >>>>>> Because pcibios_enable_device-> pcibios_enable_irq-> >>>>>> __acpi_register_gsi(acpi_register_gsi_ioapic PVH specific) >>>>>>> you are doing here using the hypercalls is a backdoor into what's done >>>>>>> automatically by Xen on IO-APIC accesses by a PVH dom0. >>>>>> But the gsi didn't be unmasked, and vioapic_hwdom_map_gsi is never >>>>>> called. >>>>>> So, I think in pciback, if we can do what vioapic_hwdom_map_gsi does. >>>>>> >>>>> >>>>> I see, it does setup the IO-APIC pin but doesn't unmask it, that's >>>>> what I feared. >>>>> >>>>>>> It will be much more natural for the PVH dom0 model to simply use the >>>>>>> native way to configure and unmask the IO-APIC pin, and that would >>>>>>> correctly setup the triggering/polarity and bind it to dom0 without >>>>>>> requiring the usage of any hypercalls. >>>>>> Do you still prefer that I called unmask_irq in pcistub_init_device, as >>>>>> this v2 patch do? >>>>>> But Thomas Gleixner think it is not suitable to export unmask_irq. >>>>> >>>>> Yeah, that wasn't good. >>>>> >>>>>>> >>>>>>> Is that an issue since in that case the gsi will get mapped and bound >>>>>>> to dom0? >>>>>> Dom0 do map_pirq is to pass the check xc_domain_irq_permission()-> >>>>>> pirq_access_permitted(), >>>>> >>>>> Can we see about finding another way to fix this check? >>>>> >>>>> One option would be granting permissions over the IRQ in >>>>> PHYSDEVOP_setup_gsi? >>>> >>>> There's no domain available there, and imo it's also the wrong interface to >>>> possibly grant any permissions. >>> >>> Well, the domain is the caller. >> >> Granting permission to itself? > > See below in the previous email, the issue is not with the > permissions, which are correctly assigned from > dom0_setup_permissions(), but the usage of domain_pirq_to_irq() in > pirq_access_permitted() as called by XEN_DOMCTL_irq_permission. > There's no need to play with the permissions at all. Yes, the problem is pci_add_dm_done-> xc_domain_irq_permission-> XEN_DOMCTL_irq_permission-> pirq_access_permitted->domain_pirq_to_irq->return irq is 0, so it failed. I am think that since the PVH doesn't use pirq, can we just skip this irq_permission check for PVH? > > Regards, Roger. -- Best regards, Jiqian Chen.
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