RE: [EXTERNAL] pcib msix allocation in arm64

> -----Original Message-----
> From: Andrew Turner <andrew@fubar.geek.nz>
> Sent: Thursday, November 3, 2022 6:21 PM
> To: Souradeep Chakrabarti <schakrabarti@microsoft.com>
> Cc: Warner Losh <imp@bsdimp.com>; Wei Hu <weh@microsoft.com>; freebsd-
> hackers@FreeBSD.org
> Subject: Re: [EXTERNAL] pcib msix allocation in arm64
> 
> Hi Souradeep,
> 
> For the vmbus_pcib driver you’ll need to implement the pcib_alloc_msi,
> pcib_release_msi, and the msix versions, and pcib_map_msi.
> 
> For alloc and release you can just call into the same intr_* function as
> pci_host_generic_acpi.c. You’ll need to pass in the xref for the interrupt
> controller. It needs to be the xref the MSI controller registered. For the GICv2m
> it’s ACPI_MSI_XREF.
> 
[Souradeep] 
I have used following in vmbus_pcib.c :
ret = intr_alloc_msix(pcib, dev, ACPI_MSI_XREF, irq);
But it is failing in pic_lookup() with ESRCH by not finding pic with ACPI_MSI_XREF.
Do I need to do anything for pic_lookup() to be successful?

> For pcib_map_msi I am unsure if the current code is valid on arm64. If not you’ll
> need to call intr_map_msi.
> 
> Andrew
> 
> > On 2 Nov 2022, at 22:27, Souradeep Chakrabarti <schakrabarti@microsoft.com>
> wrote:
> >
> > Hi Andrew,
> > Thanks for the reply. Regarding generic_pcie_acpi_alloc_msix( ), it
> > can be called if the PCI device is child of the generic pcib (
> DRIVER_MODULE(pcib, acpi, generic_pcie_acpi_driver, 0, 0) .
> > But if the PCI device is communicating with a different pcib driver
> > (like vmbus_pcib), in that case do we need to implement all these functions of
> pci_host_generic_acpi.c ?
> >
> > Or there are some ways to reuse them?
> >
> >> -----Original Message-----
> >> From: Andrew Turner <andrew@fubar.geek.nz>
> >> Sent: Wednesday, November 2, 2022 6:54 PM
> >> To: Souradeep Chakrabarti <schakrabarti@microsoft.com>
> >> Cc: Warner Losh <imp@bsdimp.com>; Wei Hu <weh@microsoft.com>;
> >> freebsd- hackers@FreeBSD.org
> >> Subject: [EXTERNAL] Re: pcib msix allocation in arm64
> >>
> >>
> >>> On 2 Nov 2022, at 12:56, Souradeep Chakrabarti
> >>> <schakrabarti@microsoft.com>
> >> wrote:
> >>>
> >>> Hi,
> >>> I can see in x86 nexus.c has implemented pcib_alloc_msix using
> >> nexus_alloc_msix().
> >>> Which calls msix_alloc() for msix allocation.
> >>>
> >>> But in case of arm64 I don't find similar pcib_alloc_msix
> >>> implementation in
> >> nexus.c .
> >>> So, on arm64 what is correct way to get allocate msix ?
> >>
> >> For an arm64 system with ACPI it is most likely handled in
> >> generic_pcie_acpi_release_msix. For FDT it can depend on which PCI
> >> driver is used.
> >>
> >> In either case it will call into intr_release_msix that then calls
> >> into the MSI controller to allocate the vectors. For a GICv3 driver
> >> it will either be gicv3_its_alloc_msix if you have an ITS device, or
> >> gic_v3_alloc_msix if using MBI ranges.
> >>
> >> On ACPI we don’t currently support MBI ranges, although it looks like
> >> this could be handled by the existing gicv2m driver. This driver
> >> should already work as a child of the GICv3, however it appears to be
> >> FDT only, so will need some work to add ACPI support.
> >>
> >> Andrew
> >