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.

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
>