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From: Sunil Muthuswamy <firstname.lastname@example.org> To: Marc Zyngier <email@example.com> Cc: Robin Murphy <firstname.lastname@example.org>, Thomas Gleixner <email@example.com>, "firstname.lastname@example.org" <email@example.com>, "firstname.lastname@example.org" <email@example.com>, "firstname.lastname@example.org" <email@example.com>, "firstname.lastname@example.org" <email@example.com>, Michael Kelley <firstname.lastname@example.org>, Boqun Feng <Boqun.Feng@microsoft.com>, KY Srinivasan <email@example.com>, Arnd Bergmann <firstname.lastname@example.org>, Lorenzo Pieralisi <email@example.com> Subject: RE: [EXTERNAL] Re: [RFC 1/1] irqchip/gic-v3-its: Add irq domain and chip for Direct LPI without ITS Date: Tue, 10 Aug 2021 01:10:40 +0000 [thread overview] Message-ID: <MW4PR21MB20022D4903CDD8F989C30C50C0F79@MW4PR21MB2002.namprd21.prod.outlook.com> (raw) In-Reply-To: <firstname.lastname@example.org> On Monday, August 9, 2021 2:15 AM, Marc Zyngier <email@example.com> wrote: [...] > If you plug directly into the GICv3 layer, I'd rather you inject SPIs, > just like any other non-architectural MSI controller. You can directly > interface with the ACPI GSI layer for that, without any need to mess > with the GICv3 internals. The SPI space isn't very large, but still > much larger than the equivalent x86 space (close to 1000). > > If time is of the essence, I suggest you go the SPI way. For anything > involving LPIs, I really want to see a firmware spec that works for > everyone as opposed to a localised Hyper-V hack. > Ok, thanks. Before we commit to anything, I would like to make sure that I am on the same page in terms of your description. With that in mind, I have few questions. Hopefully, these should settle the matter. 1. If we go with the SPI route, then the way I envision it is that the Hyper-V vPCI driver will implement an IRQ chip, which will take care of allocating & managing the SPI interrupt for Hyper-V vPCI. This IRQ chip will parent itself to the architectural GIC IRQ chip for general interrupt management. Does that match with your understanding/suggestion as well? 2. In the above, how will Hyper-V vPCI module discover the architectural GIC IRQ domain generically for virtual devices that are not firmware enumerated? Today, the GIC v3 IRQ domain is not exported and the general 'irq_find_xyz' APIs only work for firmware enumerated devices (i.e. something that has a fwnode handle). 3. Longer term, if we implement LPIs (with an ITS or Direct LPI), to be able to support all scenarios such as Live Migration, the Hyper-V virtual PCI driver would like to be able to control the MSI address & data that gets programmed on the device (i.e. .irq_compose_msi_msg). We can use the architectural methods for everything else. Does that fit into the realm of what would be acceptable upstream? Thanks, Sunil
next prev parent reply other threads:[~2021-08-10 1:10 UTC|newest] Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-07-08 19:36 [RFC 1/1] irqchip/gic-v3-its: Add irq domain and chip for Direct LPI without ITS Sunil Muthuswamy 2021-07-11 11:09 ` Marc Zyngier 2021-07-26 15:33 ` [EXTERNAL] " Sunil Muthuswamy 2021-07-31 9:52 ` Marc Zyngier 2021-08-03 2:11 ` Sunil Muthuswamy 2021-08-03 8:35 ` Robin Murphy 2021-08-04 9:21 ` Marc Zyngier 2021-08-04 20:10 ` Sunil Muthuswamy 2021-08-05 8:35 ` Marc Zyngier 2021-08-06 19:14 ` Sunil Muthuswamy 2021-08-08 10:19 ` Marc Zyngier 2021-08-09 2:35 ` Sunil Muthuswamy 2021-08-09 9:15 ` Marc Zyngier 2021-08-10 1:10 ` Sunil Muthuswamy [this message] 2021-08-10 13:57 ` Marc Zyngier
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