Messages in this thread | | | Date | Fri, 19 Feb 2021 18:10:56 +0000 | From | Marc Zyngier <> | Subject | Re: [PATCH 0/8] arm64: Support FIQ controller registration |
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Hi Mark,
On Fri, 19 Feb 2021 11:38:56 +0000, Mark Rutland <mark.rutland@arm.com> wrote: > > Hector's M1 support series [1] shows that some platforms have critical > interrupts wired to FIQ, and to support these platforms we need to support > handling FIQ exceptions. Other contemporary platforms don't use FIQ (since e.g. > this is usually routed to EL3), and as we never expect to take an FIQ, we have > the FIQ vector cause a panic. > > Since the use of FIQ is a platform integration detail (which can differ across > bare-metal and virtualized environments), we need be able to explicitly opt-in > to handling FIQs while retaining the existing behaviour otherwise. This series > adds a new set_handle_fiq() hook so that the FIQ controller can do so, and > where no controller is registered the default handler will panic(). For > consistency the set_handle_irq() code is made to do the same. > > The first couple of patches are from Marc's irq/drop-generic_irq_multi_handler > branch [2] on kernel.org, and clean up CONFIG_GENERIC_IRQ_MULTI_HANDLER usage. > The next four patches move arm64 over to a local set_handle_irq() > implementation, which is written to share code with a set_handle_fiq() function > in the last two patches. The only functional difference here is that if an IRQ > is somehow taken prior to set_handle_irq() the default handler will directly > panic() rather than the vector branching to NULL. > > The penultimate patch is cherry-picked from the v2 M1 series, and as per > discussion there [3] will need a few additional fixups. I've included it for > now as the DAIF.IF alignment is necessary for the FIQ exception handling added > in the final patch. > > The final patch adds the low-level FIQ exception handling and registration > mechanism atop the prior rework.
Thanks for putting this together. I have an extra patch on top of this series[1] that prevents the kernel from catching fire if a FIQ fires whilst running a guest. Nothing urgent, we can queue it at a later time.
Thanks,
M.
[1] https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/log/?h=irq/fiq
-- Without deviation from the norm, progress is not possible.
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