Hi Florian, On Tue, 19 May 2020 10:50:46 -0700 Florian Fainelli <[email protected]> wrote:
> On 5/19/2020 9:17 AM, Marc Zyngier wrote: > > For as long as SMP ARM has existed, IPIs have been handled as > > something special. The arch code and the interrupt controller exchange > > a couple of hooks (one to generate an IPI, another to handle it). > > > > Although this is perfectly manageable, it prevents the use of features > > that we could use if IPIs were Linux IRQs (such as pseudo-NMIs). It > > also means that each interrupt controller driver has to follow an > > architecture-specific interface instead of just implementing the base > > irqchip functionnalities. The arch code also duplicates a number of > > things that the core irq code already does (such as calling > > set_irq_regs(), irq_enter()...). > > > > This series tries to remedy this on arm/arm64 by offering a new > > registration interface where the irqchip gives the arch code a range > > of interrupts to use for IPIs. The arch code requests these as normal > > interrupts. > > > > The bulk of the work is at the interrupt controller level, where all 3 > > irqchips used on arm64 get converted. > > > > Finally, the arm64 code drops the legacy registration interface. The > > same thing could be done on 32bit as well once the two remaining > > irqchips using that interface get converted. > > > > There is probably more that could be done: statistics are still > > architecture-private code, for example, and no attempt is made to > > solve that (apart from hidding the IRQs from /proc/interrupt). > > > > This has been tested on a bunch of 32 and 64bit guests. > > Does this patch series change your position on this patch series > > https://lore.kernel.org/linux-arm-kernel/[email protected]/T/ > > or is this still a no-no? I don't think this series changes anything. There is no easy way to reserve SGIs in a way that would work for all combination of OS and FW, and the prospect of sending SGIs between S and NS has already been dubious (yes, the GIC architecture allows it, but it has been written by people who have never designed any large piece of SW). Thanks, M. -- Jazz is not dead. It just smells funny...
