On Tue, Aug 19, 2014 at 10:53:16AM +0200, Eric Auger wrote: > On 08/13/2014 04:55 PM, Christoffer Dall wrote: > > On Mon, Aug 04, 2014 at 02:08:22PM +0200, Eric Auger wrote: > >> This patch enables irqfd on ARM. > >> > >> irqfd framework enables to inject a virtual IRQ into a guest upon an > >> eventfd trigger. User-side uses KVM_IRQFD VM ioctl to provide KVM with > >> a kvm_irqfd struct that associates a VM, an eventfd, an IRQ number > >> (aka. the gsi). When an actor signals the eventfd (typically a VFIO > >> platform driver), the kvm irqfd subsystem injects the provided virtual > >> IRQ into the guest. > >> > >> The gsi must correspond to a shared peripheral interrupt (SPI), ie the > >> GIC interrupt ID is gsi+32. > > > > Why can't we support PPIs? > Hi Christoffer, > > Well, in case we want to support PPI at irqfd level, we would need to > change the semantic of the GSI value and use the same as KVM_IRQ_LINE, > to specify the target vcpu. This is obviously feasible but this also > induces changes in currently generic user parts, vfio, vhost. is PPI > injection though irqfd a valid use case? I don't see why you wouldn't want to be able to support PPIs as passthrough interrupts to a guest? [...] > >> + > >> +/* MSI not implemented yet */ > > > > yet? What is an MSI on ARM? > Well some MSI support comes with GICv2m and GICv3. My current > understanding is it makes sense to inject an MSI from an irqfd trigger. > Don't you share this understanding? > Doh, I read GSI and wrote MSI, of course, complete brain meltdown on my side. -Christoffer -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
