Hi Andre, On Mon, Oct 31 2016 at 05:21:37 PM, Andre Przywara <andre.przywara@xxxxxxx> wrote: > In our VGIC implementation we limit the number of SPIs to a number > that the userland application told us. Accordingly we limit the > allocation of memory for virtual IRQs to that number. > However in our MMIO dispatcher we didn't check if we ever access an > IRQ beyond that limit, leading to out-of-bound accesses. > Add a test against the number of allocated SPIs in check_region(). > Adjust the VGIC_ADDR_TO_INTID macro to avoid an actual division, which > is not implemented on ARM(32). > > [maz: cleaned-up original patch] > > Cc: stable@xxxxxxxxxxxxxxx > Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx> > Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx> > --- > Hi Marc, > > does the last hunk fix the GCC issue that your recent fix addresses > as well? ilog2 seems to be pretty cheap on ARM and ARM64, so I wonder > if this version of the fix is better, since smaller? Thanks for looking into this. That seems to solve it for me (with GCC 6.1.1). [...] > diff --git a/virt/kvm/arm/vgic/vgic-mmio.h b/virt/kvm/arm/vgic/vgic-mmio.h > index 4c34d39..dacd1155 100644 > --- a/virt/kvm/arm/vgic/vgic-mmio.h > +++ b/virt/kvm/arm/vgic/vgic-mmio.h > @@ -58,7 +58,7 @@ extern struct kvm_io_device_ops kvm_io_gic_ops; > * numerator and denominator with 8 to support at most 64 bits per IRQ: > */ > #define VGIC_ADDR_TO_INTID(addr, bits) (((addr) & VGIC_ADDR_IRQ_MASK(bits)) * \ > - 64 / (bits) / 8) > + 64 >> (ilog2(bits) + 3)) Given that it's taken me the best of 10 minutes to convince myself that this was correct, can you please save everybody some time by updating the comment above the #define? Please respin this as soon as you can. Thanks, M. -- Jazz is not dead. It just smells funny. -- 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
