On Thu, Jul 19, 2012 at 01:45:20PM +0300, Michael S. Tsirkin wrote: > When more than 1 source id is in use for the same GSI, we have the > following race related to handling irq_states race: > > CPU 0 clears bit 0. CPU 0 read irq_state as 0. CPU 1 sets level to 1. > CPU 1 calls kvm_ioapic_set_irq(1). CPU 0 calls kvm_ioapic_set_irq(0). > Now ioapic thinks the level is 0 but irq_state is not 0. > > Fix by performing all irq_states bitmap handling under pic/ioapic lock. > This also removes the need for atomics with irq_states handling. > > Reported-by: Gleb Natapov <gleb@xxxxxxxxxx> > Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx> > --- Applied, thanks. > Changes from v1: > Address comments by Gleb and Alex: > renamed some variables for clarify > renamed kvm_irq_line_state -> __kvm_irq_line_state > > Any chance we can put this in 3.5? I know level IRQs are not widely > used, which is likely why this went unnoticed for so long, but still ... http://yarchive.net/comp/linux/merge_window.html "From: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> The thing is, I don't take bug fixes late in the -rc just because they are bug fixes. And I really shouldn't. If it's an old bug, and doesn't cause an oops or a security issue, it had damn well better wait for the next merge window. There is absolutely _no_ reason to just blindly "fix bugs" at the end of the rc stage, because quite frankly, the risks coming from fixing a bug is often bigger than the advantage. " -- 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
