On 30 November 2014 at 10:10, Christoffer Dall <christoffer.dall@xxxxxxxxxx> wrote: > In any case, I think it was related to how userspace observes the state > of the CPU, because when you do the MMIO operation emulation in > userspace, currently if you observe the PC though GET_ONE_REG, you'll > see a PC pointing to the next instruction, not the one you're emulating > which is strange. Also if we ever add support for userspace to say "this MMIO should fault" then we definitely need the PC-advance to happen afterwards, not before. > Not sure what the relation to a guest single-stepping itself was. I think it just came up in the course of that discussion, because single-step handling also needs to perform an action (clear PSTATE.SS) as part of the "advance over this insn" operation. But I think that you're right that doing the advance before dropping out to userspace is no worse for singlestep than it is for any other case. -- PMM -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
