On 10/24/2012 08:36 AM, liu ping fan wrote: > On Tue, Oct 23, 2012 at 5:37 PM, Avi Kivity <a...@redhat.com> wrote: >> On 10/23/2012 11:32 AM, liu ping fan wrote: >>> On Tue, Oct 23, 2012 at 5:07 PM, Jan Kiszka <jan.kis...@siemens.com> wrote: >>>> On 2012-10-23 07:52, liu ping fan wrote: >>>>> On Mon, Oct 22, 2012 at 6:40 PM, Avi Kivity <a...@redhat.com> wrote: >>>>>> On 10/22/2012 11:23 AM, Liu Ping Fan wrote: >>>>>>> The broken device state is caused by releasing local lock before >>>>>>> acquiring >>>>>>> big lock. To fix this issue, we have two choice: >>>>>>> 1.use busy flag to protect the state >>>>>>> The drawback is that we will introduce independent busy flag for >>>>>>> each >>>>>>> independent device's logic unit. >>>>>>> 2.reload the device's state >>>>>>> The drawback is if the call chain is too deep, the action to reload >>>>>>> will >>>>>>> touch each layer. Also the reloading means to recaculate the >>>>>>> intermediate >>>>>>> result based on device's regs. >>>>>>> >>>>>>> This patch adopt the solution 1 to fix the issue. >>>>>> >>>>>> Doesn't the nested mmio patch detect this? >>>>>> >>>>> It will only record and fix the issue on one thread. But guest can >>>>> touch the emulated device on muti-threads. >>>> >>>> Sorry, what does that mean? A second VCPU accessing the device will >>>> simply be ignored when it races with another VCPU? Specifically >>>> >>> Yes, just ignored. For device which support many logic in parallel, >>> it should use independent busy flag for each logic >> >> We don't actually know that e1000 doesn't. Why won't writing into >> different registers in parallel work? >> > I think e1000 has only one transfer logic, so one busy flag is enough. > And the normal guest's driver will access the registers one by one. > But anyway, it may have parallel modules. So what about model it like > this > if busy: > wait > > clear busy: > wakeup >
You mean lock()/unlock()? Again I suggest to ignore this issue for now. We need to make progress and we can't get everything perfect (or even agree on everything). When we have converted a few devices, we will have more information and can think of a good solution. -- error compiling committee.c: too many arguments to function
