>>> On 24.06.16 at 11:57, <yu.c.zh...@linux.intel.com> wrote: > On 6/24/2016 4:01 PM, Jan Beulich wrote: >>>>> On 24.06.16 at 09:12, <yu.c.zh...@linux.intel.com> wrote: >>> On 6/24/2016 2:12 PM, Jan Beulich wrote: >>>> And then, thinking about it again especially in the context of >>>> the hvmctl series - the unbinding of the type is happening in a >>>> hypercall with built-in preemption capability. Hence there's not >>>> really an issue with how long that conversion may take, as >>>> long as there's no need to pause the guest for that time period. >>>> Which means you could first initiate conversion via the >>>> misconfig mechanism, but then immediately go ahead and walk >>>> the entire guest address space (or the relevant part of it, if >>>> the bounds got tracked) with continuations used as necessary. >>> Sorry, what's the misconfig mechanism good for if I still need to sweep >>> the entire >>> p2m table immediately? >> To avoid the need to pause the guest for an extended time: At >> least between scheduling a continuation and executing it, the >> guest could happily run (and perhaps cause some of the >> otherwise synchronous - to the hypercall - work to get carried >> out already, with the involved execution time accounted to the >> guest instead of the host). > > By "scheduling a continuation and executing it", do you mean code like > hypercall_create_continuation? I'll need to study on this part. But one > difference I can imagine is that the hypercall_create_continuation is of > uncompleted hypercalls I guess, yet the p2m table sweeping may only > be a side effect of the unbound hypercall here.
Side effect or not, it'll take long and hence you can't do it in one go. Hence the need for a continuation. We have at least one other such example - see paging_domctl(). I don't think you'll need an auxiliary new hypercall here, though. Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
