[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v2 COLOPre 03/13] libxc/restore: zero ioreq page only one time
On 06/08/2015 06:15 PM, Andrew Cooper wrote: On 08/06/15 10:58, Yang Hongyang wrote:On 06/08/2015 05:46 PM, Andrew Cooper wrote:On 08/06/15 04:43, Yang Hongyang wrote:ioreq page contains evtchn which will be set when we resume the secondary vm the first time. The hypervisor will check if the evtchn is corrupted, so we cannot zero the ioreq page more than one time. The ioreq->state is always STATE_IOREQ_NONE after the vm is suspended, so it is OK if we only zero it one time. Signed-off-by: Yang Hongyang <yanghy@xxxxxxxxxxxxxx> Signed-off-by: Wen congyang <wency@xxxxxxxxxxxxxx> CC: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>The issue here is that we are running the restore algorithm over a domain which has already been running in Xen for a while. This is a brand new usecase, as far as I am aware.Exactly.Does the qemu process associated with this domain get frozen while the secondary is being reset, or does the process get destroyed and recreated.What do you mean by reset? do you mean secondary is suspended at checkpoint?Well - at the point that the buffered records are being processed, we are in the process of resetting the state of the secondary to match the primary. Yes, at this point, the qemu process associated with this domain is frozen. the suspend callback will call libxl__qmp_stop(vm_stop() in qemu) to pause qemu. After we processed all records, qemu will be restored with the received state, that's why we add a libxl__qmp_restore(qemu_load_vmstate() in qemu) api to restore qemu with received state. Currently in libxl, qemu only start with the received state, there's no api to load received state while qemu is running for a while. ~AndrewI have a gut feeling that it would be safer to clear all of the page other than the event channel, but that depends on exactly what else is going on. We absolutely don't want to do is have an update to this page from the primary with an in-progress IOREQ. ~Andrew--- tools/libxc/xc_sr_restore_x86_hvm.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/tools/libxc/xc_sr_restore_x86_hvm.c b/tools/libxc/xc_sr_restore_x86_hvm.c index 6f5af0e..06177e0 100644 --- a/tools/libxc/xc_sr_restore_x86_hvm.c +++ b/tools/libxc/xc_sr_restore_x86_hvm.c @@ -78,7 +78,8 @@ static int handle_hvm_params(struct xc_sr_context *ctx, break; case HVM_PARAM_IOREQ_PFN: case HVM_PARAM_BUFIOREQ_PFN: - xc_clear_domain_page(xch, ctx->domid, entry->value); + if ( !ctx->restore.buffer_all_records ) + xc_clear_domain_page(xch, ctx->domid, entry->value); break; }.. -- Thanks, Yang. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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