Messages in this thread | | | Subject | Re: [PART1 RFC v3 12/12] svm: Manage vcpu load/unload when enable AVIC | From | Suravee Suthikulpanit <> | Date | Thu, 31 Mar 2016 15:52:38 +0700 |
| |
Hi Radim,
On 03/19/2016 04:44 AM, Radim Krčmář wrote: > 2016-03-18 01:09-0500, Suravee Suthikulpanit: >> From: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> >> + >> + WRITE_ONCE(*entry, new_entry); > > This will translate to two writes in 32 bit mode and we need to write > physical ID first to avoid spurious doorbells ... > is the order guaranteed?
Hm.. not sure on that.
>> + } else { >> + new_entry = READ_ONCE(*entry); >> + /** >> + * This handles the case when vcpu is scheduled out >> + * and has not yet not called blocking. We save the >> + * AVIC running flag so that we can restore later. >> + */ > > is_running must be disabled in between ...blocking and ...unblocking, > because we don't want to miss interrupts and block forever. > I somehow don't get it from the comment. :)
Not sure if I understand your concern. However, the is_running bit setting/clearing should be handled in the avic_set_running below. This part only handles othe case when the is_running bit still set when calling vcpu_put (and later on loading some other vcpus). This way, when we are re-loading this vcpu, we can restore the is_running bit accordingly.
Thanks, Suravee
| |