2016-03-31 15:52+0700, Suravee Suthikulpanit:
On 03/19/2016 04:44 AM, Radim KrÄmÃÅ wrote:
2016-03-18 01:09-0500, Suravee Suthikulpanit:
+ } 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.
I think that the comment is misleading. The saved is_running flag only
matters after svm_vcpu_blocking, yet the comment says that it handles
the irrelevant case before.
Another minor bug is that was_running isn't initialized to 1, so we need
to halt before is_running gets set.
It would be clearer to toggle a flag in svm_vcpu_(un)blocking and set
is_running = !is_blocking.
Doing so will also be immeasurably faster,
because avic_vcpu_load is called far more than svm_vcpu_(un)blocking.