On 2012-02-11 14:54, Blue Swirl wrote: > On Sat, Feb 11, 2012 at 12:43, Jan Kiszka <jan.kiszka@xxxxxx> wrote: >> On 2012-02-11 12:49, Andreas Färber wrote: >>> Am 11.02.2012 12:25, schrieb Blue Swirl: >>>> I think using cpu_single_env is an indication of a problem, like poor >>>> code, layering violation or poor API (vmport). What is your use case? >>> >>> I couldn't spot any in this series. Jan, note that any new use of env or >>> cpu_single_env will need to be redone when we convert to QOM CPU. >> >> cpu_single_env should have nothing to do with QOM. >> >> The ABIs of vmport and the KVM VAPI require a reference to the calling >> VCPU, and that's why you find tons of them in patch 5. > > Yes, this seems to be another case of a badly designed ABI. I guess > there is no way to change that anymore, just like vmport? Believe me, I grumbled over it more than once while porting it from qemu-kvm. The point is that some (Windows) VMs out there are running already with this option ROM loaded and working this unfortunate ABI. > > Some of the cpu_single_env accesses in patch 5 could be avoided when > APIC is moved closer to CPU. VAPIC should be also close to APIC so it > should be able to access the CPU directly. In some other cases the > current state could be passed around instead once it is known. Some callbacks are I/O-port originated, ie. not associated with the per-CPU MMIO area or some MSR. So we would have to pass down the causing CPU to every I/O handler - not sure if that is desired... Jan
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