Am 06.01.2011 20:24, Anthony Liguori wrote:
On 01/06/2011 11:56 AM, Marcelo Tosatti wrote:
From: Jan Kiszka<address@hidden>
QEMU supports only one VM, so there is only one kvm_state per process,
and we gain nothing passing a reference to it around. Eliminate any need
to refer to it outside of kvm-all.c.
Signed-off-by: Jan Kiszka<address@hidden>
CC: Alexander Graf<address@hidden>
Signed-off-by: Marcelo Tosatti<address@hidden>
I think this is a big mistake.
Obviously, I don't share your concerns. :)
Having to manage kvm_state keeps the abstraction lines well defined.
How does it help?
Otherwise, it's far too easy for portions of code to call into KVM
functions that really shouldn't.
I can't imagine we gain anything from requiring kvm_check_extension
callers to hold a kvm_state "capability". Yes, it's now much easier to
call kvm_[vm_]ioctl, but that's the key point of this change:
So far we primarily complicated the internal interface between generic
and arch-dependent kvm parts by requiring kvm_state joggling. But
external users already find interfaces without this restriction
(kvm_log_*, kvm_ioeventfd_*, ...). That's because it's at least
complicated to _cleanly_ pass kvm_state references to all users that
need it - e.g. sysbus devices like kvmclock or upcoming in-kernel irqchips.