Am 06.01.2011 20:24, Anthony Liguori wrote: > On 01/06/2011 11:56 AM, Marcelo Tosatti wrote: >> From: Jan Kiszka<jan.kiszka@xxxxxxxxxxx> >> >> 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<jan.kiszka@xxxxxxxxxxx> >> CC: Alexander Graf<agraf@xxxxxxx> >> Signed-off-by: Marcelo Tosatti<mtosatti@xxxxxxxxxx> >> > > 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. Let's just stop this artificial abstraction that has no practical use and focus on detecting layering violations via code review. That's more reliable IMHO. Jan
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