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Re: [Qemu-devel] [PATCH v2 5/6] kvm: add PV MMIO
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [PATCH v2 5/6] kvm: add PV MMIO |
Date: |
Thu, 4 Apr 2013 17:38:20 +0300 |
On Thu, Apr 04, 2013 at 04:56:11PM +0200, Paolo Bonzini wrote:
> Il 04/04/2013 15:10, Michael S. Tsirkin ha scritto:
> > > I would like Avi to comment on this, because I think this is not the
> > > "memory-API approved" way of doing things. You need KVM to define its
> > > own AddressSpace, and make KVM's listener use
> > > memory_region_to_address_space to figure out if it is for PV MMIO.
> > >
> > > To handle accesses from TCG, the PV AddressSpace can simply have just an
> > > alias to the actual MemoryRegion where the doorbell is.
> >
> > This is not really different from other eventfd flags like datamatch.
> > Separate address space is not appropriate here.
> > This is regular memory space, KVM eventfd simply has a flag that says
> > "guest is well behaved so please make eventfd go faster".
>
> Having a separate address space would match what you do in the kernel
> though.
Not really, in kernel the device is as usual on the MMIO
bus. The pv_mmio_bus is an extra datastructure to enable lookups where
length is not known in an efficient way. Userspace does not need to know
about these details.
> I just don't like functions with a dozen arguments... Can you just make
> datamatch and pv a single flags argument, as is the case with the KVM API?
>
> Paolo
Extra parameters are detected by compiler :)
I don't really care, anyone else objects to changing
datamatch to a flags argument?
Please let me know to avoid changing it back and forth.
--
MST
- [Qemu-devel] [PATCH v2 0/6] kvm: pci PORT IO MMIO and PV MMIO speed tests, Michael S. Tsirkin, 2013/04/04
- [Qemu-devel] [PATCH v2 4/6] pci: add pci test device, Michael S. Tsirkin, 2013/04/04
- [Qemu-devel] [PATCH v2 2/6] kvm: support any size for pio eventfd, Michael S. Tsirkin, 2013/04/04
- [Qemu-devel] [PATCH v2 1/6] kvm: remove unused APIs, Michael S. Tsirkin, 2013/04/04
- [Qemu-devel] [PATCH v2 3/6] kvm: support non datamatch ioeventfd, Michael S. Tsirkin, 2013/04/04
- [Qemu-devel] [PATCH v2 6/6] pci-testdev: add pv mmio test, Michael S. Tsirkin, 2013/04/04
- [Qemu-devel] [PATCH v2 5/6] kvm: add PV MMIO, Michael S. Tsirkin, 2013/04/04
- Re: [Qemu-devel] [PATCH v2 5/6] kvm: add PV MMIO, Peter Maydell, 2013/04/04