Re: [PATCH v2 8/9] qemu-kvm: Refresh MSI settings after vmload

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Apr 27, 2011 at 05:21:43PM +0200, Jan Kiszka wrote:
> On 2011-04-27 17:09, Michael S. Tsirkin wrote:
> > On Wed, Apr 27, 2011 at 04:39:53PM +0200, Jan Kiszka wrote:
> >> On 2011-04-27 16:30, Michael S. Tsirkin wrote:
> >>>>>> --- a/hw/pci.c
> >>>>>> +++ b/hw/pci.c
> >>>>>> @@ -34,6 +34,7 @@
> >>>>>>  #include "device-assignment.h"
> >>>>>>  #include "qemu-objects.h"
> >>>>>>  #include "range.h"
> >>>>>> +#include "msi.h"
> >>>>>>  
> >>>>>>  //#define DEBUG_PCI
> >>>>>>  #ifdef DEBUG_PCI
> >>>>>> @@ -342,6 +343,7 @@ static int get_pci_config_device(QEMUFile *f, void *pv, size_t size)
> >>>>>>      memcpy(s->config, config, size);
> >>>>>>  
> >>>>>>      pci_update_mappings(s);
> >>>>>> +    msi_post_load(s);
> >>>>>
> >>>>> Pls don't do this: I'm trying to keep just the core in
> >>>>> pci.c and all capabilities in separate files.
> >>>>> msix has msix_load, msi will just need one too,
> >>>>> and let all devices call that.
> >>>>>
> >>>>
> >>>> Preferred alternatives are...? Registering a vmstate for msi?
> >>>>
> >>>> Jan
> >>>
> >>> Add msi_load and call that from devices that need it.
> >>> Like msix_load does now.
> >>>
> >>
> >> msix_load/save are refactoring candidates IMHO. MSI-X has a real need
> >> for storing additional state information, so it should register its own
> >> subsection.
> > 
> > That's an implementation detail though, isn't it.
> > 
> >> I don't want to offload this burden to the devices also for
> >> MSI.
> >> From the devices' POV, why shouldn't msi_init suffice?
> >>
> >> Jan
> > 
> > One can also claim this about config writes:
> >     pci_bridge_write_config(d, address, val, len);
> >     pcie_cap_flr_write_config(d, address, val, len);
> >     pcie_cap_slot_write_config(d, address, val, len);
> >     msi_write_config(d, address, val, len);
> >     pcie_aer_write_config(d, address, val, len);
> > which arguably just duplicates the initialization sequence.
> > 
> > What I'm trying to do though is to keep it modular and
> > keep module inter-dependencies to a minimum,
> > so that pci is the core and msix depends on it
> > but not the other way around.
> 
> I still don't see the bigger benefit in saving a single bidirectional
> dependency at core level vs. saving additional callbacks at each and
> every MSI user. The latter is also a source for bugs.
> 
> Jan

Yes but let us be consistent with how e.g. config writes are
handled. As I said

> > What I think we should do is to add a pci subdirectory, move all
> > of the stuff there, move pci.c to pci/core.c and
> > add a high level module that depends on them all
> > and deals with all the capabilities.

Which will solve both issues without need for tradeoffs.

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