Re: [Qemu-devel] [Qemu-ppc] [PATCH v2 1/3] VFIO: Clear stale MSIx table during EEH reset

[Gavin Shan <gwshan@linux.vnet.ibm.com>]

On Mon, Mar 23, 2015 at 04:06:56PM +1100, David Gibson wrote:
>On Fri, Mar 20, 2015 at 05:27:29PM +1100, Gavin Shan wrote:
>> On Fri, Mar 20, 2015 at 05:04:01PM +1100, David Gibson wrote:
>> >On Tue, Mar 17, 2015 at 03:31:24AM +1100, Gavin Shan wrote:
>> >> The PCI device MSIx table is cleaned out in hardware after EEH PE
>> >> reset. However, we still hold the stale MSIx entries in QEMU, which
>> >> should be cleared accordingly. Otherwise, we will run into another
>> >> (recursive) EEH error and the PCI devices contained in the PE have
>> >> to be offlined exceptionally.
>> >> 
>> >> The patch clears stale MSIx table before EEH PE reset so that MSIx
>> >> table could be restored properly after EEH PE reset.
>> >> 
>> >> Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
>> >> ---
>> >> v2: vfio_container_eeh_event() stub for !CONFIG_PCI and separate
>> >>     error message for this function. Dropped vfio_put_group()
>> >>     on NULL group
>> >> ---
>> >>  hw/vfio/Makefile.objs  |  6 +++++-
>> >>  hw/vfio/common.c       |  7 +++++++
>> >>  hw/vfio/pci-stub.c     | 17 +++++++++++++++++
>> >>  hw/vfio/pci.c          | 38 ++++++++++++++++++++++++++++++++++++++
>> >>  include/hw/vfio/vfio.h |  2 ++
>> >>  5 files changed, 69 insertions(+), 1 deletion(-)
>> >>  create mode 100644 hw/vfio/pci-stub.c
>> >> 
>> >> diff --git a/hw/vfio/Makefile.objs b/hw/vfio/Makefile.objs
>> >> index e31f30e..1b8a065 100644
>> >> --- a/hw/vfio/Makefile.objs
>> >> +++ b/hw/vfio/Makefile.objs
>> >> @@ -1,4 +1,8 @@
>> >>  ifeq ($(CONFIG_LINUX), y)
>> >>  obj-$(CONFIG_SOFTMMU) += common.o
>> >> -obj-$(CONFIG_PCI) += pci.o
>> >> +ifeq ($(CONFIG_PCI), y)
>> >> +obj-y += pci.o
>> >> +else
>> >> +obj-y += pci-stub.o
>> >> +endif
>> >>  endif
>> >> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
>> >> index 148eb53..ed07814 100644
>> >> --- a/hw/vfio/common.c
>> >> +++ b/hw/vfio/common.c
>> >> @@ -949,7 +949,14 @@ int vfio_container_ioctl(AddressSpace *as, int32_t groupid,
>> >>      switch (req) {
>> >>      case VFIO_CHECK_EXTENSION:
>> >>      case VFIO_IOMMU_SPAPR_TCE_GET_INFO:
>> >> +        break;
>> >>      case VFIO_EEH_PE_OP:
>> >> +        if (vfio_container_eeh_event(as, groupid, param) != 0) {
>> >
>> >I really dislike the idea of having an arbitrarily complex side effect
>> >from a function whose name suggest's it's just a trivial wrapper
>> >around the ioctl().
>> >
>> 
>> Ok. I guess you would like putting the complex in the callers of
>> vfio_container_ioctl().
>
>Well.. maybe.  I'd also be happy if helper functions were implemeneted
>which both called the ioctl() and did the other necessary pieces.
>They should just be called something that indicates their full
>function, not a name which suggests they're just an ioctl wrapper.
>

Indeed, vfio_container_ioctl() isn't indicating what the function is doing.
How about renaming it to vfio_container_event_and_ioctl()? I'm always bad
at giving a good function name :)

Thanks,
Gavin

>> All those callers are implemtend in sPAPR
>> platform (spapr_pci_vfio.c). I didn't put the logic there because:
>> 
>> - VFIOPCIDevice is invisible to sPAPR platform.
>
>It seems kind of silly that VFIOPCIDevice isn't visible to
>spapr_pci_vfio.c.
>
>> - We can't tell one particular PCI device attached to sPAPRPHBState
>>   is the basement of VFIOPCIDevice, or emulated PCI device.
>
>I'm not sure what you mean by that.
>
>
>-- 
>David Gibson			| I'll have my music baroque, and my code
>david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
>				| _way_ _around_!
>http://www.ozlabs.org/~dgibson