Re: [Qemu-devel] [PATCH v3 1/2] VFIO: Clear stale MSIx table during EEH reset

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

On Fri, Mar 27, 2015 at 05:00:25PM +1100, David Gibson wrote:
>On Thu, Mar 26, 2015 at 04:35:01PM +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 introduces function vfio_eeh_pe_reset(), which is called
>> by sPAPR when asserting hot or fundamental reset, to clear 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>
>> ---
>>  hw/ppc/spapr_pci_vfio.c | 13 +++++++++----
>>  hw/vfio/Makefile.objs   |  6 +++++-
>>  hw/vfio/pci-stub.c      | 16 ++++++++++++++++
>>  hw/vfio/pci.c           | 36 ++++++++++++++++++++++++++++++++++++
>>  include/hw/vfio/vfio.h  |  2 ++
>>  5 files changed, 68 insertions(+), 5 deletions(-)
>>  create mode 100644 hw/vfio/pci-stub.c
>> 
>> diff --git a/hw/ppc/spapr_pci_vfio.c b/hw/ppc/spapr_pci_vfio.c
>> index 99a1be5..6fa3afe 100644
>> --- a/hw/ppc/spapr_pci_vfio.c
>> +++ b/hw/ppc/spapr_pci_vfio.c
>> @@ -151,19 +151,24 @@ static int spapr_phb_vfio_eeh_reset(sPAPRPHBState *sphb, int option)
>>      switch (option) {
>>      case RTAS_SLOT_RESET_DEACTIVATE:
>>          op.op = VFIO_EEH_PE_RESET_DEACTIVATE;
>> +        ret = vfio_container_ioctl(&svphb->phb.iommu_as,
>> +                                   svphb->iommugroupid,
>> +                                   VFIO_EEH_PE_OP, &op);
>>          break;
>>      case RTAS_SLOT_RESET_HOT:
>> -        op.op = VFIO_EEH_PE_RESET_HOT;
>> +        ret = vfio_eeh_pe_reset(&svphb->phb.iommu_as,
>> +                                svphb->iommugroupid,
>> +                                VFIO_EEH_PE_RESET_HOT);
>>          break;
>>      case RTAS_SLOT_RESET_FUNDAMENTAL:
>> -        op.op = VFIO_EEH_PE_RESET_FUNDAMENTAL;
>> +        ret = vfio_eeh_pe_reset(&svphb->phb.iommu_as,
>> +                                svphb->iommugroupid,
>> +                                VFIO_EEH_PE_RESET_FUNDAMENTAL);
>>          break;
>>      default:
>>          return RTAS_OUT_PARAM_ERROR;
>>      }
>>  
>> -    ret = vfio_container_ioctl(&svphb->phb.iommu_as, svphb->iommugroupid,
>> -                               VFIO_EEH_PE_OP, &op);
>>      if (ret < 0) {
>>          return RTAS_OUT_HW_ERROR;
>>      }
>> 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/pci-stub.c b/hw/vfio/pci-stub.c
>> new file mode 100644
>> index 0000000..f317c1e
>> --- /dev/null
>> +++ b/hw/vfio/pci-stub.c
>> @@ -0,0 +1,16 @@
>> +/*
>> + * To include the file on !CONFIG_PCI
>> + *
>> + * This work is licensed under the terms of the GNU GPL, version 2.  See
>> + * the COPYING file in the top-level directory.
>> + */
>> +
>> +#include <linux/vfio.h>
>> +
>> +#include "exec/memory.h"
>> +#include "hw/vfio/vfio.h"
>> +
>> +int vfio_eeh_pe_reset(AddressSpace *as, int32_t groupid, uint32_t option)
>> +{
>> +    return -1;
>> +}
>
>This doesn't seem quite right.  AFAICT the only caller of
>vfio_eeh_pe_reset() is in spapr_pci_vfio.c, which is only built if
>CONFIG_PCI is enabled.  So if there needed to be !PCI stubs, I'd
>expect them further up the call stack.
>

Or we simply drop the stub for !CONFIG_PCI if Alex.W agree. Alex, what's
your opnion?

Thanks,
Gavin

>> +int vfio_eeh_pe_reset(AddressSpace *as, int32_t groupid, uint32_t option)
>> +{
>> +    VFIOGroup *group;
>> +    VFIODevice *vbasedev;
>> +    VFIOPCIDevice *vdev;
>> +    struct vfio_eeh_pe_op op = {
>> +        .argsz = sizeof(op),
>> +        .op = option
>> +    };
>> +
>> +    group = vfio_get_group(groupid, as);
>> +    if (!group) {
>> +        error_report("vfio: group %d not found\n", groupid);
>> +        return -1;
>> +    }
>> +
>> +    /*
>> +     * The MSIx table will be cleaned out by reset. We need
>> +     * disable it so that it can be reenabled properly. Also,
>> +     * the cached MSIx table should be cleared as it's not
>> +     * reflecting the contents in hardware.
>> +     */
>> +    QLIST_FOREACH(vbasedev, &group->device_list, next) {
>> +        vdev = container_of(vbasedev, VFIOPCIDevice, vbasedev);
>> +        if (msix_enabled(&vdev->pdev)) {
>> +            vfio_disable_msix(vdev);
>> +        }
>> +
>> +        msix_reset(&vdev->pdev);
>> +    }
>> +
>> +    vfio_put_group(group);
>> +
>> +    return vfio_container_ioctl(as, groupid, VFIO_EEH_PE_OP, &op);
>> +}
>
>This is much better than the vfio_eeh_event stuff().
>
>-- 
>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