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

[David Gibson <david@gibson.dropbear.id.au>]

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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().


> +            error_report("vfio: cannot handle EEH event on group %d\n",
> +                         groupid);
> +            return -1;
> +        }
> +
>          break;
>      default:
>          /* Return an error on unknown requests */
> diff --git a/hw/vfio/pci-stub.c b/hw/vfio/pci-stub.c
> new file mode 100644
> index 0000000..7726a7a
> --- /dev/null
> +++ b/hw/vfio/pci-stub.c
> @@ -0,0 +1,17 @@
> +/*
> + * 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_container_eeh_event(AddressSpace *as, int32_t groupid,
> +                             struct vfio_eeh_pe_op *op)
> +{
> +    return -1;
> +}
> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> index 6b80539..fca1edc 100644
> --- a/hw/vfio/pci.c
> +++ b/hw/vfio/pci.c
> @@ -3319,6 +3319,44 @@ static void vfio_unregister_req_notifier(VFIOPCIDevice *vdev)
>      vdev->req_enabled = false;
>  }
>  
> +int vfio_container_eeh_event(AddressSpace *as, int32_t groupid,
> +                             struct vfio_eeh_pe_op *op)
> +{
> +    VFIOGroup *group;
> +    VFIODevice *vbasedev;
> +    VFIOPCIDevice *vdev;
> +
> +    group = vfio_get_group(groupid, as);
> +    if (!group) {
> +        error_report("vfio: group %d not found\n", groupid);
> +        return -1;
> +    }
> +
> +    switch (op->op) {
> +    case VFIO_EEH_PE_RESET_HOT:
> +    case VFIO_EEH_PE_RESET_FUNDAMENTAL:
> +        /*
> +         * 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);
> +        }
> +
> +        break;
> +    }
> +
> +    vfio_put_group(group);
> +    return 0;
> +}
> +
>  static int vfio_initfn(PCIDevice *pdev)
>  {
>      VFIOPCIDevice *vdev = DO_UPCAST(VFIOPCIDevice, pdev, pdev);
> diff --git a/include/hw/vfio/vfio.h b/include/hw/vfio/vfio.h
> index 0b26cd8..e9a3abb 100644
> --- a/include/hw/vfio/vfio.h
> +++ b/include/hw/vfio/vfio.h
> @@ -5,5 +5,7 @@
>  
>  extern int vfio_container_ioctl(AddressSpace *as, int32_t groupid,
>                                  int req, void *param);
> +extern int vfio_container_eeh_event(AddressSpace *as, int32_t groupid,
> +                                    struct vfio_eeh_pe_op *op);
>  
>  #endif

-- 
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

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