Re: [Qemu-devel] [PATCH for v1.0 1/3] msix: track function masked in pci device state

[Cam Macdonell]

On Sun, Dec 4, 2011 at 3:20 AM, Michael S. Tsirkin <address@hidden> wrote:
> On Fri, Dec 02, 2011 at 04:34:21PM -0700, Cam Macdonell wrote:
>> Based on a git bisect, this patch breaks msi-x interrupt delivery in
>> the ivshmem device.
>
> I think the following should fix it. Compiled-only -
> could you pls check? If yes let's apply to the stable branch.

Thanks for the patch Michael.

It addresses the need for msix_write_config() to be called, but the
addition of the msix_reset() is causing a reset of the vectors after
they've been initialized in pci_ivshmem_init().  So, interrupts still
aren't delivered with this patch applied as it is.

In particular, a reset occurs after pci_ivshmem_init runs, so the
msix_entry_used array is reset to 0s, which causes the interrupt
delivery to fail.

If I comment out the msix_reset(), then interrupts are delivered.
Would the reset be caused by a bug in the guest driver?  or do I need
to reconfigure the msix after reset?  I'm unclear as to the proper
behaviour after a reset.

Thanks,
Cam

>
> -->
>
> ivshmem: add missing msix calls
>
> ivshmem used msix but didn't call it on either reset or
> config write paths. This used to partically work since
> guests don't use all of msi-x configuration fields,
> and reset is rarely used, but the patch 'msix: track function masked
> in pci device state' broke that. Fix by adding appropriate calls.
>
> Signed-off-by: Michael S. Tsirkin <address@hidden>
>
> --
>
> diff --git a/hw/ivshmem.c b/hw/ivshmem.c
> index 242fbea..3680c0f 100644
> --- a/hw/ivshmem.c
> +++ b/hw/ivshmem.c
> @@ -505,6 +505,7 @@ static void ivshmem_reset(DeviceState *d)
>     IVShmemState *s = DO_UPCAST(IVShmemState, dev.qdev, d);
>
>     s->intrstatus = 0;
> +    msix_reset(&s->dev);
>     return;
>  }
>
> @@ -610,6 +611,13 @@ static int ivshmem_load(QEMUFile* f, void *opaque, int 
> version_id)
>     return 0;
>  }
>
> +static void ivshmem_write_config(PCIDevice *pci_dev, uint32_t address,
> +                                uint32_t val, int len)
> +{
> +    pci_default_write_config(pci_dev, address, val, len);
> +    msix_write_config(pci_dev, address, val, len);
> +}
> +
>  static int pci_ivshmem_init(PCIDevice *dev)
>  {
>     IVShmemState *s = DO_UPCAST(IVShmemState, dev, dev);
> @@ -734,6 +742,8 @@ static int pci_ivshmem_init(PCIDevice *dev)
>
>     }
>
> +    s->dev.config_write = ivshmem_write_config;
> +
>     return 0;
>  }
>
>