Re: [PATCH v3 1/3] msix/hmp: add hmp interface to dump MSI-X info

[Markus Armbruster]

Dongli Zhang <dongli.zhang@oracle.com> writes:

> This patch is to add the HMP interface to dump MSI-X table and PBA, in
> order to help diagnose the loss of IRQ issue in VM (e.g., if an MSI-X
> vector is erroneously masked permanently). Here is the example with
> vhost-scsi:
>
> (qemu) info msix /machine/peripheral/vscsi0
> Msg L.Addr Msg U.Addr Msg Data   Vect Ctrl
> 0xfee00000 0x00000000 0x00004041 0x00000000
> 0xfee00000 0x00000000 0x00004051 0x00000000
> 0xfee00000 0x00000000 0x00004061 0x00000000
> 0xfee00000 0x00000000 0x00004071 0x00000000
> 0xfee01000 0x00000000 0x000040b1 0x00000000
> 0xfee02000 0x00000000 0x000040c1 0x00000000
> 0xfee03000 0x00000000 0x000040d1 0x00000000
>
> MSI-X PBA
> 0 0 0 0 0 0 0
>
> Since the number of MSI-X entries is not determined and might be very
> large, it is sometimes inappropriate to dump via QMP.

Why?  What makes HMP different?

> Therefore, this patch dumps MSI-X information only via HMP, which is
> similar to the implementation of hmp_info_mem().
>
> Cc: Jason Wang <jasowang@redhat.com>
> Cc: Joe Jin <joe.jin@oracle.com>
> Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
> Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> Acked-by: Jason Wang <jasowang@redhat.com>