Re: [Qemu-devel] [PATCH v2] vhost: Allow adjoining regions

[Alex Williamson]

On Fri, 23 Mar 2018 15:39:39 +0000
"Dr. David Alan Gilbert (git)" <address@hidden> wrote:

> From: "Dr. David Alan Gilbert" <address@hidden>
> 
> My rework of section adding combines overlapping or adjoining regions,
> but checks they're actually the same underlying RAM block.
> Fix the case where two blocks adjoin but don't overlap; that new region
> should get added (but not combined), but my previous patch was disallowing it.
> 
> Fixes: c1ece84e7c9
> 
> Reported-by: Alex Williamson <address@hidden>
> Signed-off-by: Dr. David Alan Gilbert <address@hidden>
> ---


Ping?  This error report is a regression and should be considered for
2.12.

Tested-by: Alex Williamson <address@hidden>


>  hw/virtio/vhost.c | 13 +++++++++----
>  1 file changed, 9 insertions(+), 4 deletions(-)
> 
> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> index 250f886acb..2a720cca3d 100644
> --- a/hw/virtio/vhost.c
> +++ b/hw/virtio/vhost.c
> @@ -595,10 +595,15 @@ static void vhost_region_add_section(struct vhost_dev 
> *dev,
>                                          
> prev_sec->offset_within_address_space,
>                                          prev_sec->offset_within_region);
>              } else {
> -                error_report("%s: Overlapping but not coherent sections "
> -                             "at %"PRIx64,
> -                             __func__, mrs_gpa);
> -                return;
> +                /* adjoining regions are fine, but overlapping ones with
> +                 * different blocks/offsets shouldn't happen
> +                 */
> +                if (mrs_gpa != prev_gpa_end + 1) {
> +                    error_report("%s: Overlapping but not coherent sections "
> +                                 "at %"PRIx64,
> +                                 __func__, mrs_gpa);
> +                    return;
> +                }
>              }
>          }
>      }