Re: [PATCH] vhost-vdpa: skip TPM CRB memory section

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Nov 22, 2022 at 06:53:49PM +0400, marcandre.lureau@redhat.com wrote:
> From: Marc-André Lureau <marcandre.lureau@redhat.com>
> 
> 851d6d1a0f ("vfio/common: remove spurious tpm-crb-cmd misalignment
> warning") removed the warning on vfio_listener_region_add() path.
> 
> An error is reported for vhost-vdpa case:
> qemu-kvm: vhost_vdpa_listener_region_add received unaligned region
> 
> Skip the CRB device.
> 
> Fixes:
> https://bugzilla.redhat.com/show_bug.cgi?id=2141965
> 
> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> ---
>  hw/virtio/vhost-vdpa.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c
> index 7468e44b87..9d7206e4b8 100644
> --- a/hw/virtio/vhost-vdpa.c
> +++ b/hw/virtio/vhost-vdpa.c
> @@ -19,6 +19,7 @@
>  #include "hw/virtio/virtio-net.h"
>  #include "hw/virtio/vhost-shadow-virtqueue.h"
>  #include "hw/virtio/vhost-vdpa.h"
> +#include "sysemu/tpm.h"
>  #include "exec/address-spaces.h"
>  #include "migration/blocker.h"
>  #include "qemu/cutils.h"
> @@ -46,6 +47,11 @@ static bool vhost_vdpa_listener_skipped_section(MemoryRegionSection *section,
>  {
>      Int128 llend;
>  
> +    if (TPM_IS_CRB(section->mr->owner)) {
> +        /* The CRB command buffer has its base address unaligned. */
> +        return true;
> +    }
> +

Quite a hack. We can't really keep adding dependency on random devices
to vhost. And would you add hacks like this to listeners?
Pls figure out what's special about this buffer.
Also if this section is unaligned then doesn't it break up
other aligned sections?


>      if ((!memory_region_is_ram(section->mr) &&
>           !memory_region_is_iommu(section->mr)) ||
>          memory_region_is_protected(section->mr) ||
> -- 
> 2.38.1