Re: [PATCH v2 2/2] vfio/common: Add trace point when a MMIO RAM section less than PAGE_SIZE

[Eric Auger <eric.auger@redhat.com>]

Hi Kunkun,

On 9/14/21 3:53 AM, Kunkun Jiang wrote:
> The MSI-X structures of some devices and other non-MSI-X structures
> are in the same BAR. They may share one host page, especially in the
may be in the same bar?
> case of large page granularity, such as 64K.
>
> For example, MSIX-Table size of 82599 NIC is 0x30 and the offset in
> Bar 3(size 64KB) is 0x0. If host page size is 64KB.
remove the '.'
In that case wouldn't the symptom be the same with a 4kB page?
> vfio_listener_region_add() will be called to map the remaining range
> (0x30-0xffff). And it will return early at
> 'int128_ge((int128_make64(iova), llend))' and hasn't any message.
s/and hasn't any message /without any message
> Let's add a trace point to informed users like commit 5c08600547c0
s/informed/inform
> ("vfio: Use a trace point when a RAM section cannot be DMA mapped")
> did.
>
> Signed-off-by: Kunkun Jiang <jiangkunkun@huawei.com>
> ---
>  hw/vfio/common.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> index 8728d4d5c2..2fc6213c0f 100644
> --- a/hw/vfio/common.c
> +++ b/hw/vfio/common.c
> @@ -892,6 +892,13 @@ static void vfio_listener_region_add(MemoryListener *listener,
>      llend = int128_and(llend, int128_exts64(qemu_real_host_page_mask));
>  
>      if (int128_ge(int128_make64(iova), llend)) {
> +        if (memory_region_is_ram_device(section->mr)) {
> +            trace_vfio_listener_region_add_no_dma_map(
> +                memory_region_name(section->mr),
> +                section->offset_within_address_space,
> +                int128_getlo(section->size),
> +                qemu_real_host_page_size);
> +        }
>          return;
>      }
>      end = int128_get64(int128_sub(llend, int128_one()));
Thanks

Eric