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

[Kunkun Jiang]

Hi Alex,

On 2021/9/9 4:45, Alex Williamson wrote:
> On Fri, 3 Sep 2021 17:36:11 +0800
> Kunkun Jiang <jiangkunkun@huawei.com> 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
> > case of large page granularity, suck as 64K.
> s/suck/such/
ok
> > 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.
> > vfio_listenerregion_add() will be called to map the remaining range
> s/vfio_listenerregion_add/vfio_listener_region_add/
ok
> > (0x30-0xffff). And it will return early at
> > 'int128_ge((int128_make64(iova), llend))' and hasn't any message.
> > Let's add a trace point to informed users like 5c08600547c did.
> Please use the following syntax for referencing previous commits
> (12-char sha1 is standard):
>
>    commit 5c08600547c0 ("vfio: Use a trace point when a RAM section
>    cannot be DMA mapped")
Thank you for your reply. I will correct it in V2.

Thanks,
Kunkun Jiang
> Thanks,
> Alex
>
> > 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()));
> .