Re: [PATCH v4 16/25] vfio: Add Error** argument to .set_dirty_page_tracking() handler

[Cédric Le Goater]

On 3/7/24 09:09, Eric Auger wrote:
> Hi Cédric,
>
> On 3/6/24 14:34, Cédric Le Goater wrote:
> > We will use the Error object to improve error reporting in the
> > .log_global*() handlers of VFIO. Add documentation while at it.
> >
> > Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> > Signed-off-by: Cédric Le Goater <clg@redhat.com>
> > ---
> >
> >   Changes in v3:
> >
> >   - Use error_setg_errno() in vfio_legacy_set_dirty_page_tracking()
> >   
> >   include/hw/vfio/vfio-container-base.h | 18 ++++++++++++++++--
> >   hw/vfio/common.c                      |  4 ++--
> >   hw/vfio/container-base.c              |  4 ++--
> >   hw/vfio/container.c                   |  6 +++---
> >   4 files changed, 23 insertions(+), 9 deletions(-)
> >
> > diff --git a/include/hw/vfio/vfio-container-base.h 
> > b/include/hw/vfio/vfio-container-base.h
> > index 
> > 3582d5f97a37877b2adfc0d0b06996c82403f8b7..c76984654a596e3016a8cf833e10143eb872e102
> >  100644
> > --- a/include/hw/vfio/vfio-container-base.h
> > +++ b/include/hw/vfio/vfio-container-base.h
> > @@ -82,7 +82,7 @@ int vfio_container_add_section_window(VFIOContainerBase 
> > *bcontainer,
> >   void vfio_container_del_section_window(VFIOContainerBase *bcontainer,
> >                                          MemoryRegionSection *section);
> >   int vfio_container_set_dirty_page_tracking(VFIOContainerBase *bcontainer,
> > -                                           bool start);
> > +                                           bool start, Error **errp);
> >   int vfio_container_query_dirty_bitmap(const VFIOContainerBase *bcontainer,
> >                                         VFIOBitmap *vbmap,
> >                                         hwaddr iova, hwaddr size);
> > @@ -121,9 +121,23 @@ struct VFIOIOMMUClass {
> >       int (*attach_device)(const char *name, VFIODevice *vbasedev,
> >                            AddressSpace *as, Error **errp);
> >       void (*detach_device)(VFIODevice *vbasedev);
> > +
> >       /* migration feature */
> > +
> > +    /**
> > +     * @set_dirty_page_tracking
> > +     *
> > +     * Start or stop dirty pages tracking on VFIO container
> > +     *
> > +     * @bcontainer: #VFIOContainerBase on which to de/activate dirty
> > +     *              pages tracking
> s/pages/page?

yep

> for my education is the "#"VFIOContainerBase formalized somewhere?

It's QEMU specific. See 4cf41794411f ("docs: tweak kernel-doc for QEMU
coding standards").

> +     * @start: indicates whether to start or stop dirty pages tracking
> > +     * @errp: pointer to Error*, to store an error if it happens.
> > +     *
> > +     * Returns zero to indicate success and negative for error
> > +     */
> >       int (*set_dirty_page_tracking)(const VFIOContainerBase *bcontainer,
> > -                                   bool start);
> > +                                   bool start, Error **errp);
> >       int (*query_dirty_bitmap)(const VFIOContainerBase *bcontainer,
> >                                 VFIOBitmap *vbmap,
> >                                 hwaddr iova, hwaddr size);
> > diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> > index 
> > 800ba0aeac84b8dcc83b042bb70c37b4bf78d3f4..5598a508399a6c0b3a20ba17311cbe83d84250c5
> >  100644
> > --- a/hw/vfio/common.c
> > +++ b/hw/vfio/common.c
> > @@ -1085,7 +1085,7 @@ static bool vfio_listener_log_global_start(MemoryListener 
> > *listener,
> >       if (vfio_devices_all_device_dirty_tracking(bcontainer)) {
> >           ret = vfio_devices_dma_logging_start(bcontainer);
> >       } else {
> > -        ret = vfio_container_set_dirty_page_tracking(bcontainer, true);
> > +        ret = vfio_container_set_dirty_page_tracking(bcontainer, true, NULL);
> It is not obvious why we don't pass errp here. Also there is ana
> error_report below. Why isn't the error propagated? (not related to your
> patch though)

When I started this series, I was trying to find a way to introduce
progressively the changes and this patch is preparing ground for
what is coming next. It could be merged with the following if you prefer.


Thanks,

C.




> >       }
> >   
> >       if (ret) {
> > @@ -1105,7 +1105,7 @@ static void vfio_listener_log_global_stop(MemoryListener 
> > *listener)
> >       if (vfio_devices_all_device_dirty_tracking(bcontainer)) {
> >           vfio_devices_dma_logging_stop(bcontainer);
> >       } else {
> > -        ret = vfio_container_set_dirty_page_tracking(bcontainer, false);
> > +        ret = vfio_container_set_dirty_page_tracking(bcontainer, false, NULL);
> >       }
> >   
> >       if (ret) {
> > diff --git a/hw/vfio/container-base.c b/hw/vfio/container-base.c
> > index 
> > 913ae49077c4f09b7b27517c1231cfbe4befb7fb..7c0764121d24b02b6c4e66e368d7dff78a6d65aa
> >  100644
> > --- a/hw/vfio/container-base.c
> > +++ b/hw/vfio/container-base.c
> > @@ -53,14 +53,14 @@ void vfio_container_del_section_window(VFIOContainerBase 
> > *bcontainer,
> >   }
> >   
> >   int vfio_container_set_dirty_page_tracking(VFIOContainerBase *bcontainer,
> > -                                           bool start)
> > +                                           bool start, Error **errp)
> >   {
> >       if (!bcontainer->dirty_pages_supported) {
> >           return 0;
> >       }
> >   
> >       g_assert(bcontainer->ops->set_dirty_page_tracking);
> > -    return bcontainer->ops->set_dirty_page_tracking(bcontainer, start);
> > +    return bcontainer->ops->set_dirty_page_tracking(bcontainer, start, errp);
> >   }
> >   
> >   int vfio_container_query_dirty_bitmap(const VFIOContainerBase *bcontainer,
> > diff --git a/hw/vfio/container.c b/hw/vfio/container.c
> > index 
> > 096d77eac3946a9c38fc2a98116b93353f71f06e..6524575aeddcea8470b5fd10caf57475088d1813
> >  100644
> > --- a/hw/vfio/container.c
> > +++ b/hw/vfio/container.c
> > @@ -210,7 +210,7 @@ static int vfio_legacy_dma_map(const VFIOContainerBase 
> > *bcontainer, hwaddr iova,
> >   
> >   static int
> >   vfio_legacy_set_dirty_page_tracking(const VFIOContainerBase *bcontainer,
> > -                                    bool start)
> > +                                    bool start, Error **errp)
> >   {
> >       const VFIOContainer *container = container_of(bcontainer, VFIOContainer,
> >                                                     bcontainer);
> > @@ -228,8 +228,8 @@ vfio_legacy_set_dirty_page_tracking(const VFIOContainerBase 
> > *bcontainer,
> >       ret = ioctl(container->fd, VFIO_IOMMU_DIRTY_PAGES, &dirty);
> >       if (ret) {
> >           ret = -errno;
> > -        error_report("Failed to set dirty tracking flag 0x%x errno: %d",
> > -                     dirty.flags, errno);
> > +        error_setg_errno(errp, errno, "Failed to set dirty tracking flag 0x%x",
> > +                         dirty.flags);
> >       }
> >   
> >       return ret;
>
> Thanks
>
> Eric