Re: [PATCH v2 06/19] util/vfio-helpers: Trace PCI I/O config accesses

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

Hi Philippe,

On 10/26/20 11:54 AM, Philippe Mathieu-Daudé wrote:
> We sometime get kernel panic with some devices on Aarch64
> hosts. Alex Williamson suggests it might be broken PCIe
> root complex. Add trace event to record the latest I/O
> access before crashing. In case, assert our accesses are
> aligned.
> 
> Reviewed-by: Fam Zheng <fam@euphon.net>
> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
>  util/vfio-helpers.c | 8 ++++++++
>  util/trace-events   | 2 ++
>  2 files changed, 10 insertions(+)
> 
> diff --git a/util/vfio-helpers.c b/util/vfio-helpers.c
> index 14a549510fe..1d4efafcaa4 100644
> --- a/util/vfio-helpers.c
> +++ b/util/vfio-helpers.c
> @@ -227,6 +227,10 @@ static int qemu_vfio_pci_read_config(QEMUVFIOState *s, void *buf,
>  {
>      int ret;
>  
> +    trace_qemu_vfio_pci_read_config(buf, ofs, size,
> +                                    s->config_region_info.offset,
> +                                    s->config_region_info.size);
> +    assert(QEMU_IS_ALIGNED(s->config_region_info.offset + ofs, size));
>      do {
>          ret = pread(s->device, buf, size, s->config_region_info.offset + ofs);
>      } while (ret == -1 && errno == EINTR);
> @@ -237,6 +241,10 @@ static int qemu_vfio_pci_write_config(QEMUVFIOState *s, void *buf, int size, int
>  {
>      int ret;
>  
> +    trace_qemu_vfio_pci_write_config(buf, ofs, size,
> +                                     s->config_region_info.offset,
> +                                     s->config_region_info.size);
> +    assert(QEMU_IS_ALIGNED(s->config_region_info.offset + ofs, size));
>      do {
>          ret = pwrite(s->device, buf, size, s->config_region_info.offset + ofs);
>      } while (ret == -1 && errno == EINTR);
> diff --git a/util/trace-events b/util/trace-events
> index 24c31803b01..c048f85f828 100644
> --- a/util/trace-events
> +++ b/util/trace-events
> @@ -85,3 +85,5 @@ qemu_vfio_new_mapping(void *s, void *host, size_t size, int index, uint64_t iova
>  qemu_vfio_do_mapping(void *s, void *host, size_t size, uint64_t iova) "s %p host %p size 0x%zx iova 0x%"PRIx64
>  qemu_vfio_dma_map(void *s, void *host, size_t size, bool temporary, uint64_t *iova) "s %p host %p size 0x%zx temporary %d iova %p"
>  qemu_vfio_dma_unmap(void *s, void *host) "s %p host %p"
> +qemu_vfio_pci_read_config(void *buf, int ofs, int size, uint64_t region_ofs, uint64_t region_size) "read cfg ptr %p ofs 0x%x size %d (region ofs 0x%"PRIx64" size %"PRId64")"
> +qemu_vfio_pci_write_config(void *buf, int ofs, int size, uint64_t region_ofs, uint64_t region_size) "write cfg ptr %p ofs 0x%x size %d (region ofs 0x%"PRIx64" size %"PRId64")"
I would personally use 0x%PRIx64 for the size too as generally done in
hw/vfio/trace-events .

Thanks

Eric
>