On 17/11/17 17:58, Alexey Kardashevskiy wrote:
> On 17/11/17 11:13, Alex Williamson wrote:
>> On Tue, 14 Nov 2017 10:47:12 +1100
>> Alexey Kardashevskiy <aik@xxxxxxxxx> wrote:
>>
>>> On 27/10/17 14:00, Alexey Kardashevskiy wrote:
>>>> This adds trace_map/trace_unmap tracepoints to spapr driver. Type1 already
>>>> uses these via the IOMMU API (iommu_map/__iommu_unmap).
>>>>
>>>> Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxxxx>
>>
>> Is this really legitimate to include tracepoints from a different
>> subsystem?> The vfio type1 backend gets these trace points by virtue of
>> it actually using the IOMMU API, it doesn't call them itself. I'm kind
>> of surprised these are actually available to be called from a module.
>
> They are explicitly exported:
>
> EXPORT_TRACEPOINT_SYMBOL_GPL(map);
> EXPORT_TRACEPOINT_SYMBOL_GPL(unmap);
>
> I would think this is for things like drivers/vfio/vfio_iommu_spapr_tce.c ,
> why else?...
>
>
>> I suspect the way to do this is probably to define our own tracepoints
>> in the vfio/spapr backend or insert tracepoints into the IOMMU layers
>> that that code calls into rather than masquerading as tracepoints from
>> a different subsystem. Right?
>
> This makes sense too. But it is going to be just cut-n-paste and some
> confusion -
> /sys/kernel/debug/tracing/events/iommu/map will still be present but
> won't work and
> /sys/kernel/debug/tracing/events/vfio/vfio_iommu_spapr_tce/map will.
>
> Judges? :)
Still nak? I discussed this locally, the conclusion was it is a matter of
taste and this proposal is not that disgusting. Thanks.
>
>
>
>> Thanks,
>>
>> Alex
>>
>>>> ---
>>>>
>>>> Example:
>>>> qemu-system-ppc-8655 [096] 724.662740: unmap: IOMMU: iova=0x000000003ffff000 size=4096 unmapped_size=4096
>>>> qemu-system-ppc-8656 [104] 724.970912: map: IOMMU: iova=0x0800000000000000 paddr=0x00007ffef7ff0000 size=65536
>>>> ---
>>>> drivers/vfio/vfio_iommu_spapr_tce.c | 12 ++++++++++--
>>>> 1 file changed, 10 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
>>>> index 63112c36ab2d..4531486c77c6 100644
>>>> --- a/drivers/vfio/vfio_iommu_spapr_tce.c
>>>> +++ b/drivers/vfio/vfio_iommu_spapr_tce.c
>>>> @@ -22,6 +22,7 @@
>>>> #include <linux/vmalloc.h>
>>>> #include <linux/sched/mm.h>
>>>> #include <linux/sched/signal.h>
>>>> +#include <trace/events/iommu.h>
>>>>
>>>> #include <asm/iommu.h>
>>>> #include <asm/tce.h>
>>>> @@ -502,17 +503,19 @@ static int tce_iommu_clear(struct tce_container *container,
>>>> struct iommu_table *tbl,
>>>> unsigned long entry, unsigned long pages)
>>>> {
>>>> - unsigned long oldhpa;
>>>> + unsigned long oldhpa, unmapped, firstentry = entry, totalpages = pages;
>>>> long ret;
>>>> enum dma_data_direction direction;
>>>>
>>>> - for ( ; pages; --pages, ++entry) {
>>>> + for (unmapped = 0; pages; --pages, ++entry) {
>>>> direction = DMA_NONE;
>>>> oldhpa = 0;
>>>> ret = iommu_tce_xchg(tbl, entry, &oldhpa, &direction);
>>>> if (ret)
>>>> continue;
>>>>
>>>> + ++unmapped;
>>>> +
>>>> if (direction == DMA_NONE)
>>>> continue;
>>>>
>>>> @@ -523,6 +526,9 @@ static int tce_iommu_clear(struct tce_container *container,
>>>>
>>>> tce_iommu_unuse_page(container, oldhpa);
>>>> }
>>>> + trace_unmap(firstentry << tbl->it_page_shift,
>>>> + totalpages << tbl->it_page_shift,
>>>> + unmapped << tbl->it_page_shift);
>>>>
>>>> return 0;
>>>> }
>>>> @@ -965,6 +971,8 @@ static long tce_iommu_ioctl(void *iommu_data,
>>>> direction);
>>>>
>>>> iommu_flush_tce(tbl);
>>>> + if (!ret)
>>>> + trace_map(param.iova, param.vaddr, param.size);
>>>>
>>>> return ret;
>>>> }
>>>>
>>>
>>>
>>
>
>
--
Alexey
