On 19/09/17 01:23 PM, Christian König wrote:
Am 19.09.2017 um 19:20 schrieb Tom St Denis:
On 19/09/17 01:18 PM, Christian König wrote:
Am 19.09.2017 um 19:14 schrieb Tom St Denis:
On 19/09/17 01:10 PM, Christian König wrote:
As far as I know we don't need #ifdefs cause there are dummy
functions when IOMMU is not compiled in.
But this patch is a NAK since it circumvents the /dev/mem
restriction when IOMMU is disabled and that is not something we can
easily allow.
I raised this objection 24 hours ago and was told to go ahead with
the read/write methods anyways.
Short of making a list of mappings/allocations in the ttm layer I
have no idea how we would track this in the non-iommu case which
means the entire iova debugfs entry should have been NAK'ed in the
first place.
I'm open to suggestions.
As long as IOMMU is enabled the entry is perfectly fine, cause only
memory mapped to the IOMMU is accessible to the GPU and so accessible
using the debugfs entry as well.
On devices where there's no translation (e.g. Carrizo) does the iommu
layer track mappings? I'm wondering if on those I could seek outside
of boundaries and read system memory anyways.
Why do you think there isn't any translation on CZ? I mean the whole ATC
thing uses the IOMMU (v2 in this case) on APUs.
On my Carrizo devel system (A12-9800) the GPU dma addresses are physical
addresses. I only first saw iommu with APUs enabled on Raven.
I'll see if I can read non-mapped pages via the iova file on my Carrizo.
Only when IOMMU is disabled we can't go this way cause we can't know
which memory is mapped to the driver and which isn't (or could we
somehow track this?).
I suggest to not create the file in the first place if IOMMU is
disabled.
I could easily do this (basically check if the domain is not null at
debugfs init time).
Yeah, please do this for now.
I mean it would be great to have this interface even with IOMMU
disabled, but of hand I can't think of a way to allow this.
Sent to the list already. Tested with enabled/disabled. Seems to work
for me.
Tom
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