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In __arm_v7s_alloc_table function:
iommu call kmem_cache_alloc to allocate page table, this function
allocate memory may fail, when kmem_cache_alloc fails to allocate
table, call virt_to_phys will be abnomal and return unexpected phys
and goto out_free, then call kmem_cache_free to release table will
trigger KE, __get_free_pages and free_pages have similar problem,
so add error handle for page table allocation failure.
Fixes: 29859aeb8a ("iommu/io-pgtable-arm-v7s: Abort allocation when table address overflows the PTE")
Signed-off-by: Yunfei Wang <yf.wang@mediatek.com>
Cc: <stable@vger.kernel.org> # 5.10.*
Acked-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/20211207113315.29109-1-yf.wang@mediatek.com
Signed-off-by: Will Deacon <will@kernel.org>
Previously io-pgtable merely passed the iommu_iotlb_gather pointer
through to helpers, but now it has grown its own direct dereference.
This turns out to break the build for !IOMMU_API configs where the
structure only has a dummy definition. It will probably also crash
drivers who don't use the gather mechanism and simply pass in NULL.
Wrap this dereference in a suitable helper which can both be stubbed
out for !IOMMU_API and encapsulate a NULL check otherwise.
Fixes: 7a7c5badf8 ("iommu: Indicate queued flushes via gather data")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/83672ee76f6405c82845a55c148fa836f56fbbc1.1629465282.git.robin.murphy@arm.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
IO_PGTABLE_QUIRK_NON_STRICT was never a very comfortable fit, since it's
not a quirk of the pagetable format itself. Now that we have a more
appropriate way to convey non-strict unmaps, though, this last of the
non-quirk quirks can also go, and with the flush queue code also now
enforcing its own ordering we can have a lovely cleanup all round.
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/155b5c621cd8936472e273a8b07a182f62c6c20d.1628682049.git.robin.murphy@arm.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
The standard input iova bits is 32. MediaTek quad the lvl1 pagetable
(4 * lvl1). No change for lvl2 pagetable. Then the iova bits can reach
34bit.
Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Link: https://lore.kernel.org/r/20210111111914.22211-14-yong.wu@mediatek.com
Signed-off-by: Will Deacon <will@kernel.org>
Add "cfg" as a parameter for some macros. This is a preparing patch for
mediatek extend the lvl1 pgtable. No functional change.
Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Acked-by: Will Deacon <will@kernel.org>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Link: https://lore.kernel.org/r/20210111111914.22211-13-yong.wu@mediatek.com
Signed-off-by: Will Deacon <will@kernel.org>
The current _ARM_V7S_LVL_BITS/ARM_V7S_LVL_SHIFT use a formula to calculate
the corresponding value for level1 and level2 to pretend the code sane.
Actually their level1 and level2 values are different from each other.
This patch only clarify the two macro. No functional change.
Suggested-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Link: https://lore.kernel.org/r/20210111111914.22211-12-yong.wu@mediatek.com
Signed-off-by: Will Deacon <will@kernel.org>
MediaTek extend the bit5 in lvl1 and lvl2 descriptor as PA34.
Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Acked-by: Will Deacon <will@kernel.org>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Link: https://lore.kernel.org/r/20210111111914.22211-11-yong.wu@mediatek.com
Signed-off-by: Will Deacon <will@kernel.org>
Use the ias for the valid iova checking in arm_v7s_unmap. This is a
preparing patch for supporting iova 34bit for MediaTek.
Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Link: https://lore.kernel.org/r/20210111111914.22211-10-yong.wu@mediatek.com
Signed-off-by: Will Deacon <will@kernel.org>
The only user of tlb_flush_leaf is a particularly hairy corner of the
Arm short-descriptor code, which wants a synchronous invalidation to
minimise the races inherent in trying to split a large page mapping.
This is already far enough into "here be dragons" territory that no
sensible caller should ever hit it, and thus it really doesn't need
optimising. Although using tlb_flush_walk there may technically be
more heavyweight than needed, it does the job and saves everyone else
having to carry around useless baggage.
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Link: https://lore.kernel.org/r/9844ab0c5cb3da8b2f89c6c2da16941910702b41.1606324115.git.robin.murphy@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
Although handling a mapping request with no permissions is a
trivial no-op, defer the early return until after the size/range
checks so that we are consistent with other mapping requests.
Signed-off-by: Keqian Zhu <zhukeqian1@huawei.com>
Link: https://lore.kernel.org/r/20201207115758.9400-1-zhukeqian1@huawei.com
Signed-off-by: Will Deacon <will@kernel.org>
Now the ARM page tables are always allocated by GFP_ATOMIC parameter,
but the iommu_ops->map() function has been added a gfp_t parameter by
commit 781ca2de89 ("iommu: Add gfp parameter to iommu_ops::map"),
thus io_pgtable_ops->map() should use the gfp parameter passed from
iommu_ops->map() to allocate page pages, which can avoid wasting the
memory allocators atomic pools for some non-atomic contexts.
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/3093df4cb95497aaf713fca623ce4ecebb197c2e.1591930156.git.baolin.wang@linux.alibaba.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Although it's conceptually nice for the io_pgtable_cfg to provide a
standard VMSA TCR value, the reality is that no VMSA-compliant IOMMU
looks exactly like an Arm CPU, and they all have various other TCR
controls which io-pgtable can't be expected to understand. Thus since
there is an expectation that drivers will have to add to the given TCR
value anyway, let's strip it down to just the essentials that are
directly relevant to io-pgtable's inner workings - namely the various
sizes and the walk attributes.
Tested-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
[will: Add missing include of bitfield.h]
Signed-off-by: Will Deacon <will@kernel.org>
By VMSA rules, using Normal Non-Cacheable type with a shareability
attribute of anything other than Outer Shareable is liable to lead into
unpredictable territory:
| Overlaying the shareability attribute (B3-1377, ARM DDI 0406C.c)
|
| A memory region with a resultant memory type attribute of Normal, and
| a resultant cacheability attribute of Inner Non-cacheable, Outer
| Non-cacheable, must have a resultant shareability attribute of Outer
| Shareable, otherwise shareability is UNPREDICTABLE
Although the SMMU architectures seem to give some slightly stronger
guarantees of Non-Cacheable output types becoming implicitly Outer
Shareable in most cases, we may as well be explicit and not take any
chances. It's also weird that LPAE attribute handling is currently split
between prot_to_pte() and init_pte() given that it can all be statically
determined up-front. Thus, collect *all* the LPAE attributes into
prot_to_pte() in order to logically pick the shareability based on the
incoming IOMMU API prot value, and tweak the short-descriptor code to
stop setting TTBR0.NOS for Non-Cacheable walks.
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
TTBR1 values have so far been redundant since no users implement any
support for split address spaces. Crucially, though, one of the main
reasons for wanting to do so is to be able to manage each half entirely
independently, e.g. context-switching one set of mappings without
disturbing the other. Thus it seems unlikely that tying two tables
together in a single io_pgtable_cfg would ever be particularly desirable
or useful.
Streamline the configs to just a single conceptual TTBR value
representing the allocated table. This paves the way for future users to
support split address spaces by simply allocating a table and dealing
with the detailed TTBRn logistics themselves.
Tested-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
[will: Drop change to ttbr value]
Signed-off-by: Will Deacon <will@kernel.org>
The selftests run as an initcall, but the annotation of the various
callbacks and data seems to be somewhat arbitrary. Add it consistently
for everything related to the selftests.
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
MediaTek extend the arm v7s descriptor to support up to 34 bits PA where
the bit32 and bit33 are encoded in the bit9 and bit4 of the PTE
respectively. Meanwhile the iova still is 32bits.
Regarding whether the pagetable address could be over 4GB, the mt8183
support it while the previous mt8173 don't, thus keep it as is.
Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
In previous mt2712/mt8173, MediaTek extend the v7s to support 4GB dram.
But in the latest mt8183, We extend it to support the PA up to 34bit.
Then the "MTK_4GB" name is not so fit, This patch only change the quirk
name to "MTK_EXT".
Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Use ias/oas to check the valid iova/pa. Synchronize this checking with
io-pgtable-arm.c.
Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
With all the pieces in place, we can finally propagate the
iommu_iotlb_gather structure from the call to unmap() down to the IOMMU
drivers' implementation of ->tlb_add_page(). Currently everybody ignores
it, but the machinery is now there to defer invalidation.
Signed-off-by: Will Deacon <will@kernel.org>
Update the io-pgtable ->unmap() function to take an iommu_iotlb_gather
pointer as an argument, and update the callers as appropriate.
Signed-off-by: Will Deacon <will@kernel.org>
The ->tlb_add_flush() callback in the io-pgtable API now looks a bit
silly:
- It takes a size and a granule, which are always the same
- It takes a 'bool leaf', which is always true
- It only ever flushes a single page
With that in mind, replace it with an optional ->tlb_add_page() callback
that drops the useless parameters.
Signed-off-by: Will Deacon <will@kernel.org>
Now that all IOMMU drivers using the io-pgtable API implement the
->tlb_flush_walk() and ->tlb_flush_leaf() callbacks, we can use them in
the io-pgtable code instead of ->tlb_add_flush() immediately followed by
->tlb_sync().
Signed-off-by: Will Deacon <will@kernel.org>
In preparation for TLB flush gathering in the IOMMU API, rename the
iommu_gather_ops structure in io-pgtable to iommu_flush_ops, which
better describes its purpose and avoids the potential for confusion
between different levels of the API.
$ find linux/ -type f -name '*.[ch]' | xargs sed -i 's/gather_ops/flush_ops/g'
Signed-off-by: Will Deacon <will@kernel.org>
Commit b6b65ca20b ("iommu/io-pgtable-arm: Add support for non-strict
mode") added an unconditional call to io_pgtable_tlb_sync() immediately
after the case where we replace a block entry with a table entry during
an unmap() call. This is redundant, since the IOMMU API will call
iommu_tlb_sync() on this path and the patch in question mentions this:
| To save having to reason about it too much, make sure the invalidation
| in arm_lpae_split_blk_unmap() just performs its own unconditional sync
| to minimise the window in which we're technically violating the break-
| before-make requirement on a live mapping. This might work out redundant
| with an outer-level sync for strict unmaps, but we'll never be splitting
| blocks on a DMA fastpath anyway.
However, this sync gets in the way of deferred TLB invalidation for leaf
entries and is at best a questionable, unproven hack. Remove it.
Signed-off-by: Will Deacon <will@kernel.org>
Describe the memory related to page table walks as non-cacheable for
iommu instances that are not DMA coherent.
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
[will: Use cfg->coherent_walk, fix arm-v7s, ensure outer-shareable for NC]
Signed-off-by: Will Deacon <will@kernel.org>
IO_PGTABLE_QUIRK_NO_DMA is a bit of a misnomer, since it's really just
an indication of whether or not the page-table walker for the IOMMU is
coherent with the CPU caches. Since cache coherency is more than just a
quirk, replace the flag with its own field in the io_pgtable_cfg
structure.
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Will Deacon <will@kernel.org>
Based on 1 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation this program is
distributed in the hope that it will be useful but without any
warranty without even the implied warranty of merchantability or
fitness for a particular purpose see the gnu general public license
for more details you should have received a copy of the gnu general
public license along with this program if not see http www gnu org
licenses
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 503 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Enrico Weigelt <info@metux.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190602204653.811534538@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
IOMMUs using ARMv7 short-descriptor format require page tables (level 1
and 2) to be allocated within the first 4GB of RAM, even on 64-bit
systems.
For level 1/2 pages, ensure GFP_DMA32 is used if CONFIG_ZONE_DMA32 is
defined (e.g. on arm64 platforms).
For level 2 pages, allocate a slab cache in SLAB_CACHE_DMA32. Note that
we do not explicitly pass GFP_DMA[32] to kmem_cache_zalloc, as this is
not strictly necessary, and would cause a warning in mm/sl*b.c, as we
did not update GFP_SLAB_BUG_MASK.
Also, print an error when the physical address does not fit in
32-bit, to make debugging easier in the future.
Link: http://lkml.kernel.org/r/20181210011504.122604-3-drinkcat@chromium.org
Fixes: ad67f5a654 ("arm64: replace ZONE_DMA with ZONE_DMA32")
Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Hsin-Yi Wang <hsinyi@chromium.org>
Cc: Huaisheng Ye <yehs1@lenovo.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Sasha Levin <Alexander.Levin@microsoft.com>
Cc: Tomasz Figa <tfiga@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yingjoe Chen <yingjoe.chen@mediatek.com>
Cc: Yong Wu <yong.wu@mediatek.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
L1 tables are allocated with __get_dma_pages, and therefore already
ignored by kmemleak.
Without this, the kernel would print this error message on boot,
when the first L1 table is allocated:
[ 2.810533] kmemleak: Trying to color unknown object at 0xffffffd652388000 as Black
[ 2.818190] CPU: 5 PID: 39 Comm: kworker/5:0 Tainted: G S 4.19.16 #8
[ 2.831227] Workqueue: events deferred_probe_work_func
[ 2.836353] Call trace:
...
[ 2.852532] paint_ptr+0xa0/0xa8
[ 2.855750] kmemleak_ignore+0x38/0x6c
[ 2.859490] __arm_v7s_alloc_table+0x168/0x1f4
[ 2.863922] arm_v7s_alloc_pgtable+0x114/0x17c
[ 2.868354] alloc_io_pgtable_ops+0x3c/0x78
...
Fixes: e5fc9753b1 ("iommu/io-pgtable: Add ARMv7 short descriptor support")
Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Move io-pgtable.h to include/linux/ and export alloc_io_pgtable_ops
and free_io_pgtable_ops. This enables drivers outside drivers/iommu/ to
use the page table library. Specifically, some ARM Mali GPUs use the
ARM page table formats.
Cc: Will Deacon <will.deacon@arm.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: Rob Clark <robdclark@gmail.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: iommu@lists.linux-foundation.org
Cc: linux-mediatek@lists.infradead.org
Cc: linux-arm-msm@vger.kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
This reverts commit 82db33dc5e.
After the commit 29859aeb8a ("iommu/io-pgtable-arm-v7s: Abort
allocation when table address overflows the PTE"), v7s will return fail
if the page table allocation isn't expected. this PHYS_OFFSET check
is unnecessary now.
And this check may lead to fail. For example, If CONFIG_RANDOMIZE_BASE
is enabled, the "memstart_addr" will be updated randomly, then the
PHYS_OFFSET may be random.
Reported-by: CK Hu <ck.hu@mediatek.com>
Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
As for LPAE, it's simply a case of skipping the leaf invalidation for a
regular unmap, and ensuring that the one in split_blk_unmap() is paired
with an explicit sync ASAP rather than relying on one which might only
eventually happen way down the line.
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
When run on a 64-bit system in selftest, the v7s driver may obtain page
table with physical addresses larger than 32-bit. Level-2 tables are 1KB
and are are allocated with slab, which doesn't accept the GFP_DMA32
flag. Currently map() truncates the address written in the PTE, causing
iova_to_phys() or unmap() to access invalid memory. Kasan reports it as
a use-after-free. To avoid any nasty surprise, test if the physical
address fits in a PTE before returning a new table. 32-bit systems,
which are the main users of this page table format, shouldn't see any
difference.
Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
We can use for_each_set_bit() to simplify code slightly in the
ARM io-pgtable self tests while unmapping.
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Unmap returns a size_t all throughout the IOMMU framework.
Make io-pgtable match this convention.
Moreover, there isn't a need to have a signed int return type
as we return 0 in case of failures.
Signed-off-by: Vivek Gautam <vivek.gautam@codeaurora.org>
Acked-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Now that the core API issues its own post-unmap TLB sync call, push that
operation out from the io-pgtable-arm-v7s internals into the users. For
now, we leave the invalidation implicit in the unmap operation, since
none of the current users would benefit much from any change to that.
Note that the conversion of msm_iommu is implicit, since that apparently
has no specific TLB sync operation anyway.
CC: Yong Wu <yong.wu@mediatek.com>
CC: Rob Clark <robdclark@gmail.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Fix the commit 81b3c25218 ("iommu/io-pgtable: Introduce explicit
coherency"). If there is no IO_PGTABLE_QUIRK_NO_DMA, we should call
dma_sync_single_for_device for cache synchronization.
Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Fixes: 81b3c25218 ('iommu/io-pgtable: Introduce explicit coherency')
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
It may be an egregious error to attempt to use addresses outside the
range of the pagetable format, but that still doesn't mean we should
merrily wreak havoc by silently mapping/unmapping whatever truncated
portions of them might happen to correspond to real addresses.
Add some up-front checks to sanitise our inputs so that buggy callers
don't invite potential memory corruption.
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
When writing a new table entry, we must ensure that the contents of the
table is made visible to the SMMU page table walker before the updated
table entry itself.
This is currently achieved using wmb(), which expands to an expensive and
unnecessary DSB instruction. Ideally, we'd just use cmpxchg64_release when
writing the table entry, but this doesn't have memory ordering semantics
on !SMP systems.
Instead, use dma_wmb(), which emits DMB OSHST. Strictly speaking, this
does more than we require (since it targets the outer-shareable domain),
but it's likely to be significantly faster than the DSB approach.
Reported-by: Linu Cherian <linu.cherian@cavium.com>
Suggested-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Mirroring the LPAE implementation, rework the v7s code to be robust
against concurrent operations. The same two potential races exist, and
are solved in the same manner, with the fixed 2-level structure making
life ever so slightly simpler.
What complicates matters compared to LPAE, however, is large page
entries, since we can't update a block of 16 PTEs atomically, nor assume
available software bits to do clever things with. As most users are
never likely to do partial unmaps anyway (due to DMA API rules), it
doesn't seem unreasonable for this case to remain behind a serialising
lock; we just pull said lock down into the bowels of the implementation
so it's well out of the way of the normal call paths.
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Once we remove the serialising spinlock, a potential race opens up for
non-coherent IOMMUs whereby a caller of .map() can be sure that cache
maintenance has been performed on their new PTE, but will have no
guarantee that such maintenance for table entries above it has actually
completed (e.g. if another CPU took an interrupt immediately after
writing the table entry, but before initiating the DMA sync).
Handling this race safely will add some potentially non-trivial overhead
to installing a table entry, which we would much rather avoid on
coherent systems where it will be unnecessary, and where we are stirivng
to minimise latency by removing the locking in the first place.
To that end, let's introduce an explicit notion of cache-coherency to
io-pgtable, such that we will be able to avoid penalising IOMMUs which
know enough to know when they are coherent.
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Whilst the short-descriptor format's split_blk_unmap implementation has
no need to be recursive, it followed the pattern of the LPAE version
anyway for the sake of consistency. With the latter now reworked for
both efficiency and future scalability improvements, tweak the former
similarly, not least to make it less obtuse.
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
