Use a simple logical shift and increment to calculate the number of slots
taken by the DMA segment boundary.
At least GCC-13 is not able to optimize the expression, producing this
horrible assembly code on x86:
cmpq $-1, %rcx
je .L364
addq $2048, %rcx
shrq $11, %rcx
movq %rcx, %r13
.L331:
// rest of the function here...
// after function epilogue and return:
.L364:
movabsq $9007199254740992, %r13
jmp .L331
After the optimization, the code looks more reasonable:
shrq $11, %r11
leaq 1(%r11), %rbx
Signed-off-by: Petr Tesarik <petr.tesarik.ext@huawei.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Move the comment down in front of the loop that actually sets the list
member of struct io_tlb_slot to zero.
Fixes: 26a7e09478 ("swiotlb: refactor swiotlb_tbl_map_single")
Signed-off-by: Petr Tesarik <petr.tesarik.ext@huawei.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Skip searching the software IO TLB if a device has never used it, making
sure these devices are not affected by the introduction of multiple IO TLB
memory pools.
Additional memory barrier is required to ensure that the new value of the
flag is visible to other CPUs after mapping a new bounce buffer. For
efficiency, the flag check should be inlined, and then the memory barrier
must be moved to is_swiotlb_buffer(). However, it can replace the existing
barrier in swiotlb_find_pool(), because all callers use is_swiotlb_buffer()
first to verify that the buffer address belongs to the software IO TLB.
Signed-off-by: Petr Tesarik <petr.tesarik.ext@huawei.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
When swiotlb_find_slots() cannot find suitable slots, schedule the
allocation of a new memory pool. It is not possible to allocate the pool
immediately, because this code may run in interrupt context, which is not
suitable for large memory allocations. This means that the memory pool will
be available too late for the currently requested mapping, but the stress
on the software IO TLB allocator is likely to continue, and subsequent
allocations will benefit from the additional pool eventually.
Keep all memory pools for an allocator in an RCU list to avoid locking on
the read side. For modifications, add a new spinlock to struct io_tlb_mem.
The spinlock also protects updates to the total number of slabs (nslabs in
struct io_tlb_mem), but not reads of the value. Readers may therefore
encounter a stale value, but this is not an issue:
- swiotlb_tbl_map_single() and is_swiotlb_active() only check for non-zero
value. This is ensured by the existence of the default memory pool,
allocated at boot.
- The exact value is used only for non-critical purposes (debugfs, kernel
messages).
Signed-off-by: Petr Tesarik <petr.tesarik.ext@huawei.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
The value returned by default_swiotlb_limit() should be constant, because
it is used to decide whether DMA can be used. To allow allocating memory
pools on the fly, use the maximum possible physical address rather than the
highest address used by the default pool.
For swiotlb_init_remap(), this is either an arch-specific limit used by
memblock_alloc_low(), or the highest directly mapped physical address if
the initialization flags include SWIOTLB_ANY. For swiotlb_init_late(), the
highest address is determined by the GFP flags.
Signed-off-by: Petr Tesarik <petr.tesarik.ext@huawei.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Try to allocate a transient memory pool if no suitable slots can be found
and the respective SWIOTLB is allowed to grow. The transient pool is just
enough big for this one bounce buffer. It is inserted into a per-device
list of transient memory pools, and it is freed again when the bounce
buffer is unmapped.
Transient memory pools are kept in an RCU list. A memory barrier is
required after adding a new entry, because any address within a transient
buffer must be immediately recognized as belonging to the SWIOTLB, even if
it is passed to another CPU.
Deletion does not require any synchronization beyond RCU ordering
guarantees. After a buffer is unmapped, its physical addresses may no
longer be passed to the DMA API, so the memory range of the corresponding
stale entry in the RCU list never matches. If the memory range gets
allocated again, then it happens only after a RCU quiescent state.
Since bounce buffers can now be allocated from different pools, add a
parameter to swiotlb_alloc_pool() to let the caller know which memory pool
is used. Add swiotlb_find_pool() to find the memory pool corresponding to
an address. This function is now also used by is_swiotlb_buffer(), because
a simple boundary check is no longer sufficient.
The logic in swiotlb_alloc_tlb() is taken from __dma_direct_alloc_pages(),
simplified and enhanced to use coherent memory pools if needed.
Note that this is not the most efficient way to provide a bounce buffer,
but when a DMA buffer can't be mapped, something may (and will) actually
break. At that point it is better to make an allocation, even if it may be
an expensive operation.
Signed-off-by: Petr Tesarik <petr.tesarik.ext@huawei.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Add a config option (CONFIG_SWIOTLB_DYNAMIC) to enable or disable dynamic
allocation of additional bounce buffers.
If this option is set, mark the default SWIOTLB as able to grow and
restricted DMA pools as unable.
However, if the address of the default memory pool is explicitly queried,
make the default SWIOTLB also unable to grow. This is currently used to set
up PCI BAR movable regions on some Octeon MIPS boards which may not be able
to use a SWIOTLB pool elsewhere in physical memory. See octeon_pci_setup()
for more details.
If a remap function is specified, it must be also called on any dynamically
allocated pools, but there are some issues:
- The remap function may block, so it should not be called from an atomic
context.
- There is no corresponding unremap() function if the memory pool is
freed.
- The only in-tree implementation (xen_swiotlb_fixup) requires that the
number of slots in the memory pool is a multiple of SWIOTLB_SEGSIZE.
Keep it simple for now and disable growing the SWIOTLB if a remap function
was specified.
Signed-off-by: Petr Tesarik <petr.tesarik.ext@huawei.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Carve out memory pool specific fields from struct io_tlb_mem. The original
struct now contains shared data for the whole allocator, while the new
struct io_tlb_pool contains data that is specific to one memory pool of
(potentially) many.
Signed-off-by: Petr Tesarik <petr.tesarik.ext@huawei.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Add some kernel-doc comments and move the existing documentation of struct
io_tlb_slot to its correct location. The latter was forgotten in commit
942a8186eb ("swiotlb: move struct io_tlb_slot to swiotlb.c").
Use the opportunity to give swiotlb_do_find_slots() a more descriptive name
and make it clear how it differs from swiotlb_find_slots().
Signed-off-by: Petr Tesarik <petr.tesarik.ext@huawei.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
SWIOTLB implementation details should not be exposed to the rest of the
kernel. This will allow to make changes to the implementation without
modifying non-swiotlb code.
To avoid breaking existing users, provide helper functions for the few
required fields.
As a bonus, using a helper function to initialize struct device allows to
get rid of an #ifdef in driver core.
Signed-off-by: Petr Tesarik <petr.tesarik.ext@huawei.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
If swiotlb is allocated, immediately return 0, so callers do not have to
check io_tlb_default_mem.nslabs explicitly.
Signed-off-by: Petr Tesarik <petr.tesarik.ext@huawei.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Drivers have no business looking at dma-mapping or swiotlb internals.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
Although the desired size of the SWIOTLB memory pool is increased in
swiotlb_adjust_nareas() to match the number of areas, the actual allocation
may be smaller, which may require reducing the number of areas.
For example, Xen uses swiotlb_init_late(), which in turn uses the page
allocator. On x86, page size is 4 KiB and MAX_ORDER is 10 (1024 pages),
resulting in a maximum memory pool size of 4 MiB. This corresponds to 2048
slots of 2 KiB each. The minimum area size is 128 (IO_TLB_SEGSIZE),
allowing at most 2048 / 128 = 16 areas.
If num_possible_cpus() is greater than the maximum number of areas, areas
are smaller than IO_TLB_SEGSIZE and contiguous groups of free slots will
span multiple areas. When allocating and freeing slots, only one area will
be properly locked, causing race conditions on the unlocked slots and
ultimately data corruption, kernel hangs and crashes.
Fixes: 20347fca71 ("swiotlb: split up the global swiotlb lock")
Signed-off-by: Petr Tesarik <petr.tesarik.ext@huawei.com>
Reviewed-by: Roberto Sassu <roberto.sassu@huawei.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
The number of areas defaults to the number of possible CPUs. However, the
total number of slots may have to be increased after adjusting the number
of areas. Consequently, the number of areas must be determined before
allocating the memory pool. This is even explained with a comment in
swiotlb_init_remap(), but swiotlb_init_late() adjusts the number of areas
after slots are already allocated. The areas may end up being smaller than
IO_TLB_SEGSIZE, which breaks per-area locking.
While fixing swiotlb_init_late(), move all relevant comments before the
definition of swiotlb_adjust_nareas() and convert them to kernel-doc.
Fixes: 20347fca71 ("swiotlb: split up the global swiotlb lock")
Signed-off-by: Petr Tesarik <petr.tesarik.ext@huawei.com>
Reviewed-by: Roberto Sassu <roberto.sassu@huawei.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
If DEBUG_FS is enabled, the cost of keeping an exact number of total
used slabs is already paid. In this case, there is no reason to use an
inexact number for statistics and kernel messages.
Signed-off-by: Petr Tesarik <petr.tesarik.ext@huawei.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
- fix a PageHighMem check in dma-coherent initialization (Doug Berger)
- clean up the coherency defaul initialiation (Jiaxun Yang)
- add cacheline to user/kernel dma-debug space dump messages
(Desnes Nunes, Geert Uytterhoeve)
- swiotlb statistics improvements (Michael Kelley)
- misc cleanups (Petr Tesarik)
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Merge tag 'dma-mapping-6.4-2023-04-28' of git://git.infradead.org/users/hch/dma-mapping
Pull dma-mapping updates from Christoph Hellwig:
- fix a PageHighMem check in dma-coherent initialization (Doug Berger)
- clean up the coherency defaul initialiation (Jiaxun Yang)
- add cacheline to user/kernel dma-debug space dump messages (Desnes
Nunes, Geert Uytterhoeve)
- swiotlb statistics improvements (Michael Kelley)
- misc cleanups (Petr Tesarik)
* tag 'dma-mapping-6.4-2023-04-28' of git://git.infradead.org/users/hch/dma-mapping:
swiotlb: Omit total_used and used_hiwater if !CONFIG_DEBUG_FS
swiotlb: track and report io_tlb_used high water marks in debugfs
swiotlb: fix debugfs reporting of reserved memory pools
swiotlb: relocate PageHighMem test away from rmem_swiotlb_setup
of: address: always use dma_default_coherent for default coherency
dma-mapping: provide CONFIG_ARCH_DMA_DEFAULT_COHERENT
dma-mapping: provide a fallback dma_default_coherent
dma-debug: Use %pa to format phys_addr_t
dma-debug: add cacheline to user/kernel space dump messages
dma-debug: small dma_debug_entry's comment and variable name updates
dma-direct: cleanup parameters to dma_direct_optimal_gfp_mask
The tracking of used_hiwater adds an atomic operation to the hot
path. This is acceptable only when debugging the kernel. To make
sure that the fields can never be used by mistake, do not even
include them in struct io_tlb_mem if CONFIG_DEBUG_FS is not set.
The build fails after doing that. To fix it, it is necessary to
remove all code specific to debugfs and instead provide a stub
implementation of swiotlb_create_debugfs_files(). As a bonus, this
change allows to remove one __maybe_unused attribute.
Signed-off-by: Petr Tesarik <petr.tesarik.ext@huawei.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
With changes to how Hyper-V guest VMs flip memory between private
(encrypted) and shared (decrypted), creating a second kernel virtual
mapping for shared memory is no longer necessary. Everything needed
for the transition to shared is handled by set_memory_decrypted().
As such, remove swiotlb_unencrypted_base and the associated
code.
Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Acked-by: Christoph Hellwig <hch@lst.de>
Acked-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/1679838727-87310-8-git-send-email-mikelley@microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
swiotlb currently reports the total number of slabs and the instantaneous
in-use slabs in debugfs. But with increased usage of swiotlb for all I/O
in Confidential Computing (coco) VMs, it has become difficult to know
how much memory to allocate for swiotlb bounce buffers, either via the
automatic algorithm in the kernel or by specifying a value on the
kernel boot line. The current automatic algorithm generously allocates
swiotlb bounce buffer memory, and may be wasting significant memory in
many use cases.
To support better understanding of swiotlb usage, add tracking of the
the high water mark for usage of the default swiotlb bounce buffer memory
pool and any reserved memory pools. Report these high water marks in
debugfs along with the other swiotlb pool metrics. Allow the high water
marks to be reset to zero at runtime by writing to them.
Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
For io_tlb_nslabs, the debugfs code reports the correct value for a
specific reserved memory pool. But for io_tlb_used, the value reported
is always for the default pool, not the specific reserved pool. Fix this.
Fixes: 5c850d3188 ("swiotlb: fix passing local variable to debugfs_create_ulong()")
Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
The reservedmem_of_init_fn's are invoked very early at boot before the
memory zones have even been defined. This makes it inappropriate to test
whether the page corresponding to a PFN is in ZONE_HIGHMEM from within
one.
Removing the check allows an ARM 32-bit kernel with SPARSEMEM enabled to
boot properly since otherwise we would be de-referencing an
uninitialized sparsemem map to perform pfn_to_page() check.
The arm64 architecture happens to work (and also has no high memory) but
other 32-bit architectures could also be having similar issues.
While it would be nice to provide early feedback about a reserved DMA
pool residing in highmem, it is not possible to do that until the first
time we try to use it, which is where the check is moved to.
Fixes: 0b84e4f8b7 ("swiotlb: Add restricted DMA pool initialization")
Signed-off-by: Doug Berger <opendmb@gmail.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
The alignment mask in swiotlb_do_find_slots() masks off the high
bits which are not relevant for the alignment, so multiple
requirements are combined with a bitwise OR rather than AND.
In plain English, the stricter the alignment, the more bits must
be set in iotlb_align_mask.
Confusion may arise from the fact that the same variable is also
used to mask off the offset within a swiotlb slot, which is
achieved with a bitwise AND.
Fixes: 0eee5ae102 ("swiotlb: fix slot alignment checks")
Reported-by: Dexuan Cui <decui@microsoft.com>
Link: https://lore.kernel.org/all/CAA42JLa1y9jJ7BgQvXeUYQh-K2mDNHd2BYZ4iZUz33r5zY7oAQ@mail.gmail.com/
Reported-by: Kelsey Steele <kelseysteele@linux.microsoft.com>
Link: https://lore.kernel.org/all/20230405003549.GA21326@linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net/
Signed-off-by: Petr Tesarik <petr.tesarik.ext@huawei.com>
Tested-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Explicit alignment and page alignment are used only to calculate
the stride, not when checking actual slot physical address.
Originally, only page alignment was implemented, and that worked,
because the whole SWIOTLB is allocated on a page boundary, so
aligning the start index was sufficient to ensure a page-aligned
slot.
When commit 1f221a0d0d ("swiotlb: respect min_align_mask") added
support for min_align_mask, the index could be incremented in the
search loop, potentially finding an unaligned slot if minimum device
alignment is between IO_TLB_SIZE and PAGE_SIZE. The bug could go
unnoticed, because the slot size is 2 KiB, and the most common page
size is 4 KiB, so there is no alignment value in between.
IIUC the intention has been to find a slot that conforms to all
alignment constraints: device minimum alignment, an explicit
alignment (given as function parameter) and optionally page
alignment (if allocation size is >= PAGE_SIZE). The most
restrictive mask can be trivially computed with logical AND. The
rest can stay.
Fixes: 1f221a0d0d ("swiotlb: respect min_align_mask")
Fixes: e81e99bacc ("swiotlb: Support aligned swiotlb buffers")
Signed-off-by: Petr Tesarik <petr.tesarik.ext@huawei.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
No functional change, just use an existing helper.
Signed-off-by: Petr Tesarik <petr.tesarik.ext@huawei.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
In general, if swiotlb is sufficient, the logic of index =
wrap_area_index(mem, index + 1) is fine, it will quickly take a slot and
release the area->lock; But if swiotlb is insufficient and the device
has min_align_mask requirements, such as NVME, we may not be able to
satisfy index == wrap and exit the loop properly. In this case, other
kernel threads will not be able to acquire the area->lock and release
the slot, resulting in a deadlock.
The current implementation of wrap_area_index does not involve a modulo
operation, so adjusting the wrap to ensure the loop ends is not trivial.
Introduce a new variable to record the number of loops and exit the loop
after completing the traversal.
Backtraces:
Other CPUs are waiting this core to exit the swiotlb_do_find_slots
loop.
[10199.924391] RIP: 0010:swiotlb_do_find_slots+0x1fe/0x3e0
[10199.924403] Call Trace:
[10199.924404] <TASK>
[10199.924405] swiotlb_tbl_map_single+0xec/0x1f0
[10199.924407] swiotlb_map+0x5c/0x260
[10199.924409] ? nvme_pci_setup_prps+0x1ed/0x340
[10199.924411] dma_direct_map_page+0x12e/0x1c0
[10199.924413] nvme_map_data+0x304/0x370
[10199.924415] nvme_prep_rq.part.0+0x31/0x120
[10199.924417] nvme_queue_rq+0x77/0x1f0
...
[ 9639.596311] NMI backtrace for cpu 48
[ 9639.596336] Call Trace:
[ 9639.596337]
[ 9639.596338] _raw_spin_lock_irqsave+0x37/0x40
[ 9639.596341] swiotlb_do_find_slots+0xef/0x3e0
[ 9639.596344] swiotlb_tbl_map_single+0xec/0x1f0
[ 9639.596347] swiotlb_map+0x5c/0x260
[ 9639.596349] dma_direct_map_sg+0x7a/0x280
[ 9639.596352] __dma_map_sg_attrs+0x30/0x70
[ 9639.596355] dma_map_sgtable+0x1d/0x30
[ 9639.596356] nvme_map_data+0xce/0x370
...
[ 9639.595665] NMI backtrace for cpu 50
[ 9639.595682] Call Trace:
[ 9639.595682]
[ 9639.595683] _raw_spin_lock_irqsave+0x37/0x40
[ 9639.595686] swiotlb_release_slots.isra.0+0x86/0x180
[ 9639.595688] dma_direct_unmap_sg+0xcf/0x1a0
[ 9639.595690] nvme_unmap_data.part.0+0x43/0xc0
Fixes: 1f221a0d0d ("swiotlb: respect min_align_mask")
Signed-off-by: GuoRui.Yu <GuoRui.Yu@linux.alibaba.com>
Signed-off-by: Xiaokang Hu <xiaokang.hxk@alibaba-inc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
swiotlb_memblock_alloc() calls memblock_alloc(), which calls
(__init) memblock_alloc_try_nid(). However, swiotlb_membloc_alloc()
can be marked as __init since it is only called by swiotlb_init_remap(),
which is already marked as __init. This prevents a modpost build
warning/error:
WARNING: modpost: vmlinux.o: section mismatch in reference: swiotlb_memblock_alloc (section: .text) -> memblock_alloc_try_nid (section: .init.text)
WARNING: modpost: vmlinux.o: section mismatch in reference: swiotlb_memblock_alloc (section: .text) -> memblock_alloc_try_nid (section: .init.text)
This fixes the build warning/error seen on ARM64, PPC64, S390, i386,
and x86_64.
Fixes: 8d58aa4849 ("swiotlb: reduce the swiotlb buffer size on allocation failure")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Alexey Kardashevskiy <aik@amd.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: iommu@lists.linux.dev
Cc: Mike Rapoport <rppt@kernel.org>
Cc: linux-mm@kvack.org
Signed-off-by: Christoph Hellwig <hch@lst.de>
swiotlb_max_segment has always been a bogus API, so remove it now that
the remaining callers are gone.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
At the moment the AMD encrypted platform reserves 6% of RAM for SWIOTLB
or 1GB, whichever is less. However it is possible that there is no block
big enough in the low memory which make SWIOTLB allocation fail and
the kernel continues without DMA. In such case a VM hangs on DMA.
This moves alloc+remap to a helper and calls it from a loop where
the size is halved on each iteration.
This updates default_nslabs on successful allocation which looks like
an oversight as not doing so should have broken callers of
swiotlb_size_or_default().
Signed-off-by: Alexey Kardashevskiy <aik@amd.com>
Reviewed-by: Pankaj Gupta <pankaj.gupta@amd.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
The panics in swiotlb are relics of a bygone era, some of them
inadvertently inherited from a memblock refactor, and all of them
unnecessary since they are in places that may also fail gracefully
anyway.
Convert the panics in swiotlb_init_remap() into non-fatal warnings
more consistent with the other bail-out paths there and in
swiotlb_init_late() (but don't bother trying to roll anything back,
since if anything does actually fail that early, the aim is merely to
keep going as far as possible to get more diagnostic information out
of the inevitably-dying kernel). It's not for SWIOTLB to decide that the
system is terminally compromised just because there *might* turn out to
be one or more 32-bit devices that might want to make streaming DMA
mappings, especially since we already handle the no-buffer case later
if it turns out someone did want it.
Similarly though, downgrade that panic in swiotlb_tbl_map_single(),
since even if we do get to that point it's an overly extreme reaction.
It makes little difference to the DMA API caller whether a mapping fails
because the buffer is full or because there is no buffer, and once again
it's not for SWIOTLB to presume that any particular DMA mapping is so
fundamental to the operation of the system that it must be terminal if
it could never succeed. Even if the caller handles failure by futilely
retrying forever, a single stuck thread is considerably less impactful
to the user than a needless panic.
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
The use of kmap_atomic() is being deprecated in favor of
kmap_local_page(), which can also be used in atomic context (including
interrupts).
Replace kmap_atomic() with kmap_local_page(). Instead of open coding
mapping, memcpy(), and un-mapping, use the memcpy_{from,to}_page() helper.
Suggested-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
The second operand passed to slot_addr() is declared as int or unsigned int
in all call sites. The left-shift to get the offset of a slot can overflow
if swiotlb size is larger than 4G.
Convert the macro to an inline function and declare the second argument as
phys_addr_t to avoid the potential overflow.
Fixes: 26a7e09478 ("swiotlb: refactor swiotlb_tbl_map_single")
Signed-off-by: Chao Gao <chao.gao@intel.com>
Reviewed-by: Dongli Zhang <dongli.zhang@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Debugfs node will be run-timely checked and so local variable
should be not passed to debugfs_create_ulong(). Fix it via
debugfs_create_file() to create io_tlb_used node and calculate
used io tlb number with fops_io_tlb_used attribute.
Fixes: 20347fca71 ("swiotlb: split up the global swiotlb lock")
Signed-off-by: Tianyu Lan <tiala@microsoft.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
- Fix the used field of struct io_tlb_area wasn't initialized
- Set area number to be 0 if input area number parameter is 0
- Use array_size() to calculate io_tlb_area array size
- Make parameters of swiotlb_do_find_slots() more reasonable
Fixes: 26ffb91fa5e0 ("swiotlb: split up the global swiotlb lock")
Signed-off-by: Tianyu Lan <tiala@microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Free slots tracking assumes that slots in a segment can be allocated to
fulfill a request. This implies that slots in a segment should belong to
the same area. Although the possibility of a violation is low, it is better
to explicitly enforce segments won't span multiple areas by adjusting the
number of slabs when configuring areas.
Signed-off-by: Chao Gao <chao.gao@intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
default_nslabs are rounded up in two cases with exactly same comments.
Add a simple wrapper to reduce duplicate code/comments. It is preparatory
to adding more logics into the round-up.
No functional change intended.
Signed-off-by: Chao Gao <chao.gao@intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Commit 20347fca71 ("swiotlb: split up the global swiotlb lock") splits
io_tlb_mem into multiple areas. Each area has its own lock and index. The
global ones are not used so remove them.
Signed-off-by: Chao Gao <chao.gao@intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Don't dereference "mem" after it has been freed. Flip the
two kfree()s around to address this bug.
Fixes: 26ffb91fa5e0 ("swiotlb: split up the global swiotlb lock")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Traditionally swiotlb was not performance critical because it was only
used for slow devices. But in some setups, like TDX/SEV confidential
guests, all IO has to go through swiotlb. Currently swiotlb only has a
single lock. Under high IO load with multiple CPUs this can lead to
significat lock contention on the swiotlb lock.
This patch splits the swiotlb bounce buffer pool into individual areas
which have their own lock. Each CPU tries to allocate in its own area
first. Only if that fails does it search other areas. On freeing the
allocation is freed into the area where the memory was originally
allocated from.
Area number can be set via swiotlb kernel parameter and is default
to be possible cpu number. If possible cpu number is not power of
2, area number will be round up to the next power of 2.
This idea from Andi Kleen patch(https://github.com/intel/tdx/commit/
4529b5784c141782c72ec9bd9a92df2b68cb7d45).
Based-on-idea-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
In the failure case of trying to use a buffer which we'd previously
failed to allocate, the "!mem" condition is no longer sufficient since
io_tlb_default_mem became static and assigned by default. Update the
condition to work as intended per the rest of that conversion.
Fixes: 463e862ac6 ("swiotlb: Convert io_default_tlb_mem to static allocation")
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Panic on purpose if nslabs is too small, in order to sync with the remap
retry logic.
In addition, print the number of bytes for tlb alloc failure.
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Both swiotlb_init_remap() and swiotlb_init() have return type void.
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
The swiotlb_init refactor messed up assigning ->force_bounce by doing
it in different places based on what caused the setting of the flag.
Fix this by passing the SWIOTLB_* flags to swiotlb_init_io_tlb_mem
and just setting it there.
Fixes: c6af2aa9ff ("swiotlb: make the swiotlb_init interface more useful")
Reported-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Nathan Chancellor <nathan@kernel.org>
swiotlb_find_slots() skips slots according to io tlb aligned mask
calculated from min aligned mask and original physical address
offset. This affects max mapping size. The mapping size can't
achieve the IO_TLB_SEGSIZE * IO_TLB_SIZE when original offset is
non-zero. This will cause system boot up failure in Hyper-V
Isolation VM where swiotlb force is enabled. Scsi layer use return
value of dma_max_mapping_size() to set max segment size and it
finally calls swiotlb_max_mapping_size(). Hyper-V storage driver
sets min align mask to 4k - 1. Scsi layer may pass 256k length of
request buffer with 0~4k offset and Hyper-V storage driver can't
get swiotlb bounce buffer via DMA API. Swiotlb_find_slots() can't
find 256k length bounce buffer with offset. Make swiotlb_max_mapping
_size() take min align mask into account.
Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
nslabs can shrink when allocations or the remap don't succeed, so make
sure to use it for all sizing. For that remove the bytes value that
can get stale and replace it with local calculations and a boolean to
indicate if the originally requested size could not be allocated.
Fixes: 6424e31b1c ("swiotlb: remove swiotlb_init_with_tbl and swiotlb_init_late_with_tbl")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
default_nslabs should only be used to initialize nslabs, after that we
need to use the local variable that can shrink when allocations or the
remap don't succeed.
Fixes: 6424e31b1c ("swiotlb: remove swiotlb_init_with_tbl and swiotlb_init_late_with_tbl")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
For historical reasons the switlb code paniced when the metadata could
not be allocated, but just printed a warning when the actual main
swiotlb buffer could not be allocated. Restore this somewhat unexpected
behavior as changing it caused a boot failure on the Microchip RISC-V
PolarFire SoC Icicle kit.
Fixes: 6424e31b1c ("swiotlb: remove swiotlb_init_with_tbl and swiotlb_init_late_with_tbl")
Reported-by: Conor Dooley <Conor.Dooley@microchip.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Tested-by: Conor Dooley <Conor.Dooley@microchip.com>
No users left.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
