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[ Upstream commitdcd9c76e5a] When enabling IOMMU support, the following issue becomes visible in the AEAD zero-length case. Even though the output sequence length is set to zero, the crypto engine tries to prefetch 4 S/G table entries (since SGF bit is set in SEQ OUT PTR command - which is either generated in SW in case of caam/jr or in HW in case of caam/qi, caam/qi2). The DMA read operation will trigger an IOMMU fault since the address in the SEQ OUT PTR is "dummy" (set to zero / not obtained via DMA API mapping). 1. In case of caam/jr, avoid the IOMMU fault by clearing the SGF bit in SEQ OUT PTR command. 2. In case of caam/qi - setting address, bpid, length to zero for output entry in the compound frame has a special meaning (cf. CAAM RM): "Output frame = Unspecified, Input address = Y. A unspecified frame is indicated by an unused SGT entry (an entry in which the Address, Length, and BPID fields are all zero). SEC obtains output buffers from BMan as prescribed by the preheader." Since no output buffers are needed, modify the preheader by setting (ABS = 1, ADDBUF = 0): -"ABS = 1 means obtain the number of buffers in ADDBUF (0 or 1) from the pool POOL ID" -ADDBUF: "If ABS is set, ADD BUF specifies whether to allocate a buffer or not" 3. In case of caam/qi2, since engine: -does not support FLE[FMT]=2'b11 ("unused" entry) mentioned in DPAA2 RM -requires output entry to be present, even if not used the solution chosen is to leave output frame list entry zeroized. Fixes:763069ba49("crypto: caam - handle zero-length AEAD output") Signed-off-by: Horia Geantă <horia.geanta@nxp.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.