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The goal of erratum #27704 workaround was to make sure that ASIDs and VMIDs are unique across all SMMU instances on affected Cavium systems. Currently, the workaround code partitions ASIDs and VMIDs by increasing global cavium_smmu_context_count which in turn becomes the base ASID and VMID value for the given SMMU instance upon the context bank initialization. For systems with multiple SMMU instances this approach implies the risk of crossing 8-bit ASID, like for 1-socket CN88xx capable of 4 SMMUv2, 128 context banks each: SMMU_0 (0-127 ASID RANGE) SMMU_1 (127-255 ASID RANGE) SMMU_2 (256-383 ASID RANGE) <--- crossing 8-bit ASID SMMU_3 (384-511 ASID RANGE) <--- crossing 8-bit ASID Since now we use 8-bit ASID (SMMU_CBn_TCR2.AS = 0) we effectively misconfigure ASID[15:8] bits of SMMU_CBn_TTBRm register for SMMU_2/3. Moreover, we still assume non-zero ASID[15:8] bits upon context invalidation. In the end, except SMMU_0/1 devices all other devices under other SMMUs will fail on guest power off/on. Since we try to invalidate TLB with 16-bit ASID but we actually have 8-bit zero padded 16-bit entry. This patch adds 16-bit ASID support for stage-1 AArch64 contexts so that we use ASIDs consistently for all SMMU instances. Signed-off-by: Tomasz Nowicki <tn@semihalf.com> Reviewed-by: Robin Murphy <robin.murphy@arm.com> Reviewed-by: Tirumalesh Chalamarla <Tirumalesh.Chalamarla@cavium.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.