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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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004cc08675
Pull x86 tsx fixes from Thomas Gleixner: "This update provides kernel side handling for the TSX erratum of Intel Skylake (and later) CPUs. On these CPUs Intel Transactional Synchronization Extensions (TSX) functions can result in unpredictable system behavior under certain circumstances. The issue is mitigated with an microcode update which utilizes Performance Monitoring Counter (PMC) 3 when TSX functions are in use. This mitigation is enabled unconditionally by the updated microcode. As a consequence the usage of TSX functions can cause corrupted performance monitoring results for events which utilize PMC3. The corruption is silent on kernels which have no update for this issue. This update makes the kernel aware of the PMC3 utilization by the microcode: The microcode offers a possibility to enforce TSX abort which prevents the malfunction and frees up PMC3. The enforced TSX abort requires the TSX using application to have a software fallback path implemented; abort handlers which solely retry the transaction will fail over and over. The enforced TSX abort request is issued by the kernel when: - enforced TSX abort is enabled (PMU attribute) - A performance monitoring request needs PMC3 When PMC3 is not longer used by the kernel the TSX force abort request is cleared. The enforced TSX abort mechanism is enabled by default and can be controlled by the administrator via the new PMU attribute 'allow_tsx_force_abort'. This attribute is only visible when updated microcode is detected on affected systems. Writing '0' disables the enforced TSX abort mechanism, '1' enables it. As a result of disabling the enforced TSX abort mechanism, PMC3 is permanentely unavailable for performance monitoring which can cause performance monitoring requests to fail or switch to multiplexing mode" * branch 'x86-tsx-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: perf/x86/intel: Implement support for TSX Force Abort x86: Add TSX Force Abort CPUID/MSR perf/x86/intel: Generalize dynamic constraint creation perf/x86/intel: Make cpuc allocations consistent |
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