riscv: errata: select RISCV_ALTERNATIVE_EARLY for THEAD GHOSTWRITE

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No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

In the Linux kernel, the following vulnerability has been resolved: riscv: errata: select RISCV_ALTERNATIVE_EARLY for THEAD GHOSTWRITE errata_probe_ghostwrite() only marks the CPU as vulnerable when it is called at the RISCV_ALTERNATIVES_EARLY_BOOT stage, and the mitigation in ghostwrite_enable_mitigation() only takes effect if the vulnerable state was recorded before the boot alternatives are patched. The early boot stage is only executed when CONFIG_RISCV_ALTERNATIVE_EARLY is enabled, which currently is only selected by ERRATA_THEAD_MAE. In a kernel built with ERRATA_THEAD_GHOSTWRITE=y but ERRATA_THEAD_MAE=n, the early alternatives never run, so ghostwrite_state is never set to VULNERABLE: ghostwrite_enable_mitigation() returns false, xtheadvector remains enabled, and sysfs reports "Not affected" on a vulnerable T-Head C9xx CPU. Select RISCV_ALTERNATIVE_EARLY from ERRATA_THEAD_GHOSTWRITE so that the vulnerability is detected in the early boot stage and the default mitigation is applied.

Source published

23 Oct 2026 12:20:53 UTC

Source modified

24 Oct 2026 14:10:04 UTC

Observed here

24 Oct 2026 16:17:04 UTC

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CVSS 3.1 · 7.0 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H