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.

Fixes: 4bf97069239b ("riscv: Add ghostwrite vulnerability")
Signed-off-by: Zongmin Zhou <zhouzongmin@kylinos.cn>
Link: https://patch.msgid.link/20260917074843.52716-1-min_halo@163.com
Cc: stable@vger.kernel.org
Signed-off-by: Paul Walmsley <pjw@kernel.org>

0 files changed, 0 insertions, 0 deletions