From cac642c12a805ae7565a263b59fb94ad19e81952 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Thu, 8 Apr 2021 14:10:08 +0100 Subject: arm64: cpufeature: Allow early filtering of feature override Some CPUs are broken enough that some overrides need to be rejected at the earliest opportunity. In some cases, that's right at cpu feature override time. Provide the necessary infrastructure to filter out overrides, and to report such filtered out overrides to the core cpufeature code. Acked-by: Will Deacon Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20210408131010.1109027-2-maz@kernel.org Signed-off-by: Catalin Marinas --- arch/arm64/kernel/idreg-override.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) (limited to 'arch/arm64/kernel/idreg-override.c') diff --git a/arch/arm64/kernel/idreg-override.c b/arch/arm64/kernel/idreg-override.c index 83f1c4b92095..be92fcd319a1 100644 --- a/arch/arm64/kernel/idreg-override.c +++ b/arch/arm64/kernel/idreg-override.c @@ -25,6 +25,7 @@ struct ftr_set_desc { struct { char name[FTR_DESC_FIELD_LEN]; u8 shift; + bool (*filter)(u64 val); } fields[]; }; @@ -124,6 +125,18 @@ static void __init match_options(const char *cmdline) if (find_field(cmdline, regs[i], f, &v)) continue; + /* + * If an override gets filtered out, advertise + * it by setting the value to 0xf, but + * clearing the mask... Yes, this is fragile. + */ + if (regs[i]->fields[f].filter && + !regs[i]->fields[f].filter(v)) { + regs[i]->override->val |= mask; + regs[i]->override->mask &= ~mask; + continue; + } + regs[i]->override->val &= ~mask; regs[i]->override->val |= (v << shift) & mask; regs[i]->override->mask |= mask; -- cgit v1.2.3