The following commit has been merged into the x86/cpu branch of tip: Commit-ID: 75ab6506acbc494a838dc8bc5fbbde7092f71b33 Gitweb: https://git.kernel.org/tip/75ab6506acbc494a838dc8bc5fbbde7092f71b33 Author: Brendan Jackman <jackmanb@xxxxxxxxxx> AuthorDate: Mon, 03 Mar 2025 15:45:39 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitterDate: Mon, 03 Mar 2025 21:23:39 +01:00 x86/cpu: Log CPU flag cmdline hacks more verbosely Since using these options is very dangerous, make details as visible as possible: - Instead of a single message for each of the cmdline options, print a separate pr_warn() for each individual flag. - Say explicitly whether the flag is a "feature" or a "bug". Suggested-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Signed-off-by: Brendan Jackman <jackmanb@xxxxxxxxxx> Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Acked-by: Borislav Petkov (AMD) <bp@xxxxxxxxx> Link: https://lore.kernel.org/r/20250303-setcpuid-taint-louder-v1-3-8d255032cb4c@xxxxxxxxxx --- arch/x86/kernel/cpu/common.c | 39 ++++++++++++++++++++--------------- 1 file changed, 23 insertions(+), 16 deletions(-) diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index c1ced31..8eba9ca 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1484,8 +1484,6 @@ static inline bool parse_set_clear_cpuid(char *arg, bool set) char *opt; int taint = 0; - pr_warn("%s CPUID bits:", set ? "Force-enabling" : "Clearing"); - while (arg) { bool found __maybe_unused = false; unsigned int bit; @@ -1500,16 +1498,19 @@ static inline bool parse_set_clear_cpuid(char *arg, bool set) if (!kstrtouint(opt, 10, &bit)) { if (bit < NCAPINTS * 32) { + if (set) { + pr_warn("setcpuid: force-enabling CPU feature flag:"); + setup_force_cpu_cap(bit); + } else { + pr_warn("clearcpuid: force-disabling CPU feature flag:"); + setup_clear_cpu_cap(bit); + } /* empty-string, i.e., ""-defined feature flags */ if (!x86_cap_flags[bit]) - pr_cont(" %d:%d", bit >> 5, bit & 31); + pr_cont(" %d:%d\n", bit >> 5, bit & 31); else - pr_cont(" %s", x86_cap_flags[bit]); + pr_cont(" %s\n", x86_cap_flags[bit]); - if (set) - setup_force_cpu_cap(bit); - else - setup_clear_cpu_cap(bit); taint++; } /* @@ -1521,11 +1522,15 @@ static inline bool parse_set_clear_cpuid(char *arg, bool set) for (bit = 0; bit < 32 * (NCAPINTS + NBUGINTS); bit++) { const char *flag; + const char *kind; - if (bit < 32 * NCAPINTS) + if (bit < 32 * NCAPINTS) { flag = x86_cap_flags[bit]; - else + kind = "feature"; + } else { + kind = "bug"; flag = x86_bug_flags[bit - (32 * NCAPINTS)]; + } if (!flag) continue; @@ -1533,22 +1538,24 @@ static inline bool parse_set_clear_cpuid(char *arg, bool set) if (strcmp(flag, opt)) continue; - pr_cont(" %s", opt); - if (set) + if (set) { + pr_warn("setcpuid: force-enabling CPU %s flag: %s\n", + kind, flag); setup_force_cpu_cap(bit); - else + } else { + pr_warn("clearcpuid: force-disabling CPU %s flag: %s\n", + kind, flag); setup_clear_cpu_cap(bit); + } taint++; found = true; break; } if (!found) - pr_cont(" (unknown: %s)", opt); + pr_warn("%s: unknown CPU flag: %s", set ? "setcpuid" : "clearcpuid", opt); } - pr_cont("\n"); - return taint; }
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