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keydata= xsDiBFk3nEQRBADAEaSw6zC/EJkiwGPXbWtPxl2xCdSoeepS07jW8UgcHNurfHvUzogEq5xk hu507c3BarVjyWCJOylMNR98Yd8VqD9UfmX0Hb8/BrA+Hl6/DB/eqGptrf4BSRwcZQM32aZK 7Pj2XbGWIUrZrd70x1eAP9QE3P79Y2oLrsCgbZJfEwCgvz9JjGmQqQkRiTVzlZVCJYcyGGsD /0tbFCzD2h20ahe8rC1gbb3K3qk+LpBtvjBu1RY9drYk0NymiGbJWZgab6t1jM7sk2vuf0Py O9Hf9XBmK0uE9IgMaiCpc32XV9oASz6UJebwkX+zF2jG5I1BfnO9g7KlotcA/v5ClMjgo6Gl MDY4HxoSRu3i1cqqSDtVlt+AOVBJBACrZcnHAUSuCXBPy0jOlBhxPqRWv6ND4c9PH1xjQ3NP nxJuMBS8rnNg22uyfAgmBKNLpLgAGVRMZGaGoJObGf72s6TeIqKJo/LtggAS9qAUiuKVnygo 3wjfkS9A3DRO+SpU7JqWdsveeIQyeyEJ/8PTowmSQLakF+3fote9ybzd880fSmFuIEJldWxp Y2ggPGpiZXVsaWNoQHN1c2UuY29tPsJgBBMRAgAgBQJZN5xEAhsDBgsJCAcDAgQVAggDBBYC AwECHgECF4AACgkQoDSui/t3IH4J+wCfQ5jHdEjCRHj23O/5ttg9r9OIruwAn3103WUITZee e7Sbg12UgcQ5lv7SzsFNBFk3nEQQCACCuTjCjFOUdi5Nm244F+78kLghRcin/awv+IrTcIWF hUpSs1Y91iQQ7KItirz5uwCPlwejSJDQJLIS+QtJHaXDXeV6NI0Uef1hP20+y8qydDiVkv6l IreXjTb7DvksRgJNvCkWtYnlS3mYvQ9NzS9PhyALWbXnH6sIJd2O9lKS1Mrfq+y0IXCP10eS FFGg+Av3IQeFatkJAyju0PPthyTqxSI4lZYuJVPknzgaeuJv/2NccrPvmeDg6Coe7ZIeQ8Yj t0ARxu2xytAkkLCel1Lz1WLmwLstV30g80nkgZf/wr+/BXJW/oIvRlonUkxv+IbBM3dX2OV8 AmRv1ySWPTP7AAMFB/9PQK/VtlNUJvg8GXj9ootzrteGfVZVVT4XBJkfwBcpC/XcPzldjv+3 HYudvpdNK3lLujXeA5fLOH+Z/G9WBc5pFVSMocI71I8bT8lIAzreg0WvkWg5V2WZsUMlnDL9 mpwIGFhlbM3gfDMs7MPMu8YQRFVdUvtSpaAs8OFfGQ0ia3LGZcjA6Ik2+xcqscEJzNH+qh8V m5jjp28yZgaqTaRbg3M/+MTbMpicpZuqF4rnB0AQD12/3BNWDR6bmh+EkYSMcEIpQmBM51qM EKYTQGybRCjpnKHGOxG0rfFY1085mBDZCH5Kx0cl0HVJuQKC+dV2ZY5AqjcKwAxpE75MLFkr wkkEGBECAAkFAlk3nEQCGwwACgkQoDSui/t3IH7nnwCfcJWUDUFKdCsBH/E5d+0ZnMQi+G0A nAuWpQkjM1ASeQwSHEeAWPgskBQL In-Reply-To: <20260907213231.3159241-1-andrew.cooper3@citrix.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-purgate-ID: tlsNG-c201ff/1788848793-F4AA72A1-23E0712B/0/0 X-purgate-type: clean X-purgate-size: 2359 On 07.09.2026 23:32, Andrew Cooper wrote: > @@ -273,6 +274,44 @@ static bool microcode_fits_cpu(const struct microcode_patch *mc) > return false; > } > > +static bool microcode_safe_to_load(const struct microcode_patch *mc) > +{ > + struct cpu_signature *cpu_sig = &this_cpu(cpu_sig); > + > + /* > + * Treat pre-production as always safe - anyone using pre-production > + * microcode knows what they are doing, and can keep any resulting pieces. > + */ > + if ( (int)cpu_sig->rev < 0 || mc->rev < 0 ) > + return true; > + > + /* > + * GNR98 states that Granite Rapids systems hang when loading new ucode on > + * sufficiently old firmware. GNR101 retroactively declares that one > + * ucode had incorrect min_rev fields, in light of discovering GNR98. We still have no min_rev field, so imo a reference to it wants some clarification. Really I first meant to ask why there's no use of that field, to merely make that one exception. > + * Both are incomplete statements of the problem. > + * > + * At the time of writing (August 2026), the believed safe sequence is: > + * 0x01000370 -> [0x01000380...0x010003f3] -> 0x01000405 -> any later > + * > + * Disallow known-unsafe loads while permitting believed-safe loads. For > + * GNR, this allows multi-hop loading to get up to the latest. > + */ > + if ( boot_cpu_data.vfm == INTEL_GRANITERAPIDS_X && > + boot_cpu_data.stepping == 1 && (cpu_sig->pf & 0x95) && > + ((cpu_sig->rev < 0x01000380 && mc->rev >= 0x01000405) || This is odd: The lhs of && uses the lower bound of the inner permitted range, while the rhs of the && doesn't use the upper one. If it's intended that way, I think this also needs clarifying in the comment. Otherwise imo lhs and rhs better would be consistent in this regard. > + (cpu_sig->rev < 0x01000405 && mc->rev > 0x01000405)) ) This one, otoh, fully matches the comment. > + { > + printk_once(XENLOG_WARNING > + "microcode: Granite Rapids erratum GNR98 detected. Skipping ucode 0x%08x\n" > + "microcode: Firmware update recommended\n", mc->rev); I think a 2nd XENLOG_WARNING is wanted after the inner \n (or none at all, to use the default for both). Jan