On Wed, 30 Jul 2025 at 10:22, Greg KH gregkh@linuxfoundation.org wrote:
On Wed, Jul 30, 2025 at 09:56:17AM +0530, Suchit Karunakaran wrote:
The logic to synthesize constant_tsc for Pentium 4s (Family 15) is wrong. Since INTEL_P4_PRESCOTT is numerically greater than INTEL_P4_WILLAMETTE, the logic always results in false and never sets X86_FEATURE_CONSTANT_TSC for any Pentium 4 model. The error was introduced while replacing the x86_model check with a VFM one. The original check was as follows: if ((c->x86 == 0xf && c->x86_model >= 0x03) || (c->x86 == 0x6 && c->x86_model >= 0x0e)) set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC);
What do you mean by "original check"? Before the change that caused this, or what it should be?
Original check in this context refers to the change before the erroneous code.
Fix the logic to cover all Pentium 4 models from Prescott (model 3) to Cedarmill (model 6) which is the last model released in Family 15.
Fixes: fadb6f569b10 ("x86/cpu/intel: Limit the non-architectural constant_tsc model checks")
Cc: stable@vger.kernel.org # v6.15
Signed-off-by: Suchit Karunakaran suchitkarunakaran@gmail.com
Nit, no blank lines beween all of those last lines. Hint, look at all of the patches on the mailing lists AND in the tree already, you have hundreds of thousands of examples here of how to format things :)
Sorry about it. Should I send a new version of the patch removing the blank lines?