[PATCH 1/2] x86: Don't clear X86_BUG_F00F before setting it

[Richard Weinberger]

On x86 SMP systems with the F00F bug is present the following
warning occurs for each application processor:

[    0.013122] ------------[ cut here ]------------
[    0.013122] WARNING: arch/x86/kernel/cpu/cpuid-deps.c:126 at do_clear_cpu_cap+0xb4/0x110, CPU#1: swapper/1/0
[    0.013122] Modules linked in:
[    0.013122] CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted 6.19.0-10445-g0f2acd3148e0 #379 PREEMPT(full)
[    0.013122] Hardware name:  , BIOS 4.51 PG 04/03/97
[    0.013122] EIP: do_clear_cpu_cap+0xb4/0x110
[    0.013122] Code: 08 83 c7 08 85 c0 75 ce 84 d2 75 c2 8b 45 f0 64 2b 05 08 80 af c4 75 64 83 c4 68 5b 5e 5f 5d c3 8b 0d 78 7a a1 c4 85 c9 74 83 <0f> 0b e9 7c ff ff ff 2e 8d 74 26 00 b8 20 79 a1 c4 89 55 8c e8 33
[    0.013122] EAX: 00000000 EBX: c1143ed8 ECX: 00000001 EDX: 000002c0
[    0.013122] ESI: c7ee8060 EDI: c1143f38 EBP: c1143f48 ESP: c1143ed4
[    0.013122] DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 EFLAGS: 00210002
[    0.013122] CR0: 80050033 CR2: 00000000 CR3: 04b15000 CR4: 00000010
[    0.013122] Call Trace:
[    0.013122]  clear_cpu_cap+0x8/0x10
[    0.013122]  init_intel+0x1b/0x4b0
[    0.013122]  identify_cpu+0x154/0x750
[    0.013122]  identify_secondary_cpu+0x3d/0x90
[    0.013122]  start_secondary+0x6b/0xf0
[    0.013122]  startup_32_smp+0x151/0x160
[    0.013122] ---[ end trace 0000000000000000 ]---

Commit ee8962082a44 ("x86/alternatives: Catch late X86_FEATURE modifiers") introduced the warning
to catch changes to x86 features after alternatives have been applied.

Since the X86_BUG_F00F CPU feature is first cleared in
intel_workarounds() and then set for the affected families, the feature
flags are unnecessarily modified. On systems where the F00F bug is
actually present, clearing the flag first triggers the warning.

Fix this by not clearing the flag first. Clearing it first is relict from
commit e2604b49e8a8 ("x86, cpu: Convert F00F bug detection").

Fixes: ee8962082a44 ("x86/alternatives: Catch late X86_FEATURE modifiers")
Signed-off-by: Richard Weinberger <richard@xxxxxx>
---
 arch/x86/kernel/cpu/intel.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 646ff33c4651..73f6bf182333 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -394,7 +394,6 @@ static void intel_workarounds(struct cpuinfo_x86 *c)
 	 * system. Announce that the fault handler will be checking for it.
 	 * The Quark is also family 5, but does not have the same bug.
 	 */
-	clear_cpu_bug(c, X86_BUG_F00F);
 	if (c->x86_vfm >= INTEL_FAM5_START && c->x86_vfm < INTEL_QUARK_X1000) {
 		static int f00f_workaround_enabled;
 
-- 
2.51.0