On 24/05/30 06:24PM, Thomas Gleixner wrote:
On Thu, May 30 2024 at 17:53, Thomas Gleixner wrote:
Let me figure out how to fix that sanely.
The proper fix is obviously to unlock CPUID on Intel _before_ anything which depends on cpuid_level is evaluated.
Thanks,
tglx
Hey Thomas,
as reported on the other mail the proposed fix broke the build (see below) due to get_cpu_cap() becoming static but still being used in other parts of the code.
One of the reporters in the Arch Bugtracker with an Intel Core i7-7700k has tested a modified version of this fix[0] with the static change reversed on top of the 6.9.2 stable kernel and reports that the patch does not fix the issue for them. I have attached their output for the patched (dmesg6.9.2-1.5.log) and nonpatched (dmesg6.9.2-1.log) kernel.
Should we also get them to test the mainline version or do you need any other debug output?
Cheers, gromit
[0]: https://gitlab.archlinux.org/archlinux/packaging/packages/linux/-/issues/57#...
--- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -969,7 +969,7 @@ static void init_speculation_control(str } } -void get_cpu_cap(struct cpuinfo_x86 *c) +static void get_cpu_cap(struct cpuinfo_x86 *c)
making this function static breaks the build for me:
arch/x86/xen/enlighten_pv.c: In function ‘xen_start_kernel’: arch/x86/xen/enlighten_pv.c:1388:9: error: implicit declaration of function ‘get_cpu_cap’; did you mean ‘set_cpu_cap’? [-Wimplicit-function-declaration] 1388 | get_cpu_cap(&boot_cpu_data); ¦ | ^~~~~~~~~~~ ¦ | set_cpu_cap
{ u32 eax, ebx, ecx, edx; @@ -1585,6 +1585,7 @@ static void __init early_identify_cpu(st if (have_cpuid_p()) { cpu_detect(c); get_cpu_vendor(c);
intel_unlock_cpuid_leafs(c);@@ -1744,7 +1745,7 @@ static void generic_identify(struct cpui cpu_detect(c); get_cpu_vendor(c);
- intel_unlock_cpuid_leafs(c); get_cpu_cap(c);
get_cpu_address_sizes(c); --- a/arch/x86/kernel/cpu/cpu.h +++ b/arch/x86/kernel/cpu/cpu.h @@ -61,14 +61,15 @@ extern __ro_after_init enum tsx_ctrl_sta extern void __init tsx_init(void); void tsx_ap_init(void); +void intel_unlock_cpuid_leafs(struct cpuinfo_x86 *c); #else static inline void tsx_init(void) { } static inline void tsx_ap_init(void) { } +static inline void intel_unlock_cpuid_leafs(struct cpuinfo_x86 *c) { } #endif /* CONFIG_CPU_SUP_INTEL */ extern void init_spectral_chicken(struct cpuinfo_x86 *c); -extern void get_cpu_cap(struct cpuinfo_x86 *c); extern void get_cpu_address_sizes(struct cpuinfo_x86 *c); extern void cpu_detect_cache_sizes(struct cpuinfo_x86 *c); extern void init_scattered_cpuid_features(struct cpuinfo_x86 *c); --- a/arch/x86/kernel/cpu/intel.c +++ b/arch/x86/kernel/cpu/intel.c @@ -269,19 +269,26 @@ static void detect_tme_early(struct cpui c->x86_phys_bits -= keyid_bits; } +void intel_unlock_cpuid_leafs(struct cpuinfo_x86 *c) +{
- if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL)
return;- if (c->x86 < 6 || (c->x86 == 6 && c->x86_model < 0xd))
return;- /*
* The BIOS can have limited CPUID to leaf 2, which breaks feature* enumeration. Unlock it and update the maximum leaf info.*/- if (msr_clear_bit(MSR_IA32_MISC_ENABLE, MSR_IA32_MISC_ENABLE_LIMIT_CPUID_BIT) > 0)
c->cpuid_level = cpuid_eax(0);+}
static void early_init_intel(struct cpuinfo_x86 *c) { u64 misc_enable;
- /* Unmask CPUID levels if masked: */
- if (c->x86 > 6 || (c->x86 == 6 && c->x86_model >= 0xd)) {
if (msr_clear_bit(MSR_IA32_MISC_ENABLE,MSR_IA32_MISC_ENABLE_LIMIT_CPUID_BIT) > 0) {c->cpuid_level = cpuid_eax(0);get_cpu_cap(c);}- }
- if ((c->x86 == 0xf && c->x86_model >= 0x03) || (c->x86 == 0x6 && c->x86_model >= 0x0e)) set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC);