6.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Thomas Gleixner tglx@linutronix.de
commit 0c2f6d04619ec2b53ad4b0b591eafc9389786e86 upstream.
Intel CPUs have a MSR bit to limit CPUID enumeration to leaf two. If this bit is set by the BIOS then CPUID evaluation including topology enumeration does not work correctly as the evaluation code does not try to analyze any leaf greater than two.
This went unnoticed before because the original topology code just repeated evaluation several times and managed to overwrite the initial limited information with the correct one later. The new evaluation code does it once and therefore ends up with the limited and wrong information.
Cure this by unlocking CPUID right before evaluating anything which depends on the maximum CPUID leaf being greater than two instead of rereading stuff after unlock.
Fixes: 22d63660c35e ("x86/cpu: Use common topology code for Intel") Reported-by: Peter Schneider pschneider1968@googlemail.com Signed-off-by: Thomas Gleixner tglx@linutronix.de Signed-off-by: Borislav Petkov (AMD) bp@alien8.de Tested-by: Peter Schneider pschneider1968@googlemail.com Cc: stable@kernel.org Link: https://lore.kernel.org/r/fd3f73dc-a86f-4bcf-9c60-43556a21eb42@googlemail.co... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kernel/cpu/common.c | 3 ++- arch/x86/kernel/cpu/cpu.h | 2 ++ arch/x86/kernel/cpu/intel.c | 25 ++++++++++++++++--------- 3 files changed, 20 insertions(+), 10 deletions(-)
--- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1589,6 +1589,7 @@ static void __init early_identify_cpu(st if (have_cpuid_p()) { cpu_detect(c); get_cpu_vendor(c); + intel_unlock_cpuid_leafs(c); get_cpu_cap(c); setup_force_cpu_cap(X86_FEATURE_CPUID); get_cpu_address_sizes(c); @@ -1748,7 +1749,7 @@ 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 @@ -61,9 +61,11 @@ 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); --- a/arch/x86/kernel/cpu/intel.c +++ b/arch/x86/kernel/cpu/intel.c @@ -268,19 +268,26 @@ detect_keyid_bits: 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);