From: Dominik Brodowski <linux@xxxxxxxxxxxxxxxxxxxx> commit 8ecc4979b1bd9c94168e6fc92960033b7a951336 upstream. Only CPUs which speculate can speculate. Therefore, it seems prudent to test for cpu_no_speculation first and only then determine whether a specific speculating CPU is susceptible to store bypass speculation. This is underlined by all CPUs currently listed in cpu_no_speculation were present in cpu_no_spec_store_bypass as well. Signed-off-by: Dominik Brodowski <linux@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: bp@xxxxxxx Cc: konrad.wilk@xxxxxxxxxx Link: https://lkml.kernel.org/r/20180522090539.GA24668@xxxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/x86/kernel/cpu/common.c | 22 +++++++--------------- 1 file changed, 7 insertions(+), 15 deletions(-) --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -859,12 +859,8 @@ static const __initconst struct x86_cpu_ {} }; +/* Only list CPUs which speculate but are non susceptible to SSB */ static const __initconst struct x86_cpu_id cpu_no_spec_store_bypass[] = { - { X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_PINEVIEW }, - { X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_LINCROFT }, - { X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_PENWELL }, - { X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_CLOVERVIEW }, - { X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_CEDARVIEW }, { X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_SILVERMONT1 }, { X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_AIRMONT }, { X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_SILVERMONT2 }, @@ -872,14 +868,10 @@ static const __initconst struct x86_cpu_ { X86_VENDOR_INTEL, 6, INTEL_FAM6_CORE_YONAH }, { X86_VENDOR_INTEL, 6, INTEL_FAM6_XEON_PHI_KNL }, { X86_VENDOR_INTEL, 6, INTEL_FAM6_XEON_PHI_KNM }, - { X86_VENDOR_CENTAUR, 5, }, - { X86_VENDOR_INTEL, 5, }, - { X86_VENDOR_NSC, 5, }, { X86_VENDOR_AMD, 0x12, }, { X86_VENDOR_AMD, 0x11, }, { X86_VENDOR_AMD, 0x10, }, { X86_VENDOR_AMD, 0xf, }, - { X86_VENDOR_ANY, 4, }, {} }; @@ -902,6 +894,12 @@ static void __init cpu_set_bug_bits(stru { u64 ia32_cap = 0; + if (x86_match_cpu(cpu_no_speculation)) + return; + + setup_force_cpu_bug(X86_BUG_SPECTRE_V1); + setup_force_cpu_bug(X86_BUG_SPECTRE_V2); + if (cpu_has(c, X86_FEATURE_ARCH_CAPABILITIES)) rdmsrl(MSR_IA32_ARCH_CAPABILITIES, ia32_cap); @@ -909,12 +907,6 @@ static void __init cpu_set_bug_bits(stru !(ia32_cap & ARCH_CAP_SSB_NO)) setup_force_cpu_bug(X86_BUG_SPEC_STORE_BYPASS); - if (x86_match_cpu(cpu_no_speculation)) - return; - - setup_force_cpu_bug(X86_BUG_SPECTRE_V1); - setup_force_cpu_bug(X86_BUG_SPECTRE_V2); - if (ia32_cap & ARCH_CAP_IBRS_ALL) setup_force_cpu_cap(X86_FEATURE_IBRS_ENHANCED);
