Messages in this thread Patch in this message | | | Date | Thu, 10 Jan 2019 17:00:54 +0100 | From | Borislav Petkov <> | Subject | Re: General protection fault in `switch_mm_irqs_off()` |
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On Thu, Jan 10, 2019 at 02:57:40PM +0100, Paul Menzel wrote: > Thank you very much. Indeed, the machine does not crash. I used Linus’ > master branch for testing, and applied your patch on top. Please find > the full log attached.
> 80.649: [ 3.197107] Spectre V2 : spectre_v2_user_select_mitigation: set X86_FEATURE_USE_IBPB
This is amazing.
Ok, next diff, same exercise. Thx.
--- diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h index dad12b767ba0..528ef8336f5f 100644 --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -284,6 +284,12 @@ static inline void indirect_branch_prediction_barrier(void) { u64 val = PRED_CMD_IBPB; + if (WARN_ON(boot_cpu_has(X86_FEATURE_USE_IBPB))) { + pr_info("%s: c: %px, array: 0x%x\n", + __func__, &boot_cpu_data, boot_cpu_data.x86_capability[7]); + return; + } + alternative_msr_write(MSR_IA32_PRED_CMD, val, X86_FEATURE_USE_IBPB); } diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 8654b8b0c848..e818e5abe611 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -371,6 +371,9 @@ spectre_v2_user_select_mitigation(enum spectre_v2_mitigation_cmd v2_cmd) if (boot_cpu_has(X86_FEATURE_IBPB)) { setup_force_cpu_cap(X86_FEATURE_USE_IBPB); + pr_err("%s: set X86_FEATURE_USE_IBPB, c: %px, array: 0x%x\n", + __func__, &boot_cpu_data, boot_cpu_data.x86_capability[7]); + switch (cmd) { case SPECTRE_V2_USER_CMD_FORCE: case SPECTRE_V2_USER_CMD_PRCTL_IBPB: diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index cb28e98a0659..8566737fa500 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -765,6 +765,9 @@ static void apply_forced_caps(struct cpuinfo_x86 *c) c->x86_capability[i] &= ~cpu_caps_cleared[i]; c->x86_capability[i] |= cpu_caps_set[i]; } + + if (c == &boot_cpu_data) + pr_info("%s: c: %px, array: 0x%x\n", __func__, c, c->x86_capability[7]); } static void init_speculation_control(struct cpuinfo_x86 *c) @@ -778,6 +781,10 @@ static void init_speculation_control(struct cpuinfo_x86 *c) if (cpu_has(c, X86_FEATURE_SPEC_CTRL)) { set_cpu_cap(c, X86_FEATURE_IBRS); set_cpu_cap(c, X86_FEATURE_IBPB); + + pr_info("%s: X86_FEATURE_SPEC_CTRL: c: %px, array: 0x%x, CPUID: 0x%x\n", + __func__, c, c->x86_capability[7], cpuid_edx(7)); + set_cpu_cap(c, X86_FEATURE_MSR_SPEC_CTRL); } @@ -793,9 +800,13 @@ static void init_speculation_control(struct cpuinfo_x86 *c) set_cpu_cap(c, X86_FEATURE_MSR_SPEC_CTRL); } - if (cpu_has(c, X86_FEATURE_AMD_IBPB)) + if (cpu_has(c, X86_FEATURE_AMD_IBPB)) { set_cpu_cap(c, X86_FEATURE_IBPB); + pr_info("%s: X86_FEATURE_AMD_IBPB: c: %px, array: 0x%x, CPUID: 0x%x\n", + __func__, c, c->x86_capability[7], cpuid_ebx(0x80000008)); + } + if (cpu_has(c, X86_FEATURE_AMD_STIBP)) { set_cpu_cap(c, X86_FEATURE_STIBP); set_cpu_cap(c, X86_FEATURE_MSR_SPEC_CTRL); -- Regards/Gruss, Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
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