/* * Called immediately after a successful exec. */ void arch_setup_new_exec(void) { /* If cpuid was previously disabled for this task, re-enable it. */ if (test_thread_flag(TIF_NOCPUID)) enable_cpuid(); /* * Don't inherit TIF_SSBD across exec boundary when * PR_SPEC_DISABLE_NOEXEC is used. */ if (test_thread_flag(TIF_SSBD) && task_spec_ssb_noexec(current)) { clear_thread_flag(TIF_SSBD); task_clear_spec_ssb_disable(current); task_clear_spec_ssb_noexec(current); speculation_ctrl_update(task_thread_info(current)->flags); } }
void x86_virt_spec_ctrl(u64 guest_spec_ctrl, u64 guest_virt_spec_ctrl, bool setguest) { u64 msrval, guestval, hostval = x86_spec_ctrl_base; struct thread_info *ti = current_thread_info(); /* Is MSR_SPEC_CTRL implemented ? */ if (static_cpu_has(X86_FEATURE_MSR_SPEC_CTRL)) { /* * Restrict guest_spec_ctrl to supported values. Clear the * modifiable bits in the host base value and or the * modifiable bits from the guest value. */ guestval = hostval & ~x86_spec_ctrl_mask; guestval |= guest_spec_ctrl & x86_spec_ctrl_mask; /* SSBD controlled in MSR_SPEC_CTRL */ if (static_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD) || static_cpu_has(X86_FEATURE_AMD_SSBD)) hostval |= ssbd_tif_to_spec_ctrl(ti->flags); /* Conditional STIBP enabled? */ if (static_branch_unlikely(&switch_to_cond_stibp)) hostval |= stibp_tif_to_spec_ctrl(ti->flags); if (hostval != guestval) { msrval = setguest ? guestval : hostval; wrmsrl(MSR_IA32_SPEC_CTRL, msrval); } } /* * If SSBD is not handled in MSR_SPEC_CTRL on AMD, update * MSR_AMD64_L2_CFG or MSR_VIRT_SPEC_CTRL if supported. */ if (!static_cpu_has(X86_FEATURE_LS_CFG_SSBD) && !static_cpu_has(X86_FEATURE_VIRT_SSBD)) return; /* * If the host has SSBD mitigation enabled, force it in the host's * virtual MSR value. If its not permanently enabled, evaluate * current's TIF_SSBD thread flag. */ if (static_cpu_has(X86_FEATURE_SPEC_STORE_BYPASS_DISABLE)) hostval = SPEC_CTRL_SSBD; else hostval = ssbd_tif_to_spec_ctrl(ti->flags); /* Sanitize the guest value */ guestval = guest_virt_spec_ctrl & SPEC_CTRL_SSBD; if (hostval != guestval) { unsigned long tif; tif = setguest ? ssbd_spec_ctrl_to_tif(guestval) : ssbd_spec_ctrl_to_tif(hostval); speculation_ctrl_update(tif); } }