diff options
| -rw-r--r-- | arch/x86/kernel/process.c | 46 |
1 files changed, 29 insertions, 17 deletions
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 8aa49604f9ae..70e9832379e1 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -395,27 +395,40 @@ static __always_inline void amd_set_ssb_virt_state(unsigned long tifn) wrmsrl(MSR_AMD64_VIRT_SPEC_CTRL, ssbd_tif_to_spec_ctrl(tifn)); } -static __always_inline void spec_ctrl_update_msr(unsigned long tifn) -{ - u64 msr = x86_spec_ctrl_base | ssbd_tif_to_spec_ctrl(tifn); - - wrmsrl(MSR_IA32_SPEC_CTRL, msr); -} +/* + * Update the MSRs managing speculation control, during context switch. + * + * tifp: Previous task's thread flags + * tifn: Next task's thread flags + */ +static __always_inline void __speculation_ctrl_update(unsigned long tifp, + unsigned long tifn) +{ + u64 msr = x86_spec_ctrl_base; + bool updmsr = false; + + /* If TIF_SSBD is different, select the proper mitigation method */ + if ((tifp ^ tifn) & _TIF_SSBD) { + if (static_cpu_has(X86_FEATURE_VIRT_SSBD)) { + amd_set_ssb_virt_state(tifn); + } else if (static_cpu_has(X86_FEATURE_LS_CFG_SSBD)) { + amd_set_core_ssb_state(tifn); + } else if (static_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD) || + static_cpu_has(X86_FEATURE_AMD_SSBD)) { + msr |= ssbd_tif_to_spec_ctrl(tifn); + updmsr = true; + } + } -static __always_inline void __speculation_ctrl_update(unsigned long tifn) -{ - if (static_cpu_has(X86_FEATURE_VIRT_SSBD)) - amd_set_ssb_virt_state(tifn); - else if (static_cpu_has(X86_FEATURE_LS_CFG_SSBD)) - amd_set_core_ssb_state(tifn); - else - spec_ctrl_update_msr(tifn); + if (updmsr) + wrmsrl(MSR_IA32_SPEC_CTRL, msr); } void speculation_ctrl_update(unsigned long tif) { + /* Forced update. Make sure all relevant TIF flags are different */ preempt_disable(); - __speculation_ctrl_update(tif); + __speculation_ctrl_update(~tif, tif); preempt_enable(); } @@ -451,8 +464,7 @@ void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p, if ((tifp ^ tifn) & _TIF_NOCPUID) set_cpuid_faulting(!!(tifn & _TIF_NOCPUID)); - if ((tifp ^ tifn) & _TIF_SSBD) - __speculation_ctrl_update(tifn); + __speculation_ctrl_update(tifp, tifn); } /* |