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openSUSE:Leap:15.5:Update
xen.23267
6202afa3-x86-clean-up-MSR_MCU_OPT_CTRL-handling...
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File 6202afa3-x86-clean-up-MSR_MCU_OPT_CTRL-handling.patch of Package xen.23267
# Commit 39a40f3835efcc25c1b05a25c321a01d7e11cbd7 # Date 2022-02-08 18:00:08 +0000 # Author Andrew Cooper <andrew.cooper3@citrix.com> # Committer Andrew Cooper <andrew.cooper3@citrix.com> x86/spec-ctrl: Clean up MSR_MCU_OPT_CTRL handling Introduce cpu_has_srbds_ctrl as more users are going to appear shortly. MSR_MCU_OPT_CTRL is gaining extra functionality, meaning that the current default_xen_mcu_opt_ctrl is no longer a good fit. Introduce two new helpers, update_mcu_opt_ctrl() which does a full RMW cycle on the MSR, and set_in_mcu_opt_ctrl() which lets callers configure specific bits at a time without clobbering each others settings. No functional change. Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> Reviewed-by: Jan Beulich <jbeulich@suse.com> --- a/xen/arch/x86/acpi/power.c +++ b/xen/arch/x86/acpi/power.c @@ -299,8 +299,7 @@ static int enter_state(u32 state) ci->last_spec_ctrl = default_xen_spec_ctrl; } - if ( boot_cpu_has(X86_FEATURE_SRBDS_CTRL) ) - wrmsrl(MSR_MCU_OPT_CTRL, default_xen_mcu_opt_ctrl); + update_mcu_opt_ctrl(); /* (re)initialise SYSCALL/SYSENTER state, amongst other things. */ percpu_traps_init(); --- a/xen/arch/x86/cpu/intel.c +++ b/xen/arch/x86/cpu/intel.c @@ -15,6 +15,38 @@ #include "cpu.h" /* + * MSR_MCU_OPT_CTRL is a collection of unrelated functionality, with separate + * enablement requirements, but which want to be consistent across the system. + */ +static uint32_t __read_mostly mcu_opt_ctrl_mask; +static uint32_t __read_mostly mcu_opt_ctrl_val; + +void update_mcu_opt_ctrl(void) +{ + uint32_t mask = mcu_opt_ctrl_mask, lo, hi; + + if ( !mask ) + return; + + rdmsr(MSR_MCU_OPT_CTRL, lo, hi); + + lo &= ~mask; + lo |= mcu_opt_ctrl_val; + + wrmsr(MSR_MCU_OPT_CTRL, lo, hi); +} + +void __init set_in_mcu_opt_ctrl(uint32_t mask, uint32_t val) +{ + mcu_opt_ctrl_mask |= mask; + + mcu_opt_ctrl_val &= ~mask; + mcu_opt_ctrl_val |= (val & mask); + + update_mcu_opt_ctrl(); +} + +/* * Processors which have self-snooping capability can handle conflicting * memory type across CPUs by snooping its own cache. However, there exists * CPU models in which having conflicting memory types still leads to --- a/xen/include/asm-x86/cpufeature.h +++ b/xen/include/asm-x86/cpufeature.h @@ -133,6 +133,7 @@ /* CPUID level 0x00000007:0.edx */ #define cpu_has_avx512_4vnniw boot_cpu_has(X86_FEATURE_AVX512_4VNNIW) #define cpu_has_avx512_4fmaps boot_cpu_has(X86_FEATURE_AVX512_4FMAPS) +#define cpu_has_srbds_ctrl boot_cpu_has(X86_FEATURE_SRBDS_CTRL) #define cpu_has_rtm_always_abort boot_cpu_has(X86_FEATURE_RTM_ALWAYS_ABORT) #define cpu_has_tsx_force_abort boot_cpu_has(X86_FEATURE_TSX_FORCE_ABORT) #define cpu_has_serialize boot_cpu_has(X86_FEATURE_SERIALIZE) --- a/xen/include/asm-x86/processor.h +++ b/xen/include/asm-x86/processor.h @@ -632,6 +632,9 @@ extern int8_t opt_tsx, cpu_has_tsx_ctrl; extern bool rtm_disabled; void tsx_init(void); +void update_mcu_opt_ctrl(void); +void set_in_mcu_opt_ctrl(uint32_t mask, uint32_t val); + #endif /* !__ASSEMBLY__ */ #endif /* __ASM_X86_PROCESSOR_H */ --- a/xen/include/asm-x86/spec_ctrl.h +++ b/xen/include/asm-x86/spec_ctrl.h @@ -54,8 +54,6 @@ extern int8_t opt_pv_l1tf_hwdom, opt_pv_ */ extern paddr_t l1tf_addr_mask, l1tf_safe_maddr; -extern uint64_t default_xen_mcu_opt_ctrl; - static inline void init_shadow_spec_ctrl_state(void) { struct cpu_info *info = get_cpu_info(); --- a/xen/arch/x86/smpboot.c +++ b/xen/arch/x86/smpboot.c @@ -383,8 +383,7 @@ void start_secondary(void *unused) wrmsrl(MSR_SPEC_CTRL, default_xen_spec_ctrl); info->last_spec_ctrl = default_xen_spec_ctrl; } - if ( boot_cpu_has(X86_FEATURE_SRBDS_CTRL) ) - wrmsrl(MSR_MCU_OPT_CTRL, default_xen_mcu_opt_ctrl); + update_mcu_opt_ctrl(); tsx_init(); /* Needs microcode. May change HLE/RTM feature bits. */ --- a/xen/arch/x86/spec_ctrl.c +++ b/xen/arch/x86/spec_ctrl.c @@ -67,7 +67,6 @@ static bool __initdata cpu_has_bug_msbds static bool __initdata cpu_has_bug_mds; /* Any other M{LP,SB,FB}DS combination. */ static int8_t __initdata opt_srb_lock = -1; -uint64_t __read_mostly default_xen_mcu_opt_ctrl; static int __init parse_spec_ctrl(const char *s) { @@ -376,7 +375,7 @@ static void __init print_details(enum in (default_xen_spec_ctrl & SPEC_CTRL_SSBD) ? " SSBD+" : " SSBD-", !(caps & ARCH_CAPS_TSX_CTRL) ? "" : (opt_tsx & 1) ? " TSX+" : " TSX-", - !boot_cpu_has(X86_FEATURE_SRBDS_CTRL) ? "" : + !cpu_has_srbds_ctrl ? "" : opt_srb_lock ? " SRB_LOCK+" : " SRB_LOCK-", opt_ibpb ? " IBPB" : "", opt_l1d_flush ? " L1D_FLUSH" : "", @@ -1203,32 +1202,24 @@ void __init init_speculation_mitigations tsx_init(); } - /* Calculate suitable defaults for MSR_MCU_OPT_CTRL */ - if ( boot_cpu_has(X86_FEATURE_SRBDS_CTRL) ) + /* + * On some SRBDS-affected hardware, it may be safe to relax srb-lock by + * default. + * + * On parts which enumerate MDS_NO and not TAA_NO, TSX is the only known + * way to access the Fill Buffer. If TSX isn't available (inc. SKU + * reasons on some models), or TSX is explicitly disabled, then there is + * no need for the extra overhead to protect RDRAND/RDSEED. + */ + if ( cpu_has_srbds_ctrl ) { - uint64_t val; - - rdmsrl(MSR_MCU_OPT_CTRL, val); - - /* - * On some SRBDS-affected hardware, it may be safe to relax srb-lock - * by default. - * - * On parts which enumerate MDS_NO and not TAA_NO, TSX is the only way - * to access the Fill Buffer. If TSX isn't available (inc. SKU - * reasons on some models), or TSX is explicitly disabled, then there - * is no need for the extra overhead to protect RDRAND/RDSEED. - */ if ( opt_srb_lock == -1 && (caps & (ARCH_CAPS_MDS_NO|ARCH_CAPS_TAA_NO)) == ARCH_CAPS_MDS_NO && (!cpu_has_hle || ((caps & ARCH_CAPS_TSX_CTRL) && rtm_disabled)) ) opt_srb_lock = 0; - val &= ~MCU_OPT_CTRL_RNGDS_MITG_DIS; - if ( !opt_srb_lock ) - val |= MCU_OPT_CTRL_RNGDS_MITG_DIS; - - default_xen_mcu_opt_ctrl = val; + set_in_mcu_opt_ctrl(MCU_OPT_CTRL_RNGDS_MITG_DIS, + opt_srb_lock ? 0 : MCU_OPT_CTRL_RNGDS_MITG_DIS); } print_details(thunk, caps); @@ -1266,9 +1257,6 @@ void __init init_speculation_mitigations wrmsrl(MSR_SPEC_CTRL, val); info->last_spec_ctrl = val; } - - if ( boot_cpu_has(X86_FEATURE_SRBDS_CTRL) ) - wrmsrl(MSR_MCU_OPT_CTRL, default_xen_mcu_opt_ctrl); } static void __init __maybe_unused build_assertions(void)
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