diff options
| -rw-r--r-- | xen/arch/x86/acpi/power.c | 3 | ||||
| -rw-r--r-- | xen/arch/x86/setup.c | 5 | ||||
| -rw-r--r-- | xen/arch/x86/smpboot.c | 5 | ||||
| -rw-r--r-- | xen/arch/x86/spec_ctrl.c | 10 | ||||
| -rw-r--r-- | xen/include/asm-x86/current.h | 2 | ||||
| -rw-r--r-- | xen/include/asm-x86/spec_ctrl_asm.h | 4 |
6 files changed, 24 insertions, 5 deletions
diff --git a/xen/arch/x86/acpi/power.c b/xen/arch/x86/acpi/power.c index 0837a3ead4..bac9c16389 100644 --- a/xen/arch/x86/acpi/power.c +++ b/xen/arch/x86/acpi/power.c @@ -296,7 +296,10 @@ static int enter_state(u32 state) ci->spec_ctrl_flags |= (default_spec_ctrl_flags & SCF_ist_wrmsr); if ( boot_cpu_has(X86_FEATURE_IBRSB) ) + { wrmsrl(MSR_SPEC_CTRL, default_xen_spec_ctrl); + 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); diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c index da47cdea14..369691dd13 100644 --- a/xen/arch/x86/setup.c +++ b/xen/arch/x86/setup.c @@ -1944,9 +1944,12 @@ void __init noreturn __start_xen(unsigned long mbi_p) if ( bsp_delay_spec_ctrl ) { - get_cpu_info()->spec_ctrl_flags &= ~SCF_use_shadow; + struct cpu_info *info = get_cpu_info(); + + info->spec_ctrl_flags &= ~SCF_use_shadow; barrier(); wrmsrl(MSR_SPEC_CTRL, default_xen_spec_ctrl); + info->last_spec_ctrl = default_xen_spec_ctrl; } /* Jump to the 1:1 virtual mappings of cpu0_stack. */ diff --git a/xen/arch/x86/smpboot.c b/xen/arch/x86/smpboot.c index 329cfdb6c9..ee3e86cc78 100644 --- a/xen/arch/x86/smpboot.c +++ b/xen/arch/x86/smpboot.c @@ -322,6 +322,8 @@ static void set_cpu_sibling_map(unsigned int cpu) void start_secondary(void *unused) { + struct cpu_info *info = get_cpu_info(); + /* * Dont put anything before smp_callin(), SMP booting is so fragile that we * want to limit the things done here to the most necessary things. @@ -378,7 +380,10 @@ void start_secondary(void *unused) * microcode. */ if ( boot_cpu_has(X86_FEATURE_IBRSB) ) + { 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); diff --git a/xen/arch/x86/spec_ctrl.c b/xen/arch/x86/spec_ctrl.c index 2072daf662..b2fd86ebe5 100644 --- a/xen/arch/x86/spec_ctrl.c +++ b/xen/arch/x86/spec_ctrl.c @@ -1270,6 +1270,9 @@ void __init init_speculation_mitigations(void) */ if ( has_spec_ctrl ) { + struct cpu_info *info = get_cpu_info(); + unsigned int val; + bsp_delay_spec_ctrl = !cpu_has_hypervisor && default_xen_spec_ctrl; /* @@ -1278,15 +1281,16 @@ void __init init_speculation_mitigations(void) */ if ( bsp_delay_spec_ctrl ) { - struct cpu_info *info = get_cpu_info(); - info->shadow_spec_ctrl = 0; barrier(); info->spec_ctrl_flags |= SCF_use_shadow; barrier(); } - wrmsrl(MSR_SPEC_CTRL, bsp_delay_spec_ctrl ? 0 : default_xen_spec_ctrl); + val = bsp_delay_spec_ctrl ? 0 : default_xen_spec_ctrl; + + wrmsrl(MSR_SPEC_CTRL, val); + info->last_spec_ctrl = val; } if ( boot_cpu_has(X86_FEATURE_SRBDS_CTRL) ) diff --git a/xen/include/asm-x86/current.h b/xen/include/asm-x86/current.h index a74ad4bc4c..8ea4aecc5e 100644 --- a/xen/include/asm-x86/current.h +++ b/xen/include/asm-x86/current.h @@ -56,6 +56,7 @@ struct cpu_info { /* See asm-x86/spec_ctrl_asm.h for usage. */ unsigned int shadow_spec_ctrl; uint8_t xen_spec_ctrl; + uint8_t last_spec_ctrl; uint8_t spec_ctrl_flags; /* @@ -73,7 +74,6 @@ struct cpu_info { */ bool use_pv_cr3; - unsigned long __pad; /* get_stack_bottom() must be 16-byte aligned */ }; diff --git a/xen/include/asm-x86/spec_ctrl_asm.h b/xen/include/asm-x86/spec_ctrl_asm.h index bf82528a12..9c0c7622c4 100644 --- a/xen/include/asm-x86/spec_ctrl_asm.h +++ b/xen/include/asm-x86/spec_ctrl_asm.h @@ -67,6 +67,10 @@ * steps 2 and 6 will restore the shadow value rather than leaving Xen's value * loaded and corrupting the value used in guest context. * + * Additionally, in some cases it is safe to skip writes to MSR_SPEC_CTRL when + * we don't require any of the side effects of an identical write. Maintain a + * per-cpu last_spec_ctrl value for this purpose. + * * The following ASM fragments implement this algorithm. See their local * comments for further details. * - SPEC_CTRL_ENTRY_FROM_PV |