The following commit has been merged into the x86/urgent branch of tip: Commit-ID: f9e14dbbd454581061c736bf70bf5cbb15ac927c Gitweb: https://git.kernel.org/tip/f9e14dbbd454581061c736bf70bf5cbb15ac927c Author: Borislav Petkov <bp@xxxxxxx> AuthorDate: Tue, 19 Apr 2022 09:52:41 -07:00 Committer: Borislav Petkov <bp@xxxxxxx> CommitterDate: Tue, 19 Apr 2022 19:37:05 +02:00 x86/cpu: Load microcode during restore_processor_state() When resuming from system sleep state, restore_processor_state() restores the boot CPU MSRs. These MSRs could be emulated by microcode. If microcode is not loaded yet, writing to emulated MSRs leads to unchecked MSR access error: ... PM: Calling lapic_suspend+0x0/0x210 unchecked MSR access error: WRMSR to 0x10f (tried to write 0x0...0) at rIP: ... (native_write_msr) Call Trace: <TASK> ? restore_processor_state x86_acpi_suspend_lowlevel acpi_suspend_enter suspend_devices_and_enter pm_suspend.cold state_store kobj_attr_store sysfs_kf_write kernfs_fop_write_iter new_sync_write vfs_write ksys_write __x64_sys_write do_syscall_64 entry_SYSCALL_64_after_hwframe RIP: 0033:0x7fda13c260a7 To ensure microcode emulated MSRs are available for restoration, load the microcode on the boot CPU before restoring these MSRs. [ Pawan: write commit message and productize it. ] Fixes: e2a1256b17b1 ("x86/speculation: Restore speculation related MSRs during S3 resume") Reported-by: Kyle D. Pelton <kyle.d.pelton@xxxxxxxxx> Signed-off-by: Borislav Petkov <bp@xxxxxxx> Signed-off-by: Pawan Gupta <pawan.kumar.gupta@xxxxxxxxxxxxxxx> Tested-by: Kyle D. Pelton <kyle.d.pelton@xxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Link: https://bugzilla.kernel.org/show_bug.cgi?id=215841 Link: https://lore.kernel.org/r/4350dfbf785cd482d3fafa72b2b49c83102df3ce.1650386317.git.pawan.kumar.gupta@xxxxxxxxxxxxxxx --- arch/x86/include/asm/microcode.h | 2 ++ arch/x86/kernel/cpu/microcode/core.c | 6 +++--- arch/x86/power/cpu.c | 10 +++++++++- 3 files changed, 14 insertions(+), 4 deletions(-) diff --git a/arch/x86/include/asm/microcode.h b/arch/x86/include/asm/microcode.h index d6bfdfb..0c3d344 100644 --- a/arch/x86/include/asm/microcode.h +++ b/arch/x86/include/asm/microcode.h @@ -131,10 +131,12 @@ extern void __init load_ucode_bsp(void); extern void load_ucode_ap(void); void reload_early_microcode(void); extern bool initrd_gone; +void microcode_bsp_resume(void); #else static inline void __init load_ucode_bsp(void) { } static inline void load_ucode_ap(void) { } static inline void reload_early_microcode(void) { } +static inline void microcode_bsp_resume(void) { } #endif #endif /* _ASM_X86_MICROCODE_H */ diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c index f955d25..239ff5f 100644 --- a/arch/x86/kernel/cpu/microcode/core.c +++ b/arch/x86/kernel/cpu/microcode/core.c @@ -758,9 +758,9 @@ static struct subsys_interface mc_cpu_interface = { }; /** - * mc_bp_resume - Update boot CPU microcode during resume. + * microcode_bsp_resume - Update boot CPU microcode during resume. */ -static void mc_bp_resume(void) +void microcode_bsp_resume(void) { int cpu = smp_processor_id(); struct ucode_cpu_info *uci = ucode_cpu_info + cpu; @@ -772,7 +772,7 @@ static void mc_bp_resume(void) } static struct syscore_ops mc_syscore_ops = { - .resume = mc_bp_resume, + .resume = microcode_bsp_resume, }; static int mc_cpu_starting(unsigned int cpu) diff --git a/arch/x86/power/cpu.c b/arch/x86/power/cpu.c index 3822666..bb176c7 100644 --- a/arch/x86/power/cpu.c +++ b/arch/x86/power/cpu.c @@ -25,6 +25,7 @@ #include <asm/cpu.h> #include <asm/mmu_context.h> #include <asm/cpu_device_id.h> +#include <asm/microcode.h> #ifdef CONFIG_X86_32 __visible unsigned long saved_context_ebx; @@ -262,11 +263,18 @@ static void notrace __restore_processor_state(struct saved_context *ctxt) x86_platform.restore_sched_clock_state(); mtrr_bp_restore(); perf_restore_debug_store(); - msr_restore_context(ctxt); c = &cpu_data(smp_processor_id()); if (cpu_has(c, X86_FEATURE_MSR_IA32_FEAT_CTL)) init_ia32_feat_ctl(c); + + microcode_bsp_resume(); + + /* + * This needs to happen after the microcode has been updated upon resume + * because some of the MSRs are "emulated" in microcode. + */ + msr_restore_context(ctxt); } /* Needed by apm.c */
