From: Borislav Petkov bp@suse.de
commit f9e14dbbd454581061c736bf70bf5cbb15ac927c upstream.
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@intel.com Signed-off-by: Borislav Petkov bp@suse.de Signed-off-by: Pawan Gupta pawan.kumar.gupta@linux.intel.com Tested-by: Kyle D. Pelton kyle.d.pelton@intel.com Cc: stable@vger.kernel.org Link: https://bugzilla.kernel.org/show_bug.cgi?id=215841 Link: https://lore.kernel.org/r/4350dfbf785cd482d3fafa72b2b49c83102df3ce.165038631... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/include/asm/microcode.h | 2 ++ arch/x86/kernel/cpu/microcode/core.c | 6 +++--- arch/x86/power/cpu.c | 8 ++++++++ 3 files changed, 13 insertions(+), 3 deletions(-)
--- a/arch/x86/include/asm/microcode.h +++ b/arch/x86/include/asm/microcode.h @@ -133,11 +133,13 @@ extern void load_ucode_ap(void); void reload_early_microcode(void); extern bool get_builtin_firmware(struct cpio_data *cd, const char *name); extern bool initrd_gone; +void microcode_bsp_resume(void); #else static inline int __init microcode_init(void) { return 0; }; 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) { } static inline bool get_builtin_firmware(struct cpio_data *cd, const char *name) { return false; } #endif --- a/arch/x86/kernel/cpu/microcode/core.c +++ b/arch/x86/kernel/cpu/microcode/core.c @@ -773,9 +773,9 @@ static struct subsys_interface mc_cpu_in };
/** - * 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; @@ -787,7 +787,7 @@ 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) --- a/arch/x86/power/cpu.c +++ b/arch/x86/power/cpu.c @@ -26,6 +26,7 @@ #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; @@ -268,6 +269,13 @@ static void notrace __restore_processor_ x86_platform.restore_sched_clock_state(); mtrr_bp_restore(); perf_restore_debug_store(); + + 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); }