From: Borislav Petkov <[email protected]>
When resuming from system sleep state, restore_processor_state()
restores the boot CPU MSRs. These MSRs could be emulated by the
microcode. If microcode is not loaded yet, writing to emulated MSRs
leads to unchecked MSR access error:
[ 28.702947] PM: Calling lapic_suspend+0x0/0x210
[ 28.703345] unchecked MSR access error: WRMSR to 0x10f (tried to write 0=x0000000000000000) at rIP: 0xffffffff9b2819e4 (native_write_msr+0x4/0x20)
[ 28.703357] Call Trace:
[ 28.703359] <TASK>
[ 28.703361] ? restore_processor_state+0x255/0x2d0
[ 28.703369] x86_acpi_suspend_lowlevel+0x11f/0x170
[ 28.703374] acpi_suspend_enter+0x4f/0x1f0
[ 28.703379] suspend_devices_and_enter+0x6e0/0x7d0
[ 28.703384] pm_suspend.cold+0x35c/0x3a7
[ 28.703388] state_store+0x81/0xe0
[ 28.703392] kobj_attr_store+0x12/0x20
[ 28.703396] sysfs_kf_write+0x3f/0x50
[ 28.703399] kernfs_fop_write_iter+0x13b/0x1d0
[ 28.703403] new_sync_write+0x101/0x180
[ 28.703408] vfs_write+0x217/0x2a0
[ 28.703413] ksys_write+0x67/0xe0
[ 28.703417] __x64_sys_write+0x1a/0x20
[ 28.703421] do_syscall_64+0x3b/0x90
[ 28.703426] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 28.703429] RIP: 0033:0x7fda13c260a7
[ 28.703434] Code: 64 89 02 48 c7 c0 ff ff ff ff eb bb 0f 1f 80 00 00 00 =
00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 01 00 00 00 0f 05 <48=
> 3d 00 f0 ff ff 77 51 c3 48 83 ec 28 48 89 54 24 18 48 89 74 24
[ 28.703437] RSP: 002b:00007fffa4060268 EFLAGS: 00000246 ORIG_RAX: 000000=0000000001
[ 28.703441] RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00007fda13c=260a7
[ 28.703443] RDX: 0000000000000004 RSI: 000055a41f65a570 RDI: 00000000000=00004
[ 28.703444] RBP: 000055a41f65a570 R08: 0000000000000000 R09: 00000000000=00004
[ 28.703446] R10: 000055a41f0cc2a6 R11: 0000000000000246 R12: 00000000000=00004
[ 28.703447] R13: 000055a41f657510 R14: 00007fda13d014a0 R15: 00007fda13d=008a0
To ensure microcode emulated MSRs are available for restoration, load
the microcode for boot CPU before restoring these MSRs.
Reported-by: Kyle D. Pelton <[email protected]>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=215841
Fixes: e2a1256b17b1 ("x86/speculation: Restore speculation related MSRs during S3 resume")
Signed-off-by: Borislav Petkov <[email protected]>
Signed-off-by: Pawan Gupta <[email protected]>
Tested-by: Kyle D. Pelton <[email protected]>
Cc: [email protected]
---
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 d6bfdfb0f0af..0c3d3440fe27 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 f955d25076ba..239ff5fcec6a 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 3822666fb73d..bb176c72891c 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 */
--
2.35.1