mshv: Cleanly shutdown root partition with MSHV

Root partitions running on MSHV currently attempt ACPI power-off, which
MSHV intercepts and triggers a Machine Check Exception (MCE), leading
to a kernel panic.

Root partitions panic with a trace similar to:

  [   81.306348] reboot: Power down
  [   81.314709] mce: [Hardware Error]: CPU 0: Machine Check Exception: 4 Bank 0: b2000000c0060001
  [   81.314711] mce: [Hardware Error]: TSC 3b8cb60a66 PPIN 11d98332458e4ea9
  [   81.314713] mce: [Hardware Error]: PROCESSOR 0:606a6 TIME 1759339405 SOCKET 0 APIC 0 microcode ffffffff
  [   81.314715] mce: [Hardware Error]: Run the above through 'mcelog --ascii'
  [   81.314716] mce: [Hardware Error]: Machine check: Processor context corrupt
  [   81.314717] Kernel panic - not syncing: Fatal machine check

To avoid this, configure the sleep state in the hypervisor and invoke
the HVCALL_ENTER_SLEEP_STATE hypercall as the final step in the shutdown
sequence. This ensures a clean and safe shutdown of the root partition.

Signed-off-by: Praveen K Paladugu <prapal@linux.microsoft.com>
Co-developed-by: Anatol Belski <anbelski@linux.microsoft.com>
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Reviewed-by: Easwar Hariharan <easwar.hariharan@linux.microsoft.com>
Acked-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>

diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index 62a89debfbce45915e5f9e3884efb91569cacf40..eef4c3a5ba28ee13173ea649ae05c1d9a9e063ef 100644 (file)
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -178,6 +178,7 @@ int hyperv_fill_flush_guest_mapping_list(
                struct hv_guest_mapping_flush_list *flush,
                u64 start_gfn, u64 end_gfn);
 void hv_sleep_notifiers_register(void);
+void hv_machine_power_off(void);
 
 #ifdef CONFIG_X86_64
 void hv_apic_init(void);

diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index fac9953a72eff67b33e622de5abe813d099932bf..579fb2c64cfd46c08c59a2fae40815e8ff147ff5 100644 (file)
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -621,6 +621,8 @@ static void __init ms_hyperv_init_platform(void)
 #endif
 
 #if IS_ENABLED(CONFIG_HYPERV)
+       if (hv_root_partition())
+               machine_ops.power_off = hv_machine_power_off;
 #if defined(CONFIG_KEXEC_CORE)
        machine_ops.shutdown = hv_machine_shutdown;
 #endif

diff --git a/drivers/hv/mshv_common.c b/drivers/hv/mshv_common.c
index ee733ba1575e1aeb9bfbaadfec1ba3bea8adbe08..58027b23c206607d7aab4c9e199705aa61243eed 100644 (file)
--- a/drivers/hv/mshv_common.c
+++ b/drivers/hv/mshv_common.c
@@ -216,3 +216,24 @@ void hv_sleep_notifiers_register(void)
                pr_err("%s: cannot register reboot notifier %d\n", __func__,
                       ret);
 }
+
+/*
+ * Power off the machine by entering S5 sleep state via Hyper-V hypercall.
+ * This call does not return if successful.
+ */
+void hv_machine_power_off(void)
+{
+       unsigned long flags;
+       struct hv_input_enter_sleep_state *in;
+
+       local_irq_save(flags);
+       in = *this_cpu_ptr(hyperv_pcpu_input_arg);
+       in->sleep_state = HV_SLEEP_STATE_S5;
+
+       (void)hv_do_hypercall(HVCALL_ENTER_SLEEP_STATE, in, NULL);
+       local_irq_restore(flags);
+
+       /* should never reach here */
+       BUG();
+
+}