On Thu, Nov 13, 2025 at 07:42:10PM +0000, Michael Kelley wrote: > From: Praveen K Paladugu <[email protected]> > > > > When a root partition running on MSHV is powered off, the default > > behavior is to write ACPI registers to power-off. However, this ACPI > > write is intercepted by MSHV and will result in a Machine Check > > Exception(MCE). > > > > The root partition eventually panics 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 correctly shutdown a root partition running on MSHV, sleep state > > information has be configured within mshv. Later HVCALL_ENTER_SLEEP_STATE > > s/has be/has to be/ --or-- s/has be/must be/ > > Nit: Be consistent in capitalizing "MSHV" (or not capitalizing it). > > > should be invoked as the last step in the shutdown sequence. > > > > The previous patch configures the sleep state information and this patch > > invokes HVCALL_ENTER_SLEEP_STATE to cleanly shutdown the root partition. > > > > Signed-off-by: Praveen K Paladugu <[email protected]> > > Co-developed-by: Anatol Belski <[email protected]> > > Signed-off-by: Anatol Belski <[email protected]> > > --- > > arch/x86/hyperv/hv_init.c | 2 ++ > > arch/x86/include/asm/mshyperv.h | 2 ++ > > drivers/hv/mshv_common.c | 19 +++++++++++++++++++ > > 3 files changed, 23 insertions(+) > > > > diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c > > index 645b52dd732e..24824534ff8d 100644 > > --- a/arch/x86/hyperv/hv_init.c > > +++ b/arch/x86/hyperv/hv_init.c > > @@ -34,6 +34,7 @@ > > #include <clocksource/hyperv_timer.h> > > #include <linux/highmem.h> > > #include <linux/export.h> > > +#include <asm/reboot.h> > > > > void *hv_hypercall_pg; > > > > @@ -562,6 +563,7 @@ void __init hyperv_init(void) > > * failures here. > > */ > > hv_sleep_notifiers_register(); > > + machine_ops.power_off = hv_machine_power_off; > > } else { > > hypercall_msr.guest_physical_address = > > vmalloc_to_pfn(hv_hypercall_pg); > > wrmsrq(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); > > diff --git a/arch/x86/include/asm/mshyperv.h > > b/arch/x86/include/asm/mshyperv.h > > index fbc1233175ce..9082d56103ce 100644 > > --- a/arch/x86/include/asm/mshyperv.h > > +++ b/arch/x86/include/asm/mshyperv.h > > @@ -182,9 +182,11 @@ void hv_apic_init(void); > > void __init hv_init_spinlocks(void); > > bool hv_vcpu_is_preempted(int vcpu); > > void hv_sleep_notifiers_register(void); > > +void hv_machine_power_off(void); > > #else > > static inline void hv_apic_init(void) {} > > static inline void hv_sleep_notifiers_register(void) {}; > > +static inline void hv_machine_power_off(void) {}; > > #endif > > > > struct irq_domain *hv_create_pci_msi_domain(void); > > diff --git a/drivers/hv/mshv_common.c b/drivers/hv/mshv_common.c > > index d1a1daa52b65..0588d293a92a 100644 > > --- a/drivers/hv/mshv_common.c > > +++ b/drivers/hv/mshv_common.c > > @@ -217,4 +217,23 @@ 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) > > +{ > > + u64 status; > > + 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; > > + > > + status = hv_do_hypercall(HVCALL_ENTER_SLEEP_STATE, in, NULL); > > As flagged by the kernel test robot, this should be > > (void)hv_do_hypercall(HVCALL_ENTER_SLEEP_STATE, in, NULL); > > so that the intent to ignore the return value is explicit. And the local > variable "status" can be removed. >
Thanks for the feedback. I addressed it in v5. > > + local_irq_restore(flags); > > + > > +} > > #endif > > -- > > 2.51.0
