Re: [PATCH v4 1/3] hyperv: Add definitions for MSHV sleep state configuration

Praveen Paladugu
2025-11-17T21:10:38Z

On Thu, Nov 13, 2025 at 07:41:55PM +0000, Michael Kelley wrote:
> From: Praveen K Paladugu <prapal@linux.microsoft.com> Sent: Friday, November 7, 2025 2:17 PM
> >
> > Add the definitions required to configure sleep states in mshv hypervsior.
> >
> > 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>
> > Reviewed-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
> > ---
> > include/hyperv/hvgdk_mini.h | 4 +++-
> > include/hyperv/hvhdk_mini.h | 33 +++++++++++++++++++++++++++++++++
> > 2 files changed, 36 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/hyperv/hvgdk_mini.h b/include/hyperv/hvgdk_mini.h
> > index 7499a679e60a..b43fa1c9ed2c 100644
> > --- a/include/hyperv/hvgdk_mini.h
> > +++ b/include/hyperv/hvgdk_mini.h
> > @@ -465,19 +465,21 @@ union hv_vp_assist_msr_contents { /*
> > HV_REGISTER_VP_ASSIST_PAGE */
> > #define HVCALL_RESET_DEBUG_SESSION 0x006b
> > #define HVCALL_MAP_STATS_PAGE 0x006c
> > #define HVCALL_UNMAP_STATS_PAGE 0x006d
> > +#define HVCALL_SET_SYSTEM_PROPERTY 0x006f
> > #define HVCALL_ADD_LOGICAL_PROCESSOR 0x0076
> > #define HVCALL_GET_SYSTEM_PROPERTY 0x007b
> > #define HVCALL_MAP_DEVICE_INTERRUPT 0x007c
> > #define HVCALL_UNMAP_DEVICE_INTERRUPT 0x007d
> > #define HVCALL_RETARGET_INTERRUPT 0x007e
> > #define HVCALL_NOTIFY_PARTITION_EVENT 0x0087
> > +#define HVCALL_ENTER_SLEEP_STATE 0x0084
> > #define HVCALL_NOTIFY_PORT_RING_EMPTY 0x008b
> > #define HVCALL_REGISTER_INTERCEPT_RESULT 0x0091
> > #define HVCALL_ASSERT_VIRTUAL_INTERRUPT 0x0094
> > #define HVCALL_CREATE_PORT 0x0095
> > #define HVCALL_CONNECT_PORT 0x0096
> > #define HVCALL_START_VP 0x0099
> > -#define HVCALL_GET_VP_INDEX_FROM_APIC_ID 0x009a
> > +#define HVCALL_GET_VP_INDEX_FROM_APIC_ID 0x009a
> > #define HVCALL_FLUSH_GUEST_PHYSICAL_ADDRESS_SPACE 0x00af
> > #define HVCALL_FLUSH_GUEST_PHYSICAL_ADDRESS_LIST 0x00b0
> > #define HVCALL_SIGNAL_EVENT_DIRECT 0x00c0
> > diff --git a/include/hyperv/hvhdk_mini.h b/include/hyperv/hvhdk_mini.h
> > index f2d7b50de7a4..06cf30deb319 100644
> > --- a/include/hyperv/hvhdk_mini.h
> > +++ b/include/hyperv/hvhdk_mini.h
> > @@ -140,6 +140,7 @@ enum hv_snp_status {
> >
> > enum hv_system_property {
> > /* Add more values when needed */
> > + HV_SYSTEM_PROPERTY_SLEEP_STATE = 3,
> > HV_SYSTEM_PROPERTY_SCHEDULER_TYPE = 15,
> > HV_DYNAMIC_PROCESSOR_FEATURE_PROPERTY = 21,
> > HV_SYSTEM_PROPERTY_CRASHDUMPAREA = 47,
> > @@ -155,6 +156,19 @@ union hv_pfn_range { /* HV_SPA_PAGE_RANGE */
> > } __packed;
> > };
> >
> > +enum hv_sleep_state {
> > + HV_SLEEP_STATE_S1 = 1,
> > + HV_SLEEP_STATE_S2 = 2,
> > + HV_SLEEP_STATE_S3 = 3,
> > + HV_SLEEP_STATE_S4 = 4,
> > + HV_SLEEP_STATE_S5 = 5,
> > + /*
> > + * After hypervisor has received this, any follow up sleep
> > + * state registration requests will be rejected.
> > + */
> > + HV_SLEEP_STATE_LOCK = 6
> > +};
> > +
> > enum hv_dynamic_processor_feature_property {
> > /* Add more values when needed */
> > HV_X64_DYNAMIC_PROCESSOR_FEATURE_MAX_ENCRYPTED_PARTITIONS =
> > 13,
> > @@ -184,6 +198,25 @@ struct hv_output_get_system_property {
> > };
> > } __packed;
> >
> > +struct hv_sleep_state_info {
> > + u32 sleep_state; /* enum hv_sleep_state */
> > + u8 pm1a_slp_typ;
> > + u8 pm1b_slp_typ;
> > +} __packed;
> > +
> > +struct hv_input_set_system_property {
> > + u32 property_id; /* enum hv_system_property */
> > + u32 reserved;
> > + union {
> > + /* More fields to be filled in when needed */
> > + struct hv_sleep_state_info set_sleep_state_info;
> > + };
> > +} __packed;
>
> Because struct hv_sleep_state_info is 6 bytes long, this
> hypercall input struct ends up being 14 bytes long, which is
> unusual. Hyper-V almost always makes hypercall input size
> a multiple of 8 bytes, though in a few cases the last 4 bytes
> might be ignored, making it a multiple of 4 bytes. So I'm
> wondering if there should be a 2 byte "reserved" field in
> struct hv_sleep_state_info so that everything ends up
> being a multiple of 8 bytes.
>
> Since there aren't any fields after such a putative "reserved"
> field, there's nothing currently at the wrong offset. But it would
> affect how much space gets zero'ed in hv_initialize_sleep_states().
> Zero'ing those last 2 bytes might prove useful if future versions
> of the hypervisor were to use those 2 bytes for an additional
> field or two.
>
Nice catch Michael. I added a reserved field to the union to keep the struct
fully aligned and future proof.

> > +
> > +struct hv_input_enter_sleep_state { /* HV_INPUT_ENTER_SLEEP_STATE */
> > + u32 sleep_state; /* enum hv_sleep_state */
> > +} __packed;
> > +
> > struct hv_input_map_stats_page {
> > u32 type; /* enum hv_stats_object_type */
> > u32 padding;
> > --
> > 2.51.0