linux-kernel - [PATCH v4 2/3] hyperv: Use reboot notifier to configure sleep state

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Message-ID: <20251107221700.45957-3-prapal@linux.microsoft.com>
Date: Fri,  7 Nov 2025 16:16:48 -0600
From: Praveen K Paladugu <prapal@...ux.microsoft.com>
To: kys@...rosoft.com,
	haiyangz@...rosoft.com,
	wei.liu@...nel.org,
	decui@...rosoft.com,
	tglx@...utronix.de,
	mingo@...hat.com,
	linux-hyperv@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	bp@...en8.de,
	dave.hansen@...ux.intel.com,
	x86@...nel.org,
	hpa@...or.com,
	arnd@...db.de
Cc: anbelski@...ux.microsoft.com,
	prapal@...ux.microsoft.com,
	easwar.hariharan@...ux.microsoft.com,
	nunodasneves@...ux.microsoft.com,
	skinsburskii@...ux.microsoft.com,
	mhklinux@...look.com
Subject: [PATCH v4 2/3] hyperv: Use reboot notifier to configure sleep state

Configure sleep state information in mshv hypervisor. This sleep state
information from ACPI will be used by hypervisor to poweroff the host.

Signed-off-by: Praveen K Paladugu <prapal@...ux.microsoft.com>
Co-developed-by: Anatol Belski <anbelski@...ux.microsoft.com>
Signed-off-by: Anatol Belski <anbelski@...ux.microsoft.com>
---
 arch/x86/hyperv/hv_init.c       |  7 +++
 arch/x86/include/asm/mshyperv.h |  2 +
 drivers/hv/mshv_common.c        | 80 +++++++++++++++++++++++++++++++++
 3 files changed, 89 insertions(+)

diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index e28737ec7054..645b52dd732e 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -555,6 +555,13 @@ void __init hyperv_init(void)
 
 		hv_remap_tsc_clocksource();
 		hv_root_crash_init();
+		/*
+		 * The notifier registration might fail at various hops.
+		 * Corresponding error messages will land in dmesg. There is
+		 * otherwise nothing that can be specifically done to handle
+		 * failures here.
+		 */
+		hv_sleep_notifiers_register();
 	} 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 1342d55c2545..fbc1233175ce 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -181,8 +181,10 @@ int hyperv_fill_flush_guest_mapping_list(
 void hv_apic_init(void);
 void __init hv_init_spinlocks(void);
 bool hv_vcpu_is_preempted(int vcpu);
+void hv_sleep_notifiers_register(void);
 #else
 static inline void hv_apic_init(void) {}
+static inline void hv_sleep_notifiers_register(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 aa2be51979fd..d1a1daa52b65 100644
--- a/drivers/hv/mshv_common.c
+++ b/drivers/hv/mshv_common.c
@@ -14,6 +14,9 @@
 #include <asm/mshyperv.h>
 #include <linux/resume_user_mode.h>
 #include <linux/export.h>
+#include <linux/acpi.h>
+#include <linux/notifier.h>
+#include <linux/reboot.h>
 
 #include "mshv.h"
 
@@ -138,3 +141,80 @@ int hv_call_get_partition_property(u64 partition_id,
 	return 0;
 }
 EXPORT_SYMBOL_GPL(hv_call_get_partition_property);
+
+#if IS_ENABLED(CONFIG_ACPI)
+/*
+ * Corresponding sleep states have to be initialized in order for a subsequent
+ * HVCALL_ENTER_SLEEP_STATE call to succeed. Currently only S5 state as per
+ * ACPI 6.4 chapter 7.4.2 is relevant, while S1, S2 and S3 can be supported.
+ *
+ * In order to pass proper PM values to mshv, ACPI should be initialized and
+ * should support S5 sleep state when this method is invoked.
+ */
+static int hv_initialize_sleep_states(void)
+{
+	u64 status;
+	unsigned long flags;
+	struct hv_input_set_system_property *in;
+	acpi_status acpi_status;
+	u8 sleep_type_a, sleep_type_b;
+
+	if (!acpi_sleep_state_supported(ACPI_STATE_S5)) {
+		pr_err("%s: S5 sleep state not supported.\n", __func__);
+		return -ENODEV;
+	}
+
+	acpi_status = acpi_get_sleep_type_data(ACPI_STATE_S5, &sleep_type_a,
+					       &sleep_type_b);
+	if (ACPI_FAILURE(acpi_status))
+		return -ENODEV;
+
+	local_irq_save(flags);
+	in = *this_cpu_ptr(hyperv_pcpu_input_arg);
+	memset(in, 0, sizeof(*in));
+
+	in->property_id = HV_SYSTEM_PROPERTY_SLEEP_STATE;
+	in->set_sleep_state_info.sleep_state = HV_SLEEP_STATE_S5;
+	in->set_sleep_state_info.pm1a_slp_typ = sleep_type_a;
+	in->set_sleep_state_info.pm1b_slp_typ = sleep_type_b;
+
+	status = hv_do_hypercall(HVCALL_SET_SYSTEM_PROPERTY, in, NULL);
+	local_irq_restore(flags);
+
+	if (!hv_result_success(status)) {
+		hv_status_err(status, "\n");
+		return hv_result_to_errno(status);
+	}
+
+	return 0;
+}
+
+/*
+ * This notifier initializes sleep states in mshv hypervisor which will be
+ * used during power off.
+ */
+static int hv_reboot_notifier_handler(struct notifier_block *this,
+				      unsigned long code, void *another)
+{
+	int ret = 0;
+
+	if (code == SYS_POWER_OFF)
+		ret = hv_initialize_sleep_states();
+
+	return ret ? NOTIFY_DONE : NOTIFY_OK;
+}
+
+static struct notifier_block hv_reboot_notifier = {
+	.notifier_call = hv_reboot_notifier_handler,
+};
+
+void hv_sleep_notifiers_register(void)
+{
+	int ret;
+
+	ret = register_reboot_notifier(&hv_reboot_notifier);
+	if (ret)
+		pr_err("%s: cannot register reboot notifier %d\n", __func__,
+		       ret);
+}
+#endif
-- 
2.51.0