linux-kernel - [PATCH v7 7/9] x86/acpi: Add a helper get the address of the wakeup mailbox

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Message-Id: <20251117-rneri-wakeup-mailbox-v7-7-4a8b82ab7c2c@linux.intel.com>
Date: Mon, 17 Nov 2025 09:02:53 -0800
From: Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
To: x86@...nel.org, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, Rob Herring <robh@...nel.org>, 
 "K. Y. Srinivasan" <kys@...rosoft.com>, 
 Haiyang Zhang <haiyangz@...rosoft.com>, Wei Liu <wei.liu@...nel.org>, 
 Dexuan Cui <decui@...rosoft.com>, Michael Kelley <mhklinux@...look.com>, 
 "Rafael J. Wysocki" <rafael@...nel.org>
Cc: Saurabh Sengar <ssengar@...ux.microsoft.com>, 
 Chris Oo <cho@...rosoft.com>, "Kirill A. Shutemov" <kas@...nel.org>, 
 linux-hyperv@...r.kernel.org, devicetree@...r.kernel.org, 
 linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Ricardo Neri <ricardo.neri@...el.com>, 
 Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
Subject: [PATCH v7 7/9] x86/acpi: Add a helper get the address of the
 wakeup mailbox

A Hyper-V VTL level 2 guest in a TDX environment needs to map the physical
page of the ACPI Multiprocessor Wakeup Structure as private (encrypted). It
needs to know the physical address of this structure. Add a helper function
to retrieve the address.

Suggested-by: Michael Kelley <mhklinux@...look.com>
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
---
Changes in v7:
 - Moved the added function to arch/x86/kernel/acpi/madt_wakeup.c
 - Dropped Reviewed-by tags from Dexuan and Michael as this patch
   changed.

Changes in v6:
 - Added Reviewed-by tag from Dexuan. Thanks!

Changes in v5:
 - None

Changes in v4:
 - Renamed function to acpi_get_mp_wakeup_mailbox_paddr().
 - Added Reviewed-by tag from Michael. Thanks!

Changes in v3:
 - Introduced this patch

Changes in v2:
 - N/A
---
 arch/x86/include/asm/acpi.h        | 6 ++++++
 arch/x86/kernel/acpi/madt_wakeup.c | 5 +++++
 2 files changed, 11 insertions(+)

diff --git a/arch/x86/include/asm/acpi.h b/arch/x86/include/asm/acpi.h
index 820df375df79..c4e6459bd56b 100644
--- a/arch/x86/include/asm/acpi.h
+++ b/arch/x86/include/asm/acpi.h
@@ -184,6 +184,7 @@ void __iomem *x86_acpi_os_ioremap(acpi_physical_address phys, acpi_size size);

 void acpi_setup_mp_wakeup_mailbox(u64 addr);
 struct acpi_madt_multiproc_wakeup_mailbox *acpi_get_mp_wakeup_mailbox(void);
+u64 acpi_get_mp_wakeup_mailbox_paddr(void);

 #else /* !CONFIG_ACPI */

@@ -210,6 +211,11 @@ static inline struct acpi_madt_multiproc_wakeup_mailbox *acpi_get_mp_wakeup_mail
 	return NULL;
 }

+static inline u64 acpi_get_mp_wakeup_mailbox_paddr(void)
+{
+	return 0;
+}
+
 #endif /* !CONFIG_ACPI */

 #define ARCH_HAS_POWER_INIT	1
diff --git a/arch/x86/kernel/acpi/madt_wakeup.c b/arch/x86/kernel/acpi/madt_wakeup.c
index 82caf44b45e3..48734e4a6e8f 100644
--- a/arch/x86/kernel/acpi/madt_wakeup.c
+++ b/arch/x86/kernel/acpi/madt_wakeup.c
@@ -258,3 +258,8 @@ struct acpi_madt_multiproc_wakeup_mailbox *acpi_get_mp_wakeup_mailbox(void)
 {
 	return acpi_mp_wake_mailbox;
 }
+
+u64 acpi_get_mp_wakeup_mailbox_paddr(void)
+{
+	return acpi_mp_wake_mailbox_paddr;
+}

-- 
2.43.0