linux-kernel - [PATCH v2] x86/acpi: Preserve ACPI-table override during hibernation

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Date:   Tue, 29 Mar 2022 15:33:52 +0200
From:   Amadeusz Sławiński 
        <amadeuszx.slawinski@...ux.intel.com>
To:     x86@...nel.org, "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H . Peter Anvin" <hpa@...or.com>
Cc:     Cezary Rojewski <cezary.rojewski@...el.com>,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Amadeusz Sławiński 
        <amadeuszx.slawinski@...ux.intel.com>
Subject: [PATCH v2] x86/acpi: Preserve ACPI-table override during hibernation

When overriding NHLT ACPI-table tests show that on some platforms
there is problem that NHLT contains garbage after hibernation/resume
cycle.

Problem stems from the fact that ACPI override performs early memory
allocation using memblock_phys_alloc_range() in
memblock_phys_alloc_range(). This memory block is later being marked as
ACPI memory block in arch_reserve_mem_area(). Later when memory areas
are considered for hibernation it is being marked as nosave in
e820__register_nosave_regions().

Fix this by marking ACPI override memory area as ACPI NVS
(Non-Volatile-Sleeping), which according to specification needs to be
saved on entering S4 and restored when leaving and is implemented as
such in kernel.

Signed-off-by: Amadeusz Sławiński <amadeuszx.slawinski@...ux.intel.com>
---

Changes in v2:
 * Changed approach as method used in v1 introduced potential for memory
   corruption, which was caught by tests.
 * Adjusted commit message describing above change in approach.

---
 arch/x86/kernel/acpi/boot.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 0d01e7f5078c..2eeca97b730b 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -1772,7 +1772,7 @@ int __acpi_release_global_lock(unsigned int *lock)

 void __init arch_reserve_mem_area(acpi_physical_address addr, size_t size)
 {
-	e820__range_add(addr, size, E820_TYPE_ACPI);
+	e820__range_add(addr, size, E820_TYPE_NVS);
 	e820__update_table_print();
 }

-- 
2.25.1