linux-kernel - [PATCH v4] ACPI:PRM: Reduce unnecessary printing to avoid the worries of regular users

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Message-ID: <20250518062507.218855-1-qiyuzhu2@amd.com>
Date: Sun, 18 May 2025 06:25:07 +0000
From: Zhu Qiyu <qiyuzhu2@....com>
To: <rafael@...nel.org>
CC: <lenb@...nel.org>, <linux-acpi@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <qiyuzhu2@....com>
Subject: [PATCH v4] ACPI:PRM: Reduce unnecessary printing to avoid the worries of regular users

Commit 088984c8d54c ("ACPI: PRM: Find EFI_MEMORY_RUNTIME block for PRM
handler and context") introduces non-essential printing "Failed to find
VA for GUID: xxxx, PA: 0x0" which causes unnecessary worry for regular
users.

Refer to PRM Spec Section 4.1.2[1], both static data buffer address
and ACPI parameter buffer address may be NULL if they are not needed.
So there is no need to print out "Failed to find VA ... " to intimidate
regular users.

Link: https://uefi.org/sites/default/files/resources/Platform%20Runtime%20Mechanism%20-%20with%20legal%20notice.pdf # [1]

Signed-off-by: Zhu Qiyu <qiyuzhu2@....com>
---

Previous versions can be found at:
v1: https://lore.kernel.org/linux-acpi/CAJZ5v0hv0WKd-SXFhUgYs-Zpc+-PsSNOBu0r7L5TzJWgddtsKA@mail.gmail.com/t/#u
v2: https://lore.kernel.org/linux-acpi/20250512010620.142155-1-qiyuzhu2@amd.com/#r
v3: https://lore.kernel.org/linux-acpi/20250512011833.142204-1-qiyuzhu2@amd.com/t/#u

Changes in v2:
 - Reduce the code changes.
Changes in v3:
 - Fixed title letters not showing.
Changes in v4:
 - Only print the necessary warnings.

 drivers/acpi/prmt.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/acpi/prmt.c b/drivers/acpi/prmt.c
index e549914a636c..bee450869cce 100644
--- a/drivers/acpi/prmt.c
+++ b/drivers/acpi/prmt.c
@@ -85,8 +85,6 @@ static u64 efi_pa_va_lookup(efi_guid_t *guid, u64 pa)
 		}
 	}
 
-	pr_warn("Failed to find VA for GUID: %pUL, PA: 0x%llx", guid, pa);
-
 	return 0;
 }
 
@@ -154,6 +152,15 @@ acpi_parse_prmt(union acpi_subtable_headers *header, const unsigned long end)
 		guid_copy(&th->guid, (guid_t *)handler_info->handler_guid);
 		th->handler_addr =
 			(void *)efi_pa_va_lookup(&th->guid, handler_info->handler_address);
+		/*
+		 * Refer to PRM Spec, both static data buffer address and
+		 * ACPI parameter buffer address may be NULL if they are not
+		 * needed. So there only print out warning if handler address
+		 * is zero.
+		 */
+		if (!th->handler_addr)
+			pr_warn("Failed to find VA for GUID: %pUL, PA: 0x%llx",
+				&th->guid, handler_info->handler_address);
 
 		th->static_data_buffer_addr =
 			efi_pa_va_lookup(&th->guid, handler_info->static_data_buffer_address);

base-commit: 82f2b0b97b36ee3fcddf0f0780a9a0825d52fec3
-- 
2.43.0