linux-kernel - [tip: x86/urgent] x86/ACPI/boot: Use FADT version to check support for online capable

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Message-ID: <168016878085.404.6003734700616193238.tip-bot2@tip-bot2>
Date:   Thu, 30 Mar 2023 09:33:00 -0000
From:   "tip-bot2 for Mario Limonciello" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Eric DeVolder <eric.devolder@...cle.com>,
        Borislav Petkov <bp@...en8.de>,
        Mario Limonciello <mario.limonciello@....com>,
        <stable@...nel.org>, x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [tip: x86/urgent] x86/ACPI/boot: Use FADT version to check support
 for online capable

The following commit has been merged into the x86/urgent branch of tip:

Commit-ID:     a74fabfbd1b7013045afc8cc541e6cab3360ccb5
Gitweb:        https://git.kernel.org/tip/a74fabfbd1b7013045afc8cc541e6cab3360ccb5
Author:        Mario Limonciello <mario.limonciello@....com>
AuthorDate:    Wed, 29 Mar 2023 12:45:35 -05:00
Committer:     Borislav Petkov (AMD) <bp@...en8.de>
CommitterDate: Thu, 30 Mar 2023 10:50:30 +02:00

x86/ACPI/boot: Use FADT version to check support for online capable

ACPI 6.3 introduced the online capable bit, and also introduced MADT
version 5.

Latter was used to distinguish whether the offset storing online capable
could be used. However ACPI 6.2b has MADT version "45" which is for
an errata version of the ACPI 6.2 spec.  This means that the Linux code
for detecting availability of MADT will mistakenly flag ACPI 6.2b as
supporting online capable which is inaccurate as it's an ACPI 6.3 feature.

Instead use the FADT major and minor revision fields to distinguish this.

  [ bp: Massage. ]

Fixes: aa06e20f1be6 ("x86/ACPI: Don't add CPUs that are not online capable")
Reported-by: Eric DeVolder <eric.devolder@...cle.com>
Reported-by: Borislav Petkov <bp@...en8.de>
Signed-off-by: Mario Limonciello <mario.limonciello@....com>
Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
Cc: <stable@...nel.org>
Link: https://lore.kernel.org/r/943d2445-84df-d939-f578-5d8240d342cc@unsolicited.net
---
 arch/x86/kernel/acpi/boot.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 1c38174..7292184 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -146,7 +146,11 @@ static int __init acpi_parse_madt(struct acpi_table_header *table)
 
 		pr_debug("Local APIC address 0x%08x\n", madt->address);
 	}
-	if (madt->header.revision >= 5)
+
+	/* ACPI 6.3 and newer support the online capable bit. */
+	if (acpi_gbl_FADT.header.revision > 6 ||
+	    (acpi_gbl_FADT.header.revision == 6 &&
+	     acpi_gbl_FADT.minor_revision >= 3))
 		acpi_support_online_capable = true;
 
 	default_acpi_madt_oem_check(madt->header.oem_id,