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@oracle.com>
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: <stable@kernel.org>
Link: https://lore.kernel.org/r/943d2445-84df-d939-f578-5d8240d342cc@unsolicited.net

diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 1c38174..7292184 100644 (file)
--- 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,