x86/acpi/boot: Correct acpi_is_processor_usable() check

commit fed8d8773b8ea68ad99d9eee8c8343bef9da2c2c upstream.

The logic in acpi_is_processor_usable() requires the online capable
bit be set for hotpluggable CPUs.  The online capable bit has been
introduced in ACPI 6.3.

However, for ACPI revisions < 6.3 which do not support that bit, CPUs
should be reported as usable, not the other way around.

Reverse the check.

  [ bp: Rewrite commit message. ]

Fixes: e2869bd7af60 ("x86/acpi/boot: Do not register processors that cannot be onlined for x2APIC")
Suggested-by: Miguel Luis <miguel.luis@oracle.com>
Suggested-by: Boris Ostrovsky <boris.ovstrosky@oracle.com>
Signed-off-by: Eric DeVolder <eric.devolder@oracle.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Tested-by: David R <david@unsolicited.net>
Cc: <stable@kernel.org>
Link: https://lore.kernel.org/r/20230327191026.3454-2-eric.devolder@oracle.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 518bda5..ee45e0e 100644 (file)
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -193,7 +193,8 @@ static bool __init acpi_is_processor_usable(u32 lapic_flags)
        if (lapic_flags & ACPI_MADT_ENABLED)
                return true;
 
-       if (acpi_support_online_capable && (lapic_flags & ACPI_MADT_ONLINE_CAPABLE))
+       if (!acpi_support_online_capable ||
+           (lapic_flags & ACPI_MADT_ONLINE_CAPABLE))
                return true;
 
        return false;