x86/acpi/boot: Correct acpi_is_processor_usable() check

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: e2869bd ("x86/acpi/boot: Do not register processors that cannot be onlined for x2APIC")
Suggested-by: Miguel Luis <[email protected]>
Suggested-by: Boris Ostrovsky <[email protected]>
Signed-off-by: Eric DeVolder <[email protected]>
Signed-off-by: Borislav Petkov (AMD) <[email protected]>
Tested-by: David R <[email protected]>
Cc: <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: Eric DeVolder

arch/x86/kernel/acpi/boot.c

@@ -197,7 +197,8 @@ 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;