[tip: x86/urgent] x86/acpi/boot: Correct acpi_is_processor_usable() check

[tip-bot2 for Eric DeVolder]

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

Commit-ID:     fed8d8773b8ea68ad99d9eee8c8343bef9da2c2c
Gitweb:        https://git.kernel.org/tip/fed8d8773b8ea68ad99d9eee8c8343bef9da2c2c
Author:        Eric DeVolder <eric.devolder@xxxxxxxxxx>
AuthorDate:    Mon, 27 Mar 2023 15:10:26 -04:00
Committer:     Borislav Petkov (AMD) <bp@xxxxxxxxx>
CommitterDate: Thu, 30 Mar 2023 11:07:30 +02:00

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: e2869bd7af60 ("x86/acpi/boot: Do not register processors that cannot be onlined for x2APIC")
Suggested-by: Miguel Luis <miguel.luis@xxxxxxxxxx>
Suggested-by: Boris Ostrovsky <boris.ovstrosky@xxxxxxxxxx>
Signed-off-by: Eric DeVolder <eric.devolder@xxxxxxxxxx>
Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Tested-by: David R <david@xxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230327191026.3454-2-eric.devolder@xxxxxxxxxx
---
 arch/x86/kernel/acpi/boot.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 7292184..0dac4ab 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/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;