6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Yuntao Wang yuntao.wang@linux.dev
commit 0ecc5be200c84e67114f3640064ba2bae3ba2f5a upstream.
x2apic_disable() clears x2apic_state and x2apic_mode unconditionally, even when the state is X2APIC_ON_LOCKED, which prevents the kernel to disable it thereby creating inconsistent state.
Due to the early state check for X2APIC_ON, the code path which warns about a locked X2APIC cannot be reached.
Test for state < X2APIC_ON instead and move the clearing of the state and mode variables to the place which actually disables X2APIC.
[ tglx: Massaged change log. Added Fixes tag. Moved clearing so it's at the right place for back ports ]
Fixes: a57e456a7b28 ("x86/apic: Fix fallout from x2apic cleanup") Signed-off-by: Yuntao Wang yuntao.wang@linux.dev Signed-off-by: Thomas Gleixner tglx@linutronix.de Cc: stable@vger.kernel.org Link: https://lore.kernel.org/all/20240813014827.895381-1-yuntao.wang@linux.dev Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kernel/apic/apic.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-)
--- a/arch/x86/kernel/apic/apic.c +++ b/arch/x86/kernel/apic/apic.c @@ -1812,12 +1812,9 @@ static __init void apic_set_fixmap(bool
static __init void x2apic_disable(void) { - u32 x2apic_id, state = x2apic_state; + u32 x2apic_id;
- x2apic_mode = 0; - x2apic_state = X2APIC_DISABLED; - - if (state != X2APIC_ON) + if (x2apic_state < X2APIC_ON) return;
x2apic_id = read_apic_id(); @@ -1830,6 +1827,10 @@ static __init void x2apic_disable(void) }
__x2apic_disable(); + + x2apic_mode = 0; + x2apic_state = X2APIC_DISABLED; + /* * Don't reread the APIC ID as it was already done from * check_x2apic() and the APIC driver still is a x2APIC variant,