The following commit has been merged into the x86/urgent branch of tip:
Commit-ID: 0ecc5be200c84e67114f3640064ba2bae3ba2f5a Gitweb: https://git.kernel.org/tip/0ecc5be200c84e67114f3640064ba2bae3ba2f5a Author: Yuntao Wang yuntao.wang@linux.dev AuthorDate: Tue, 13 Aug 2024 09:48:27 +08:00 Committer: Thomas Gleixner tglx@linutronix.de CommitterDate: Tue, 13 Aug 2024 15:15:19 +02:00
x86/apic: Make x2apic_disable() work correctly
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
--- arch/x86/kernel/apic/apic.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c index 66fd4b2..3736386 100644 --- a/arch/x86/kernel/apic/apic.c +++ b/arch/x86/kernel/apic/apic.c @@ -1775,12 +1775,9 @@ static __init void apic_set_fixmap(bool read_apic);
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(); @@ -1793,6 +1790,10 @@ 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,