Commit 0ecc5be2 authored by Yuntao Wang's avatar Yuntao Wang Committed by Thomas Gleixner
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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: a57e456a ("x86/apic: Fix fallout from x2apic cleanup")
Signed-off-by: default avatarYuntao Wang <yuntao.wang@linux.dev>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20240813014827.895381-1-yuntao.wang@linux.dev
parent 7c626ce4

arch/x86/kernel/apic/apic.c

+6 −5
Original line number Diff line number Diff line
@@ -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,