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x86/apic: Make x2apic_disable() work correctly

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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: a57e456a7b ("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>
This commit is contained in:
Yuntao Wang
2024-08-13 09:48:27 +08:00
committed by Greg Kroah-Hartman
parent 55c834bc9f
commit 73d20d08d3
1 changed files with 6 additions and 5 deletions
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11
arch/x86/kernel/apic/apic.c
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@@ -1812,12 +1812,9 @@ 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();
@@ -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,