The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-4.19.y git checkout FETCH_HEAD git cherry-pick -x 0ecc5be200c84e67114f3640064ba2bae3ba2f5a # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024090830-reactive-jokester-6061@gregkh' --subject-prefix 'PATCH 4.19.y' HEAD^..
Possible dependencies:
0ecc5be200c8 ("x86/apic: Make x2apic_disable() work correctly") 720a22fd6c1c ("x86/apic: Don't access the APIC when disabling x2APIC") 5a88f354dcd8 ("x86/apic: Split register_apic_address()") d10a904435fa ("x86/apic: Consolidate boot_cpu_physical_apicid initialization sites") 49062454a3eb ("x86/apic: Rename disable_apic") bea629d57d00 ("x86/apic: Save the APIC virtual base address") 3adee777ad0d ("x86/smpboot: Remove initial_stack on 64-bit") 94a855111ed9 ("Merge tag 'x86_core_for_v6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip")
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 0ecc5be200c84e67114f3640064ba2bae3ba2f5a Mon Sep 17 00:00:00 2001 From: Yuntao Wang yuntao.wang@linux.dev Date: Tue, 13 Aug 2024 09:48:27 +0800 Subject: [PATCH] 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
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c index 66fd4b2a37a3..373638691cd4 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,