From nobody Sun Oct 5 14:34:06 2025 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5701D2AD11; Sat, 2 Aug 2025 20:08:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754165339; cv=none; b=i8C+BMrG5qj6LiBPfiKf7IgWE4KgEc6NHgSN+ulcWG5upTRhaGZaAV2CSPk0nzTryBVjfS0c48Nn0Ib1lBDneUylvUwE6mg6jJ6uh/FgjfJYnNUPMqYiPpYKv31CMynNnbAPb3/vdN4+twAfyANltLq6LfPISrKJ2rBXiHxysnk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754165339; c=relaxed/simple; bh=6vS51PCfgbmzP1UTqjLpQ6KW9OVizJL54e8eUStnV3o=; h=Date:From:To:Subject:Cc:In-Reply-To:References:MIME-Version: Message-ID:Content-Type; b=kiI8yElkaUa32TtxQ+6pYZQ3RTRxakWxd3MDqwzD6JDJgSasKiGWnG8fOkoWs9hGsXROtHA7saFMt8NxW8MFNkSkXGL22xslXsw0SnSo5MOVYkrKB7ruRI3CRC27kqG/ztxyzYKDDda1k0dDLC6KNhgoYDuL0EUjweDzQqMXGNg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=Ty70C0q9; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=T/xqubiA; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="Ty70C0q9"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="T/xqubiA" Date: Sat, 02 Aug 2025 20:08:53 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1754165335; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=YjDCYU43xkWZRM0jTG9QW/sOVarVHPFGlSm9G3Pq0q0=; b=Ty70C0q9pn+xbpN0UkY64kMp6TwdjmUcRUx+cm2ZVdBqYXN46i0wbGBCXgMfTBKkg/d9ap sJrkzFFOmWBUOxBHQTFVVHoOVMh/Yu9BAogrqix3af/5WgcLlSI8HqGHmDLy4iIX2wvCF0 rm+Z/Wk6BGFTP8LWo+T0K3Vh7uvLMKonbi5VI2MV+Ax67ZaGKXEfzSeM7kME1h/3gJvOtC etF9JLfz2y1Km6LmpQ0mgG/S9hEfguft4vDswpQ2/+H9CTfZCdCE3iFN5/rEwFtmPVwkzw plu5yJHwDArYzN9/o38HpBr/bhpYVtT51bccncdilWJFHTOdqG/2aswG7gs9kw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1754165335; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=YjDCYU43xkWZRM0jTG9QW/sOVarVHPFGlSm9G3Pq0q0=; b=T/xqubiALIkR7ApHhUa45kTI0Oy3rXRgkIC3YthWWSmvB1PidAZtzVYUgwfXk+jcoFn8En 2Dd2gCQepTMXv6AQ== From: "tip-bot2 for Thomas Gleixner" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/urgent] x86/irq: Plug vector setup race Cc: Hogan Wang , Thomas Gleixner , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-ID: <175416533376.1420.15851948598684111858.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Precedence: bulk Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable The following commit has been merged into the x86/urgent branch of tip: Commit-ID: e3079ac6cf4213dd46a7a292150b2ba7e6e85bac Gitweb: https://git.kernel.org/tip/e3079ac6cf4213dd46a7a292150b2ba7e= 6e85bac Author: Thomas Gleixner AuthorDate: Thu, 24 Jul 2025 12:49:30 +02:00 Committer: Thomas Gleixner CommitterDate: Sat, 02 Aug 2025 21:56:35 +02:00 x86/irq: Plug vector setup race Hogan reported a vector setup race, which overwrites the interrupt descriptor in the per CPU vector array resulting in a disfunctional device. CPU0 CPU1 interrupt is raised in APIC IRR but not handled free_irq() per_cpu(vector_irq, CPU1)[vector] =3D VECTOR_SHUTDOWN; request_irq() common_interrupt() d =3D this_cpu_read(vector_irq[vector]); per_cpu(vector_irq, CPU1)[vector] =3D desc; if (d =3D=3D VECTOR_SHUTDOWN) this_cpu_write(vector_irq[vector], VECTOR_UNUSED); free_irq() cannot observe the pending vector in the CPU1 APIC as there is no way to query the remote CPUs APIC IRR. This requires that request_irq() uses the same vector/CPU as the one which was freed, but this also can be triggered by a spurious interrupt. Interestingly enough this problem managed to be hidden for more than a decade. Prevent this by reevaluating vector_irq under the vector lock, which is held by the interrupt activation code when vector_irq is updated. To avoid ifdeffery or IS_ENABLED() nonsense, repair the broken config dependency in hw_irq.h, which covers [un]lock_vector_lock(). It has to depend on CONFIG_X86_LOCAL_APIC as that's what makes the functions available or stubbed out. The current CONFIG_IRQ_DOMAIN_HIERARCHY guard is selected by CONFIG_X86_LOCAL_APIC, but can also be selected by other parts of the Kconfig system, which makes 32-bit UP builds with CONFIG_X86_LOCAL_APIC=3Dn fail. Can we just get rid of this !APIC nonsense once and forever? Fixes: 9345005f4eed ("x86/irq: Fix do_IRQ() interrupt warning for cpu hotpl= ug retriggered irqs") Reported-by: Hogan Wang Signed-off-by: Thomas Gleixner Tested-by: Hogan Wang Link: https://lore.kernel.org/all/draft-87ikjhrhhh.ffs@tglx --- arch/x86/include/asm/hw_irq.h | 6 +-- arch/x86/kernel/irq.c | 63 +++++++++++++++++++++++++--------- 2 files changed, 51 insertions(+), 18 deletions(-) diff --git a/arch/x86/include/asm/hw_irq.h b/arch/x86/include/asm/hw_irq.h index 162ebd7..99f7bf9 100644 --- a/arch/x86/include/asm/hw_irq.h +++ b/arch/x86/include/asm/hw_irq.h @@ -26,7 +26,7 @@ #include #include =20 -#ifdef CONFIG_IRQ_DOMAIN_HIERARCHY +#ifdef CONFIG_X86_LOCAL_APIC struct irq_data; struct pci_dev; struct msi_desc; @@ -103,10 +103,10 @@ static inline void irq_complete_move(struct irq_cfg *= c) { } #endif =20 extern void apic_ack_edge(struct irq_data *data); -#else /* CONFIG_IRQ_DOMAIN_HIERARCHY */ +#else /* CONFIG_X86_LOCAL_APIC */ static inline void lock_vector_lock(void) {} static inline void unlock_vector_lock(void) {} -#endif /* CONFIG_IRQ_DOMAIN_HIERARCHY */ +#endif /* !CONFIG_X86_LOCAL_APIC */ =20 /* Statistics */ extern atomic_t irq_err_count; diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c index 9ed29ff..10721a1 100644 --- a/arch/x86/kernel/irq.c +++ b/arch/x86/kernel/irq.c @@ -256,26 +256,59 @@ static __always_inline void handle_irq(struct irq_des= c *desc, __handle_irq(desc, regs); } =20 -static __always_inline int call_irq_handler(int vector, struct pt_regs *re= gs) +static struct irq_desc *reevaluate_vector(int vector) { - struct irq_desc *desc; - int ret =3D 0; + struct irq_desc *desc =3D __this_cpu_read(vector_irq[vector]); + + if (!IS_ERR_OR_NULL(desc)) + return desc; + + if (desc =3D=3D VECTOR_UNUSED) + pr_emerg_ratelimited("No irq handler for %d.%u\n", smp_processor_id(), v= ector); + else + __this_cpu_write(vector_irq[vector], VECTOR_UNUSED); + return NULL; +} + +static __always_inline bool call_irq_handler(int vector, struct pt_regs *r= egs) +{ + struct irq_desc *desc =3D __this_cpu_read(vector_irq[vector]); =20 - desc =3D __this_cpu_read(vector_irq[vector]); if (likely(!IS_ERR_OR_NULL(desc))) { handle_irq(desc, regs); - } else { - ret =3D -EINVAL; - if (desc =3D=3D VECTOR_UNUSED) { - pr_emerg_ratelimited("%s: %d.%u No irq handler for vector\n", - __func__, smp_processor_id(), - vector); - } else { - __this_cpu_write(vector_irq[vector], VECTOR_UNUSED); - } + return true; } =20 - return ret; + /* + * Reevaluate with vector_lock held to prevent a race against + * request_irq() setting up the vector: + * + * CPU0 CPU1 + * interrupt is raised in APIC IRR + * but not handled + * free_irq() + * per_cpu(vector_irq, CPU1)[vector] =3D VECTOR_SHUTDOWN; + * + * request_irq() common_interrupt() + * d =3D this_cpu_read(vector_irq[vector]); + * + * per_cpu(vector_irq, CPU1)[vector] =3D desc; + * + * if (d =3D=3D VECTOR_SHUTDOWN) + * this_cpu_write(vector_irq[vector], VECTOR_UNUSED); + * + * This requires that the same vector on the same target CPU is + * handed out or that a spurious interrupt hits that CPU/vector. + */ + lock_vector_lock(); + desc =3D reevaluate_vector(vector); + unlock_vector_lock(); + + if (!desc) + return false; + + handle_irq(desc, regs); + return true; } =20 /* @@ -289,7 +322,7 @@ DEFINE_IDTENTRY_IRQ(common_interrupt) /* entry code tells RCU that we're not quiescent. Check it. */ RCU_LOCKDEP_WARN(!rcu_is_watching(), "IRQ failed to wake up RCU"); =20 - if (unlikely(call_irq_handler(vector, regs))) + if (unlikely(!call_irq_handler(vector, regs))) apic_eoi(); =20 set_irq_regs(old_regs);