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From: "H. Peter Anvin" <hpa@zytor.com>
To: Ingo Molnar <mingo@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Borislav Petkov <bp@alien8.de>, Andy Lutomirski <luto@kernel.org>
Cc: Steve Wahl <steve.wahl@hpe.com>,
	Mike Travis <mike.travis@hpe.com>,
	Dimitri Sivanich <dimitri.sivanich@hpe.com>,
	Russ Anderson <russ.anderson@hpe.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	"H. Peter Anvin (Intel)" <hpa@zytor.com>
Subject: [PATCH 5/6] x86/irq: WARN_ONCE() if irq_move_cleanup is called on a pending interrupt
Date: Mon, 10 May 2021 17:55:30 -0700	[thread overview]
Message-ID: <20210511005531.1065536-6-hpa@zytor.com> (raw)
In-Reply-To: <20210511005531.1065536-1-hpa@zytor.com>

From: "H. Peter Anvin (Intel)" <hpa@zytor.com>

The current IRQ vector allocation code should be "clean" and never
issue a IRQ_MOVE_CLEANUP_VECTOR IPI for an interrupt that could still
be pending. This should make it possible to move it to the "normal"
system IRQ vector range. This should probably be a three-step process:

1. Introduce this WARN_ONCE() on this event ever occurring.
2. Move the IRQ_MOVE_CLEANUP_VECTOR to the sysvec range.
3. Remove the self-IPI hack.

This implements step 1.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
---
 arch/x86/kernel/apic/vector.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c
index 6dbdc7c22bb7..7ba2982a3585 100644
--- a/arch/x86/kernel/apic/vector.c
+++ b/arch/x86/kernel/apic/vector.c
@@ -939,9 +939,14 @@ DEFINE_IDTENTRY_SYSVEC(sysvec_irq_move_cleanup)
 		 * to this CPU. IRQ_MOVE_CLEANUP_VECTOR is the lowest
 		 * priority external vector, so on return from this
 		 * interrupt the device interrupt will happen first.
+		 *
+		 * *** This should never happen with the current IRQ
+		 * cleanup code, so WARN_ONCE() for now, and
+		 * eventually get rid of this hack.
 		 */
 		irr = apic_read(APIC_IRR + (vector / 32 * 0x10));
 		if (irr & (1U << (vector % 32))) {
+			WARN_ONCE(1, "irq_move_cleanup called on still pending interrupt\n");
 			apic->send_IPI_self(IRQ_MOVE_CLEANUP_VECTOR);
 			continue;
 		}
-- 
2.31.1


  parent reply	other threads:[~2021-05-11  0:56 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-11  0:55 [PATCH 0/6] x86/irq: trap and interrupt cleanups H. Peter Anvin
2021-05-11  0:55 ` [PATCH 1/6] x86/traps: add X86_NR_HW_TRAPS to <asm/trapnr.h> H. Peter Anvin
2021-05-14 22:53   ` Andy Lutomirski
2021-05-11  0:55 ` [PATCH 2/6] x86/irqvector: add NR_EXTERNAL_VECTORS and NR_SYSTEM_VECTORS H. Peter Anvin
2021-05-14 22:53   ` Andy Lutomirski
2021-05-11  0:55 ` [PATCH 3/6] x86/idt: remove address argument to idt_invalidate() H. Peter Anvin
2021-05-11  4:37   ` kernel test robot
2021-05-11 14:14   ` Thomas Gleixner
2021-05-11 14:43     ` H. Peter Anvin
2021-05-11  0:55 ` [PATCH 4/6] x86/irq: merge common code in DEFINE_IDTENTRY_SYSVEC[_SIMPLE] H. Peter Anvin
2021-05-11 14:22   ` Thomas Gleixner
2021-05-11 17:44     ` H. Peter Anvin
2021-05-12  8:38       ` Ingo Molnar
2021-05-12 18:00         ` H. Peter Anvin
2021-05-12 18:40           ` Ingo Molnar
2021-05-11  0:55 ` H. Peter Anvin [this message]
2021-05-11 14:23   ` [PATCH 5/6] x86/irq: WARN_ONCE() if irq_move_cleanup is called on a pending interrupt Thomas Gleixner
2021-05-11 15:55     ` H. Peter Anvin
2021-05-11  0:55 ` [PATCH 6/6] x86/irq: remove unused vectors from <asm/irq_vectors.h> H. Peter Anvin
2021-05-11 17:04   ` Steve Wahl

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