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From: Thomas Gleixner <tglx@linutronix.de>
To: Vitaly Kuznetsov <vkuznets@redhat.com>, x86@kernel.org
Cc: Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH RFC 1/2] x86/apic: Do not make an exception for PIC_CASCADE_IR when marking legacy irqs in irq_matrix
Date: Thu, 18 Mar 2021 11:10:07 +0100	[thread overview]
Message-ID: <87tup8wz5s.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <87blbg7tlo.fsf@vitty.brq.redhat.com>

On Thu, Mar 18 2021 at 09:29, Vitaly Kuznetsov wrote:
> Thomas Gleixner <tglx@linutronix.de> writes:
>> Out of paranoia I'd rather ignore that IO/APIC pin completely if it
>> claims to be IRQ2. I assume there is no device connected to it at all,
>> right?
>
> The original issue was observed on Amazon's r5d.xlarge instance
> type. Your assumption seems to be correct, I don't see any device on
> IRQ2.
>
>>
>> Can you please provide a dmesg with apic=verbose on the command line?
>>
>
> Here you go, attached.

> [    0.931305] init IO_APIC IRQs
> [    0.931312] IOAPIC[0]: Preconfigured routing entry (0-0 -> IRQ 0 Level:0 ActiveLow:0)
> [    0.931316] IOAPIC[0]: Preconfigured routing entry (0-1 -> IRQ 1 Level:0 ActiveLow:0)

There you go:

> [    0.931320] IOAPIC[0]: Preconfigured routing entry (0-2 -> IRQ 2 Level:0 ActiveLow:0)

Yet another virtualization feature :)

Thanks,

        tglx


  reply	other threads:[~2021-03-18 10:10 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-19 11:30 [PATCH RFC 0/2] x86/apic: Avoid cm->allocated going negative in irq_matrix Vitaly Kuznetsov
2021-02-19 11:31 ` [PATCH RFC 1/2] x86/apic: Do not make an exception for PIC_CASCADE_IR when marking legacy irqs " Vitaly Kuznetsov
2021-03-17 20:14   ` Thomas Gleixner
2021-03-17 21:18     ` Thomas Gleixner
2021-03-17 21:40       ` Thomas Gleixner
2021-03-17 22:52         ` Thomas Gleixner
2021-03-18  8:47           ` Vitaly Kuznetsov
2021-03-18  8:29     ` Vitaly Kuznetsov
2021-03-18 10:10       ` Thomas Gleixner [this message]
2021-02-19 11:31 ` [PATCH RFC 2/2] genirq/matrix: WARN_ON_ONCE() when cm->allocated/m->total_allocated go negative Vitaly Kuznetsov
2021-03-17 20:38   ` Thomas Gleixner
2021-03-18  7:58     ` Vitaly Kuznetsov
2021-03-18 19:29       ` Thomas Gleixner
2021-03-19  9:59         ` Vitaly Kuznetsov
2021-03-11 10:19 ` [PATCH RFC 0/2] x86/apic: Avoid cm->allocated going negative in irq_matrix Vitaly Kuznetsov

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