From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oi1-f199.google.com (mail-oi1-f199.google.com [209.85.167.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 887022571DA for ; Sun, 12 Jul 2026 04:36:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783830992; cv=none; b=mjoZ+ZRdrhLfzSfKbNMhajswAx+gD0sJcijq5/Wl4O+Ft4ZmzHLkfCB+a6ZQW5dw1+SbSDLT75az5JeBRAypKFuIvfLXT67AZaKI4NDHRWUPmVGuJYFE+3UKLPk6V5k8+5tSA/XAw8Nz81aV2rhE7m3WDkm5BivGG1imuVDOeCA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783830992; c=relaxed/simple; bh=vSC1xuOQAjZF6Jrq/+NUFCJjmL88JK5YjsCKR0LDG0k=; h=MIME-Version:Date:In-Reply-To:Message-ID:Subject:From:To: Content-Type; b=pU+GtalFKPrWgW83qtbbMORCiHHVtUhu020sd2peFWMwNbBUlF6IiUzzF/bgQXf3ncN1fXYQwLinor00YkyIeGoKNkmMQ27Dm9f86v9zzTeEu/A+gBYGw3kL3J0O4YdCjPjWW7nlRphV2PI2f2k+lu2+nS0cN8y/2Qocm1eQOKU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com; arc=none smtp.client-ip=209.85.167.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com Received: by mail-oi1-f199.google.com with SMTP id 5614622812f47-495f637105eso3642190b6e.2 for ; Sat, 11 Jul 2026 21:36:30 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1783830989; x=1784435789; h=content-type:to:from:subject:message-id:in-reply-to:date :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to:content-type; bh=uPbU9FlNGyF2cc+cyQWoygncFZlBQy2CRsK6JaaVcgw=; b=mFpgDO0bLANXJEF2bzBWmbbkU5Blc0Fu+qOsr8z4NJVMAEL7Cz6kFawXS2vWiisT6y FuqlG8/u58kh5htcQN4+iPTFHlZ0gKfhvI9czKJjBIg/gj+kZVTycGgKIDTtAkd4xujI qU7t4Hrmf1koknvQm6A9a8Gmu6qG7bXp5kLoklqRw2IN0mHK1qTAX414XMF4hQ8KK+Wv EFviJ83nWH+7pM8BCUJaTk/newsBV1Q0qrDR5l13hj9hp09yzThObp+vL7fZPsMV3i8+ vtRDI3ypYhkwyQlMr48JPe4TBDXvUMLmEtoJz1tollQjE+HiHyr5AvmlZ3ePkanS2tvq QMig== X-Gm-Message-State: AOJu0YwWBtzyVsL2Lb2tp28tUdX9L3Z8qPw/9Ucn1u3wKcS29+6nab8U kUhReAAtBLFw7pgDz6WASfb+wrCzzFnyW4Rob6qucvvkb4o4Yn8jEySdlImROrtdyGrsnUD07mY CqTxxylfgvfivRFKbygAwY+q/JFA/Kt7XuW7CAH8KZNu/1Ojwe89KhuSciYs= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6808:151e:b0:497:da47:df5f with SMTP id 5614622812f47-4a42acd4458mr3423158b6e.17.1783830989611; Sat, 11 Jul 2026 21:36:29 -0700 (PDT) Date: Sat, 11 Jul 2026 21:36:29 -0700 In-Reply-To: <6a4fcd58.a1ad617e.25832.000f.GAE@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a5319cd.63a5fcd8.28bd53.0012.GAE@google.com> Subject: Forwarded: [PATCH] KVM: x86: Add debug traces (KERN_WARNING) to investigate irq From: syzbot To: linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" For archival purposes, forwarding an incoming command email to linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com. *** Subject: [PATCH] KVM: x86: Add debug traces (KERN_WARNING) to investigate irq Author: kartikey406@gmail.com #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master Reported-by: syzbot+9dcd0a11dc9703a49511@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?extid=9dcd0a11dc9703a49511 Signed-off-by: Deepanshu Kartikey --- arch/x86/kvm/i8259.c | 37 ++++++++++++++++++++++++++++++++--- arch/x86/kvm/irq.c | 46 +++++++++++++++++++++++++++++++++++++++++--- 2 files changed, 77 insertions(+), 6 deletions(-) diff --git a/arch/x86/kvm/i8259.c b/arch/x86/kvm/i8259.c index 6a942ac622d5..20b3b4855974 100644 --- a/arch/x86/kvm/i8259.c +++ b/arch/x86/kvm/i8259.c @@ -233,13 +233,33 @@ int kvm_pic_read_irq(struct kvm *kvm) { int irq, irq2, intno; struct kvm_pic *s = kvm->arch.vpic; - - s->output = 0; - pic_lock(s); + printk(KERN_WARNING + "KVM_DEBUG: pic_read_irq START " + "output=%d " + "IRR0=%02x IMR0=%02x " + "ISR0=%02x\n", + s->output, + s->pics[0].irr, + s->pics[0].imr, + s->pics[0].isr); + s->output = 0; + printk(KERN_WARNING + "KVM_DEBUG: output set to 0!\n"); irq = pic_get_irq(&s->pics[0]); + printk(KERN_WARNING + "KVM_DEBUG: pic_get_irq returned %d\n", + irq); if (irq >= 0) { pic_intack(&s->pics[0], irq); + printk(KERN_WARNING + "KVM_DEBUG: after pic_intack " + "IRR0=%02x " + "ISR0=%02x " + "auto_eoi=%d\n", + s->pics[0].irr, + s->pics[0].isr, + s->pics[0].auto_eoi); if (irq == 2) { irq2 = pic_get_irq(&s->pics[1]); if (irq2 >= 0) @@ -253,6 +273,9 @@ int kvm_pic_read_irq(struct kvm *kvm) } else intno = s->pics[0].irq_base + irq; } else { + printk(KERN_WARNING + "KVM_DEBUG: spurious IRQ! " + "no irq found in IRR!\n"); /* * spurious IRQ on host controller */ @@ -260,6 +283,14 @@ int kvm_pic_read_irq(struct kvm *kvm) intno = s->pics[0].irq_base + irq; } pic_update_irq(s); + printk(KERN_WARNING + "KVM_DEBUG: pic_read_irq END " + "intno=%d " + "output=%d " + "IRR0=%02x\n", + intno, + s->output, + s->pics[0].irr); pic_unlock(s); return intno; diff --git a/arch/x86/kvm/irq.c b/arch/x86/kvm/irq.c index 8c62c6d4d5c1..0dad5d3c5413 100644 --- a/arch/x86/kvm/irq.c +++ b/arch/x86/kvm/irq.c @@ -79,8 +79,19 @@ int kvm_cpu_has_extint(struct kvm_vcpu *v) return 0; #ifdef CONFIG_KVM_IOAPIC - if (pic_in_kernel(v->kvm)) + if (pic_in_kernel(v->kvm)) { + printk(KERN_WARNING + "KVM_DEBUG: has_extint called " + "output=%d " + "IRR0=%02x IRR1=%02x " + "IMR0=%02x IMR1=%02x\n", + v->kvm->arch.vpic->output, + v->kvm->arch.vpic->pics[0].irr, + v->kvm->arch.vpic->pics[1].irr, + v->kvm->arch.vpic->pics[0].imr, + v->kvm->arch.vpic->pics[1].imr); return v->kvm->arch.vpic->output; + } #endif WARN_ON_ONCE(!irqchip_split(v->kvm)); @@ -127,7 +138,24 @@ EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_cpu_has_interrupt); */ int kvm_cpu_get_extint(struct kvm_vcpu *v) { + int result; + if (pic_in_kernel(v->kvm)) + printk(KERN_WARNING + "KVM_DEBUG: get_extint called " + "output=%d\n", + v->kvm->arch.vpic->output); if (!kvm_cpu_has_extint(v)) { + if (pic_in_kernel(v->kvm)) { + printk(KERN_WARNING + "KVM_DEBUG: has_extint=FALSE " + "returning -1! " + "output=%d\n", + v->kvm->arch.vpic->output); + } + else + printk(KERN_WARNING + "KVM_DEBUG: has_extint=FALSE " + "no pic in kernel!\n"); WARN_ON(!lapic_in_kernel(v)); return -1; } @@ -141,8 +169,20 @@ int kvm_cpu_get_extint(struct kvm_vcpu *v) #endif #ifdef CONFIG_KVM_IOAPIC - if (pic_in_kernel(v->kvm)) - return kvm_pic_read_irq(v->kvm); /* PIC */ + if (pic_in_kernel(v->kvm)) { + printk(KERN_WARNING + "KVM_DEBUG: calling pic_read_irq " + "output=%d\n", + v->kvm->arch.vpic->output); + result = kvm_pic_read_irq(v->kvm); + printk(KERN_WARNING + "KVM_DEBUG: pic_read_irq returned " + "intno=%d " + "output=%d\n", + result, + v->kvm->arch.vpic->output); + return result; /* PIC */ + } #endif WARN_ON_ONCE(!irqchip_split(v->kvm)); -- 2.43.0