linux-kernel - Re: [patch V3 09/33] genirq/msi: Add range checking to msi_insert

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Message-ID: <87fsdgzpqs.ffs@tglx>
Date:   Thu, 15 Dec 2022 15:49:15 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Niklas Schnelle <schnelle@...ux.ibm.com>,
        Guenter Roeck <linux@...ck-us.net>
Cc:     LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
        Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        linux-pci@...r.kernel.org, Bjorn Helgaas <bhelgaas@...gle.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Marc Zyngier <maz@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jason Gunthorpe <jgg@...lanox.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Alex Williamson <alex.williamson@...hat.com>,
        Kevin Tian <kevin.tian@...el.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Logan Gunthorpe <logang@...tatee.com>,
        Ashok Raj <ashok.raj@...el.com>, Jon Mason <jdmason@...zu.us>,
        Allen Hubbe <allenbh@...il.com>,
        Matthew Rosato <mjrosato@...ux.ibm.com>
Subject: Re: [patch V3 09/33] genirq/msi: Add range checking to
 msi_insert_desc()

On Wed, Dec 14 2022 at 10:42, Niklas Schnelle wrote:
> On Tue, 2022-12-13 at 11:04 -0800, Guenter Roeck wrote:
>> This patch results in various s390 qemu test failures.
>> There is a warning backtrace
>> 
>>    12.674858] WARNING: CPU: 0 PID: 1 at kernel/irq/msi.c:167 msi_ctrl_valid+0x2a/0xb0
>> 
>> followed by
>> 
>> [   12.684333] virtio_net: probe of virtio0 failed with error -34
>> 
>> and Ethernet interfaces don't instantiate.
> As far as I'm aware so far he tracked this down to code calling
> msi_domain_get_hwsize() which in turn calls msi_get_device_domain()
> which then returns NULL leading to msi_domain_get_hwsize() returning 0.
> I think this is related to the fact that we currently don't use IRQ
> domains.

Correct and for some stupid reason I thought 0 is a good return value
here :)



diff --git a/kernel/irq/msi.c b/kernel/irq/msi.c
index bd4d4dd626b4..8fb10f216dc0 100644
--- a/kernel/irq/msi.c
+++ b/kernel/irq/msi.c
@@ -609,8 +609,8 @@ static unsigned int msi_domain_get_hwsize(struct device *dev, unsigned int domid
 		info = domain->host_data;
 		return info->hwsize;
 	}
-	/* No domain, no size... */
-	return 0;
+	/* No domain, default to MSI_MAX_INDEX */
+	return MSI_MAX_INDEX;
 }
 
 static inline void irq_chip_write_msi_msg(struct irq_data *data,