linux-kernel - MSI number limit for PCI hotplug under PCI bridge on ARM platform

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Message-ID: <327ba551-2cbd-08bb-d4c1-107c3ff7d45d@huawei.com>
Date:   Mon, 1 Apr 2019 21:55:52 +0800
From:   Heyi Guo <guoheyi@...wei.com>
To:     <linux-kernel@...r.kernel.org>
CC:     Marc Zyngier <marc.zyngier@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        wanghaibin 00208455 <wanghaibin.wang@...wei.com>
Subject: MSI number limit for PCI hotplug under PCI bridge on ARM platform

Hi folks,

In current kernel implementation for ARM platform, all devices under one PCI bridge share a same device ID and the total number of MSI interrupts is fixed at the first time any child device is allocating MSI. However, this may cause failure of allocating MSI if the system supports device hot-plug under the PCI bridge, which is possible for ARM virtual machine with generic pcie-to-pci-bridge and kernel config HOTPLUG_PCI_SHPC enabled.

Does it make sense to add support for the above scenario? If it does, any suggestion for how to do that?

Thanks,

Heyi