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Message-ID: <96051115-c928-4f3c-bd65-4f3f8e83ca9c@linux.intel.com>
Date:   Wed, 13 Dec 2023 19:59:42 +0800
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Cc:     baolu.lu@linux.intel.com, linux-pci@vger.kernel.org,
        iommu@lists.linux.dev, linux-kernel@vger.kernel.org,
        Haorong Ye <yehaorong@bytedance.com>
Subject: Re: [PATCH 2/2] iommu/vt-d: don's issue devTLB flush request when
 device is disconnected
To:     Ethan Zhao <haifeng.zhao@linux.intel.com>, bhelgaas@google.com,
        dwmw2@infradead.org, will@kernel.org, robin.murphy@arm.com
References: <20231213034637.2603013-1-haifeng.zhao@linux.intel.com>
 <20231213034637.2603013-3-haifeng.zhao@linux.intel.com>
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From:   Baolu Lu <baolu.lu@linux.intel.com>
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On 2023/12/13 11:46, Ethan Zhao wrote:
> For those endpoint devices connect to system via hotplug capable ports,
> users could request a warm reset to the device by flapping device's link
> through setting the slot's link control register, as pciehpt_ist() DLLSC
> interrupt sequence response, pciehp will unload the device driver and
> then power it off.

Is it possible for pciehp to disable ATS on the device before unloading
the driver? Or should the device follow some specific steps to warm
reset the device?

What happens if IOMMU issues device TLB invalidation after link down but
before pci_dev_is_disconnected() returns true?

Best regards,
baolu