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From: Christoph Hellwig <hch@infradead.org>
To: Jean-Philippe Brucker <jean-philippe@linaro.org>
Cc: dwmw2@infradead.org, baolu.lu@linux.intel.com, joro@8bytes.org,
	zhangfei.gao@linaro.org, wangzhou1@hisilicon.com, arnd@arndb.de,
	gregkh@linuxfoundation.org, iommu@lists.linux-foundation.org,
	linux-kernel@vger.kernel.org,
	linux-accelerators@lists.ozlabs.org, kevin.tian@intel.com,
	jacob.jun.pan@linux.intel.com, ashok.raj@intel.com,
	linux-pci@vger.kernel.org
Subject: Re: [RFC PATCH 2/2] iommu: Add IOMMU_UNBIND_FAULT_PENDING flag
Date: Fri, 16 Oct 2020 08:07:59 +0100
Message-ID: <20201016070759.GA12905@infradead.org> (raw)
In-Reply-To: <20201015090028.1278108-3-jean-philippe@linaro.org>

On Thu, Oct 15, 2020 at 11:00:29AM +0200, Jean-Philippe Brucker wrote:
> IOMMU drivers only need to flush their PRI queue when faults might be
> pending. According to the PCIe spec (quoted below) this only happens
> when using the "Stop Marker" method. Otherwise the function waits for
> pending faults before signaling to the device driver that it can
> unbind().
> 
> Add the IOMMU_UNBIND_FAULT_PENDING flags to unbind(), to tell the IOMMU
> driver whether it's worth flushing the queue.

As we have no code using the "stop marker" method please just remove
the code entirely instead of adding a flag that is just dead code.

  reply index

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-15  9:00 [RFC PATCH 0/2] iommu: Avoid unnecessary PRI queue flushes Jean-Philippe Brucker
2020-10-15  9:00 ` [RFC PATCH 1/2] iommu: Add flags to sva_unbind() Jean-Philippe Brucker
2020-10-15  9:00 ` [RFC PATCH 2/2] iommu: Add IOMMU_UNBIND_FAULT_PENDING flag Jean-Philippe Brucker
2020-10-16  7:07   ` Christoph Hellwig [this message]
2020-10-15 18:22 ` [RFC PATCH 0/2] iommu: Avoid unnecessary PRI queue flushes Raj, Ashok
2020-10-16  7:59   ` Jean-Philippe Brucker
2020-10-17 11:25     ` Raj, Ashok
2020-10-19 14:08       ` Jean-Philippe Brucker
2020-10-19 18:33         ` Jacob Pan
2020-10-23 13:30           ` Jean-Philippe Brucker
2020-10-19 21:16         ` Raj, Ashok
2020-10-23 13:34           ` Jean-Philippe Brucker

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