From: keith.busch@intel.com (Keith Busch)
Subject: [PATCH for-4.13] nvme-pci: use dma memory for the host memory buffer descriptors
Date: Tue, 29 Aug 2017 18:00:12 -0400 [thread overview]
Message-ID: <20170829220012.GE4428@localhost.localdomain> (raw)
In-Reply-To: <20170828084718.29007-1-hch@lst.de>
On Mon, Aug 28, 2017@10:47:18AM +0200, Christoph Hellwig wrote:
> The NVMe 1.3 specification says in section 5.21.1.13:
>
> "After a successful completion of a Set Features enabling the host memory
> buffer, the host shall not write to the associated host memory region,
> buffer size, or descriptor list until the host memory buffer has been
> disabled."
>
> While this doesn't state that the descriptor list must remain accessible
> to the device it certainly implies it must remaing readable by the device.
>
> So switch to a dma coherent allocation for the descriptor list just to be
> safe - it's not like the cost for it matters compared to the actual
> memory buffers.
>
> Signed-off-by: Christoph Hellwig <hch at lst.de>
Looks good to me.
Reviewed-by: Keith Busch <keith.busch at intel.com>
next prev parent reply other threads:[~2017-08-29 22:00 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-28 8:47 [PATCH for-4.13] nvme-pci: use dma memory for the host memory buffer descriptors Christoph Hellwig
2017-08-29 13:13 ` Christoph Hellwig
2017-08-29 13:59 ` Johannes Thumshirn
2017-08-29 14:50 ` Christoph Hellwig
2017-08-29 22:00 ` Keith Busch [this message]
2017-08-30 10:05 ` Sagi Grimberg
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