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From: Jason Gunthorpe <jgg@nvidia.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Leon Romanovsky <leon@kernel.org>,
	Doug Ledford <dledford@redhat.com>,
	Yishai Hadas <yishaih@nvidia.com>, <linux-rdma@vger.kernel.org>
Subject: Re: [PATCH rdma-next v2 1/4] IB/core: Improve ODP to use hmm_range_fault()
Date: Tue, 29 Sep 2020 15:13:25 -0300	[thread overview]
Message-ID: <20200929181325.GA9475@nvidia.com> (raw)
In-Reply-To: <20200929180210.GA5012@infradead.org>

On Tue, Sep 29, 2020 at 07:02:10PM +0100, Christoph Hellwig wrote:
> On Tue, Sep 29, 2020 at 02:59:46PM -0300, Jason Gunthorpe wrote:
> > This leaves *dma_addr set to ib_dma_mapping_error, which means the
> > next try to map it will fail the if (!dma_addr) and produce a
> > corrupted dma address.
> > 
> > *dma_addr should be set to 0 here
> 
> Maybe the code should use DMA_MAPPING_ERROR as the sentinel for a
> not mapped entry?

My eventual hope is to be able to send this DMA page list to the HW
without having to parse and copy it like is done today. We already
have it in a linear array that can be DMA'd from.

However, the HW knows 0 means need-fault (the flag bits are zero), it
doesn't know what to do with DMA_MAPPING_ERROR..

Jason

  reply	other threads:[~2020-09-29 18:13 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-22  8:21 [PATCH rdma-next v2 0/4] Improve ODP by using HMM API Leon Romanovsky
2020-09-22  8:21 ` [PATCH rdma-next v2 1/4] IB/core: Improve ODP to use hmm_range_fault() Leon Romanovsky
2020-09-29 17:59   ` Jason Gunthorpe
2020-09-29 18:02     ` Christoph Hellwig
2020-09-29 18:13       ` Jason Gunthorpe [this message]
2020-09-29 18:15         ` Christoph Hellwig
2020-09-29 18:27           ` Jason Gunthorpe
2020-09-29 20:20     ` Yishai Hadas
2020-09-29 19:27   ` Jason Gunthorpe
2020-09-29 20:09     ` Yishai Hadas
2020-09-29 20:13       ` Jason Gunthorpe
2020-09-29 20:30         ` Yishai Hadas
2020-09-30  0:37           ` Jason Gunthorpe
2020-09-29 21:34         ` Yishai Hadas
2020-09-30  0:35           ` Jason Gunthorpe
2020-09-30  7:32             ` Yishai Hadas
2020-09-22  8:21 ` [PATCH rdma-next v2 2/4] IB/core: Enable ODP sync without faulting Leon Romanovsky
2020-09-22  8:21 ` [PATCH rdma-next v2 3/4] RDMA/mlx5: Extend advice MR to support non faulting mode Leon Romanovsky
2020-09-22  8:21 ` [PATCH rdma-next v2 4/4] RDMA/mlx5: Sync device with CPU pages upon ODP MR registration Leon Romanovsky

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