linux-kernel - Re: [PATCH v1 04/17] dma-mapping: Add check if IOVA can be used

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Message-ID: <20241110151938.GA71181@unreal>
Date: Sun, 10 Nov 2024 17:19:38 +0200
From: Leon Romanovsky <leon@...nel.org>
To: Zhu Yanjun <yanjun.zhu@...ux.dev>
Cc: Jens Axboe <axboe@...nel.dk>, Jason Gunthorpe <jgg@...pe.ca>,
	Robin Murphy <robin.murphy@....com>, Joerg Roedel <joro@...tes.org>,
	Will Deacon <will@...nel.org>, Christoph Hellwig <hch@....de>,
	Sagi Grimberg <sagi@...mberg.me>, Keith Busch <kbusch@...nel.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Logan Gunthorpe <logang@...tatee.com>,
	Yishai Hadas <yishaih@...dia.com>,
	Shameer Kolothum <shameerali.kolothum.thodi@...wei.com>,
	Kevin Tian <kevin.tian@...el.com>,
	Alex Williamson <alex.williamson@...hat.com>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Jérôme Glisse <jglisse@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jonathan Corbet <corbet@....net>, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
	linux-rdma@...r.kernel.org, iommu@...ts.linux.dev,
	linux-nvme@...ts.infradead.org, linux-pci@...r.kernel.org,
	kvm@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH v1 04/17] dma-mapping: Add check if IOVA can be used

On Sun, Nov 10, 2024 at 04:09:11PM +0100, Zhu Yanjun wrote:
> 在 2024/10/30 16:12, Leon Romanovsky 写道:
> > From: Leon Romanovsky <leonro@...dia.com>
> > 
> > This patch adds a check if IOVA can be used for the specific
> > transaction.
> > 
> > In the new API a DMA mapping transaction is identified by a
> > struct dma_iova_state, which holds some recomputed information
> > for the transaction which does not change for each page being
> > mapped.
> > 
> > Signed-off-by: Leon Romanovsky <leonro@...dia.com>
> > ---
> >   include/linux/dma-mapping.h | 33 +++++++++++++++++++++++++++++++++
> >   1 file changed, 33 insertions(+)
> > 
> > diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
> > index 1524da363734..6075e0708deb 100644
> > --- a/include/linux/dma-mapping.h
> > +++ b/include/linux/dma-mapping.h
> > @@ -76,6 +76,20 @@
> >   #define DMA_BIT_MASK(n)	(((n) == 64) ? ~0ULL : ((1ULL<<(n))-1))
> > +struct dma_iova_state {
> > +	size_t __size;
> > +};
> > +
> > +/*
> > + * Use the high bit to mark if we used swiotlb for one or more ranges.
> > + */
> > +#define DMA_IOVA_USE_SWIOTLB		(1ULL << 63)
> 
> A trivial problem.
> In the above macro, using BIT_ULL(63) is better?

You already asked same question and the answer is also the same.
https://lore.kernel.org/all/20241103151946.GA99170@unreal/

> 
> Zhu Yanjun