xen-devel.lists.xenproject.org archive mirror
 help / color / mirror / Atom feed
From: Julien Grall <julien@xen.org>
To: Stefano Stabellini <sstabellini@kernel.org>,
	jgross@suse.com, boris.ostrovsky@oracle.com,
	konrad.wilk@oracle.com
Cc: xen-devel@lists.xenproject.org,
	Stefano Stabellini <stefano.stabellini@xilinx.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 08/10] swiotlb-xen: introduce phys_to_dma/dma_to_phys translations
Date: Thu, 21 May 2020 09:07:53 +0100	[thread overview]
Message-ID: <0fa24e23-ee7a-3ff0-cee0-8734bcda5f6a@xen.org> (raw)
In-Reply-To: <20200520234520.22563-8-sstabellini@kernel.org>

Hi,

On 21/05/2020 00:45, Stefano Stabellini wrote:
> From: Stefano Stabellini <stefano.stabellini@xilinx.com>
> 
> Call dma_to_phys in is_xen_swiotlb_buffer.
> Call phys_to_dma in xen_phys_to_bus.
> Call dma_to_phys in xen_bus_to_phys.
> 
> Everything is taken care of by these changes except for
> xen_swiotlb_alloc_coherent and xen_swiotlb_free_coherent, which need a
> few explicit phys_to_dma/dma_to_phys calls.

The commit message explains what the code is doing but doesn't explain 
why this is needed.

> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
> ---
>   drivers/xen/swiotlb-xen.c | 20 ++++++++++++--------
>   1 file changed, 12 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
> index c50448fd9b75..d011c4c7aa72 100644
> --- a/drivers/xen/swiotlb-xen.c
> +++ b/drivers/xen/swiotlb-xen.c
> @@ -64,14 +64,16 @@ static inline dma_addr_t xen_phys_to_bus(struct device *dev, phys_addr_t paddr)
>   
>   	dma |= paddr & ~XEN_PAGE_MASK;
>   
> -	return dma;
> +	return phys_to_dma(dev, dma);
>   }
>   
> -static inline phys_addr_t xen_bus_to_phys(struct device *dev, dma_addr_t baddr)
> +static inline phys_addr_t xen_bus_to_phys(struct device *dev,
> +					  dma_addr_t dma_addr)
>   {
> +	phys_addr_t baddr = dma_to_phys(dev, dma_addr);
>   	unsigned long xen_pfn = bfn_to_pfn(XEN_PFN_DOWN(baddr));
> -	dma_addr_t dma = (dma_addr_t)xen_pfn << XEN_PAGE_SHIFT;
> -	phys_addr_t paddr = dma;
> +	phys_addr_t paddr = (xen_pfn << XEN_PAGE_SHIFT) |
> +			    (baddr & ~XEN_PAGE_MASK);
>   
>   	paddr |= baddr & ~XEN_PAGE_MASK;
>   
> @@ -99,7 +101,7 @@ static inline int range_straddles_page_boundary(phys_addr_t p, size_t size)
>   
>   static int is_xen_swiotlb_buffer(struct device *dev, dma_addr_t dma_addr)
>   {
> -	unsigned long bfn = XEN_PFN_DOWN(dma_addr);
> +	unsigned long bfn = XEN_PFN_DOWN(dma_to_phys(dev, dma_addr));
>   	unsigned long xen_pfn = bfn_to_local_pfn(bfn);
>   	phys_addr_t paddr = XEN_PFN_PHYS(xen_pfn);
>   
> @@ -304,11 +306,11 @@ xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
>   	if (hwdev && hwdev->coherent_dma_mask)
>   		dma_mask = hwdev->coherent_dma_mask;
>   
> -	/* At this point dma_handle is the physical address, next we are
> +	/* At this point dma_handle is the dma address, next we are
>   	 * going to set it to the machine address.
>   	 * Do not use virt_to_phys(ret) because on ARM it doesn't correspond
>   	 * to *dma_handle. */
> -	phys = *dma_handle;
> +	phys = dma_to_phys(hwdev, *dma_handle);
>   	dev_addr = xen_phys_to_bus(hwdev, phys);
>   	if (((dev_addr + size - 1 <= dma_mask)) &&
>   	    !range_straddles_page_boundary(phys, size))
> @@ -319,6 +321,7 @@ xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
>   			xen_free_coherent_pages(hwdev, size, ret, (dma_addr_t)phys, attrs);
>   			return NULL;
>   		}
> +		*dma_handle = phys_to_dma(hwdev, *dma_handle);
>   		SetPageXenRemapped(virt_to_page(ret));
>   	}
>   	memset(ret, 0, size);
> @@ -351,7 +354,8 @@ xen_swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr,
>   	    TestClearPageXenRemapped(pg))
>   		xen_destroy_contiguous_region(phys, order);
>   
> -	xen_free_coherent_pages(hwdev, size, vaddr, (dma_addr_t)phys, attrs);
> +	xen_free_coherent_pages(hwdev, size, vaddr, phys_to_dma(hwdev, phys),
> +				attrs);
>   }
>   
>   /*
> 

Cheers,

-- 
Julien Grall


  reply	other threads:[~2020-05-21  8:08 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-20 23:45 [PATCH 00/10] fix swiotlb-xen for RPi4 Stefano Stabellini
2020-05-20 23:45 ` [PATCH 01/10] swiotlb-xen: use vmalloc_to_page on vmalloc virt addresses Stefano Stabellini
2020-05-21  8:01   ` Julien Grall
2020-05-22  3:54     ` Stefano Stabellini
2020-05-22 18:11       ` Julien Grall
2020-05-22 20:36         ` Stefano Stabellini
2020-05-20 23:45 ` [PATCH 02/10] swiotlb-xen: remove start_dma_addr Stefano Stabellini
2020-05-21  8:05   ` Julien Grall
2020-05-22  3:55     ` Stefano Stabellini
2020-05-22 18:16       ` Julien Grall
2020-05-22 20:47         ` Stefano Stabellini
2020-05-20 23:45 ` [PATCH 03/10] swiotlb-xen: add struct device* parameter to xen_phys_to_bus Stefano Stabellini
2020-05-20 23:45 ` [PATCH 04/10] swiotlb-xen: add struct device* parameter to xen_bus_to_phys Stefano Stabellini
2020-05-20 23:45 ` [PATCH 05/10] swiotlb-xen: add struct device* parameter to xen_dma_sync_for_cpu Stefano Stabellini
2020-05-20 23:45 ` [PATCH 06/10] swiotlb-xen: add struct device* parameter to xen_dma_sync_for_device Stefano Stabellini
2020-05-20 23:45 ` [PATCH 07/10] swiotlb-xen: add struct device* parameter to is_xen_swiotlb_buffer Stefano Stabellini
2020-05-20 23:45 ` [PATCH 08/10] swiotlb-xen: introduce phys_to_dma/dma_to_phys translations Stefano Stabellini
2020-05-21  8:07   ` Julien Grall [this message]
2020-05-21 22:59   ` Boris Ostrovsky
2020-05-22 17:34     ` Stefano Stabellini
2020-05-22 18:29       ` Boris Ostrovsky
2020-05-20 23:45 ` [PATCH 09/10] xen/arm: introduce phys/dma translations in xen_dma_sync_for_* Stefano Stabellini
2020-05-21  8:18   ` Julien Grall
2020-05-21 20:08     ` Stefano Stabellini
2020-05-21 20:17       ` Julien Grall
2020-05-20 23:45 ` [PATCH 10/10] xen/arm: call dma_to_phys on the dma_addr_t parameter of dma_cache_maint Stefano Stabellini
2020-05-21  8:25   ` Julien Grall
2020-05-20 23:51 ` [PATCH 00/10] fix swiotlb-xen for RPi4 Roman Shaposhnik
2020-05-20 23:56   ` Stefano Stabellini
2020-06-02 21:51 ` Stefano Stabellini
2020-06-03  0:15   ` Boris Ostrovsky

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=0fa24e23-ee7a-3ff0-cee0-8734bcda5f6a@xen.org \
    --to=julien@xen.org \
    --cc=boris.ostrovsky@oracle.com \
    --cc=jgross@suse.com \
    --cc=konrad.wilk@oracle.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=sstabellini@kernel.org \
    --cc=stefano.stabellini@xilinx.com \
    --cc=xen-devel@lists.xenproject.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).