From: Stefano Stabellini <sstabellini@kernel.org>
To: Julien Grall <julien@xen.org>
Cc: jgross@suse.com, Stefano Stabellini <sstabellini@kernel.org>,
konrad.wilk@oracle.com, linux-kernel@vger.kernel.org,
xen-devel@lists.xenproject.org, boris.ostrovsky@oracle.com,
Stefano Stabellini <stefano.stabellini@xilinx.com>
Subject: Re: [PATCH 02/10] swiotlb-xen: remove start_dma_addr
Date: Thu, 21 May 2020 20:55:18 -0700 (PDT) [thread overview]
Message-ID: <alpine.DEB.2.21.2005211243060.27502@sstabellini-ThinkPad-T480s> (raw)
In-Reply-To: <6241b8f6-5c51-0486-55ae-d571b117a184@xen.org>
On Thu, 21 May 2020, Julien Grall wrote:
> Hi,
>
> On 21/05/2020 00:45, Stefano Stabellini wrote:
> > From: Stefano Stabellini <stefano.stabellini@xilinx.com>
> >
> > It is not strictly needed. Call virt_to_phys on xen_io_tlb_start
> > instead. It will be useful not to have a start_dma_addr around with the
> > next patches.
> >
> > Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
> > ---
> > drivers/xen/swiotlb-xen.c | 5 +----
> > 1 file changed, 1 insertion(+), 4 deletions(-)
> >
> > diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
> > index a42129cba36e..b5e0492b07b9 100644
> > --- a/drivers/xen/swiotlb-xen.c
> > +++ b/drivers/xen/swiotlb-xen.c
> > @@ -52,8 +52,6 @@ static unsigned long xen_io_tlb_nslabs;
> > * Quick lookup value of the bus address of the IOTLB.
> > */
> > -static u64 start_dma_addr;
> > -
> > /*
> > * Both of these functions should avoid XEN_PFN_PHYS because phys_addr_t
> > * can be 32bit when dma_addr_t is 64bit leading to a loss in
> > @@ -241,7 +239,6 @@ int __ref xen_swiotlb_init(int verbose, bool early)
> > m_ret = XEN_SWIOTLB_EFIXUP;
> > goto error;
> > }
> > - start_dma_addr = xen_virt_to_bus(xen_io_tlb_start);
> > if (early) {
> > if (swiotlb_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs,
> > verbose))
> > @@ -389,7 +386,7 @@ static dma_addr_t xen_swiotlb_map_page(struct device
> > *dev, struct page *page,
> > */
> > trace_swiotlb_bounced(dev, dev_addr, size, swiotlb_force);
> > - map = swiotlb_tbl_map_single(dev, start_dma_addr, phys,
> > + map = swiotlb_tbl_map_single(dev, virt_to_phys(xen_io_tlb_start),
> > phys,
>
> xen_virt_to_bus() is implemented as xen_phys_to_bus(virt_to_phys()). Can you
> explain how the two are equivalent?
They are not equivalent. Looking at what swiotlb_tbl_map_single expects,
and also the implementation of swiotlb_init_with_tbl, I think
virt_to_phys is actually the one we want.
swiotlb_tbl_map_single compares the argument with __pa(tlb) which is
__pa(xen_io_tlb_start) which is virt_to_phys(xen_io_tlb_start).
next prev parent reply other threads:[~2020-05-22 3:55 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 [this message]
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
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
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