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 09/10] xen/arm: introduce phys/dma translations in xen_dma_sync_for_*
Date: Thu, 21 May 2020 13:08:56 -0700 (PDT) [thread overview]
Message-ID: <alpine.DEB.2.21.2005211247461.27502@sstabellini-ThinkPad-T480s> (raw)
In-Reply-To: <83c1120f-fe63-dc54-7b82-15a91c748de8@xen.org>
On Thu, 21 May 2020, Julien Grall wrote:
> > @@ -97,8 +98,7 @@ bool xen_arch_need_swiotlb(struct device *dev,
> > phys_addr_t phys,
> > dma_addr_t dev_addr)
> > {
> > - unsigned int xen_pfn = XEN_PFN_DOWN(phys);
> > - unsigned int bfn = XEN_PFN_DOWN(dev_addr);
> > + unsigned int bfn = XEN_PFN_DOWN(dma_to_phys(dev, dev_addr));
> > /*
> > * The swiotlb buffer should be used if
> > @@ -115,7 +115,7 @@ bool xen_arch_need_swiotlb(struct device *dev,
> > * require a bounce buffer because the device doesn't support coherent
> > * memory and we are not able to flush the cache.
> > */
> > - return (!hypercall_cflush && (xen_pfn != bfn) &&
> > + return (!hypercall_cflush && !pfn_valid(bfn) &&
>
> I believe this change is incorrect. The bfn is a frame based on Xen page
> granularity (always 4K) while pfn_valid() is expecting a frame based on the
> Kernel page granularity.
Given that kernel granularity >= xen granularity it looks like it would
be safe to use PFN_DOWN instead of XEN_PFN_DOWN:
unsigned int bfn = PFN_DOWN(dma_to_phys(dev, dev_addr));
return (!hypercall_cflush && !pfn_valid(bfn) &&
next prev parent reply other threads:[~2020-05-21 20:09 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
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 [this message]
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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