On Mon, Jan 12, 2015 at 06:09:33PM +0000, Stefano Stabellini wrote: > Hi all, > I would like to request a backport of the following commit: > > > commit a4dba130891271084344c12537731542ec77cb85 > Author: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx> > Date: Fri Nov 21 11:07:39 2014 +0000 > > xen/arm/arm64: introduce xen_arch_need_swiotlb > > > to stable trees from 3.16 onward (3.16 included). > > > The commit needs to be slightly modified because is_device_dma_coherent > is not available on kernels < 3.19, so I just removed the call, > thus assuming that the device is not coherent on arm (slower but safe): > > diff --git a/arch/arm/xen/mm.c b/arch/arm/xen/mm.c > -index ab700e1..28ebf3e 100644 > +index b0e77de..f8a576b 100644 > --- a/arch/arm/xen/mm.c > +++ b/arch/arm/xen/mm.c > -@@ -100,6 +100,13 @@ void __xen_dma_sync_single_for_device(struct device *hwdev, > - __xen_dma_page_cpu_to_dev(hwdev, handle, size, dir); > - } > +@@ -16,6 +16,13 @@ > + #include <asm/xen/hypercall.h> > + #include <asm/xen/interface.h> > > +bool xen_arch_need_swiotlb(struct device *dev, > + unsigned long pfn, > + unsigned long mfn) > +{ > -+ return ((pfn != mfn) && !is_device_dma_coherent(dev)); > ++ return (pfn != mfn); > +} > + > int xen_create_contiguous_region(phys_addr_t pstart, unsigned int order, > > > The modified patch follows. > > Thank you Stefano, I will queue this for the next 3.16 kernel. Cheers, -- Luís > --- > > xen/arm/arm64: introduce xen_arch_need_swiotlb > > From: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx> > > Introduce an arch specific function to find out whether a particular dma > mapping operation needs to bounce on the swiotlb buffer. > > On ARM and ARM64, if the page involved is a foreign page and the device > is not coherent, we need to bounce because at unmap time we cannot > execute any required cache maintenance operations (we don't know how to > find the pfn from the mfn). > > No change of behaviour for x86. > > Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx> > Reviewed-by: David Vrabel <david.vrabel@xxxxxxxxxx> > Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx> > Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx> > Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> > > diff --git a/arch/arm/include/asm/xen/page.h b/arch/arm/include/asm/xen/page.h > index 135c24a..68c739b 100644 > --- a/arch/arm/include/asm/xen/page.h > +++ b/arch/arm/include/asm/xen/page.h > @@ -107,4 +107,8 @@ static inline bool set_phys_to_machine(unsigned long pfn, unsigned long mfn) > #define xen_remap(cookie, size) ioremap_cache((cookie), (size)) > #define xen_unmap(cookie) iounmap((cookie)) > > +bool xen_arch_need_swiotlb(struct device *dev, > + unsigned long pfn, > + unsigned long mfn); > + > #endif /* _ASM_ARM_XEN_PAGE_H */ > diff --git a/arch/arm/xen/mm.c b/arch/arm/xen/mm.c > index b0e77de..f8a576b 100644 > --- a/arch/arm/xen/mm.c > +++ b/arch/arm/xen/mm.c > @@ -16,6 +16,13 @@ > #include <asm/xen/hypercall.h> > #include <asm/xen/interface.h> > > +bool xen_arch_need_swiotlb(struct device *dev, > + unsigned long pfn, > + unsigned long mfn) > +{ > + return (pfn != mfn); > +} > + > int xen_create_contiguous_region(phys_addr_t pstart, unsigned int order, > unsigned int address_bits, > dma_addr_t *dma_handle) > diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h > index c949923..f58ef6c 100644 > --- a/arch/x86/include/asm/xen/page.h > +++ b/arch/x86/include/asm/xen/page.h > @@ -236,4 +236,11 @@ void make_lowmem_page_readwrite(void *vaddr); > #define xen_remap(cookie, size) ioremap((cookie), (size)); > #define xen_unmap(cookie) iounmap((cookie)) > > +static inline bool xen_arch_need_swiotlb(struct device *dev, > + unsigned long pfn, > + unsigned long mfn) > +{ > + return false; > +} > + > #endif /* _ASM_X86_XEN_PAGE_H */ > diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c > index ebd8f21..ac5d41b 100644 > --- a/drivers/xen/swiotlb-xen.c > +++ b/drivers/xen/swiotlb-xen.c > @@ -399,7 +399,9 @@ dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page, > * buffering it. > */ > if (dma_capable(dev, dev_addr, size) && > - !range_straddles_page_boundary(phys, size) && !swiotlb_force) { > + !range_straddles_page_boundary(phys, size) && > + !xen_arch_need_swiotlb(dev, PFN_DOWN(phys), PFN_DOWN(dev_addr)) && > + !swiotlb_force) { > /* we are not interested in the dma_addr returned by > * xen_dma_map_page, only in the potential cache flushes executed > * by the function. */ > @@ -557,6 +559,7 @@ xen_swiotlb_map_sg_attrs(struct device *hwdev, struct scatterlist *sgl, > dma_addr_t dev_addr = xen_phys_to_bus(paddr); > > if (swiotlb_force || > + xen_arch_need_swiotlb(hwdev, PFN_DOWN(paddr), PFN_DOWN(dev_addr)) || > !dma_capable(hwdev, dev_addr, sg->length) || > range_straddles_page_boundary(paddr, sg->length)) { > phys_addr_t map = swiotlb_tbl_map_single(hwdev, > -- > To unsubscribe from this list: send the line "unsubscribe stable" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html