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Message-ID: <20130830135333.GL21239@phenom.dumpdata.com>
Date: Fri, 30 Aug 2013 09:53:33 -0400
From: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To: Stefano Stabellini <stefano.stabellini@...citrix.com>
Cc: xen-devel@...ts.xensource.com, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, Ian.Campbell@...rix.com
Subject: Re: [PATCH v5 12/13] swiotlb-xen: use xen_alloc/free_coherent_pages
On Thu, Aug 29, 2013 at 07:32:33PM +0100, Stefano Stabellini wrote:
> Use xen_alloc_coherent_pages and xen_free_coherent_pages to allocate or
> free coherent pages.
>
> We need to be careful handling the pointer returned by
> xen_alloc_coherent_pages, because on ARM the pointer is not equal to
> phys_to_virt(*dma_handle). In fact virt_to_phys on the returned pointer
> doesn't return a valid physical address.
Why is it called 'virt_to_phys'? What does it return then?
>
> Make xen_create_contiguous_region take a phys_addr_t as start parameter to
> avoid the virt_to_phys calls which would be incorrect.
>
> Signed-off-by: Stefano Stabellini <stefano.stabellini@...citrix.com>
> ---
> arch/arm/xen/mm.c | 7 +++----
> arch/x86/xen/mmu.c | 7 +++++--
> drivers/xen/swiotlb-xen.c | 24 +++++++++++++++---------
> include/xen/xen-ops.h | 4 ++--
> 4 files changed, 25 insertions(+), 17 deletions(-)
>
> diff --git a/arch/arm/xen/mm.c b/arch/arm/xen/mm.c
> index 1477ace..9163d4c 100644
> --- a/arch/arm/xen/mm.c
> +++ b/arch/arm/xen/mm.c
> @@ -55,11 +55,10 @@ static int xen_exchange_memory(xen_ulong_t extents_in,
> return success;
> }
>
> -int xen_create_contiguous_region(unsigned long vstart, unsigned int order,
> +int xen_create_contiguous_region(phys_addr_t pstart, unsigned int order,
> unsigned int address_bits,
> dma_addr_t *dma_handle)
> {
> - phys_addr_t pstart = __pa(vstart);
> xen_pfn_t in_frame, out_frame;
> int success;
>
> @@ -78,9 +77,9 @@ int xen_create_contiguous_region(unsigned long vstart, unsigned int order,
> }
> EXPORT_SYMBOL_GPL(xen_create_contiguous_region);
>
> -void xen_destroy_contiguous_region(unsigned long vstart, unsigned int order)
> +void xen_destroy_contiguous_region(phys_addr_t pstart, unsigned int order)
> {
> - xen_pfn_t in_frame = __pa(vstart) >> PAGE_SHIFT;
> + xen_pfn_t in_frame = pstart >> PAGE_SHIFT;
> struct xen_unpin unpin = {
> .in = {
> .nr_extents = 1,
> diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
> index 6c34d7c..07ee0e8 100644
> --- a/arch/x86/xen/mmu.c
> +++ b/arch/x86/xen/mmu.c
> @@ -2328,13 +2328,14 @@ static int xen_exchange_memory(unsigned long extents_in, unsigned int order_in,
> return success;
> }
>
> -int xen_create_contiguous_region(unsigned long vstart, unsigned int order,
> +int xen_create_contiguous_region(phys_addr_t pstart, unsigned int order,
> unsigned int address_bits,
> dma_addr_t *dma_handle)
> {
> unsigned long *in_frames = discontig_frames, out_frame;
> unsigned long flags;
> int success;
> + unsigned long vstart = (unsigned long) phys_to_virt(pstart);
Extra space.
>
> /*
> * Currently an auto-translated guest will not perform I/O, nor will
> @@ -2374,11 +2375,12 @@ int xen_create_contiguous_region(unsigned long vstart, unsigned int order,
> }
> EXPORT_SYMBOL_GPL(xen_create_contiguous_region);
>
> -void xen_destroy_contiguous_region(unsigned long vstart, unsigned int order)
> +void xen_destroy_contiguous_region(phys_addr_t pstart, unsigned int order)
> {
> unsigned long *out_frames = discontig_frames, in_frame;
> unsigned long flags;
> int success;
> + unsigned long vstart;
>
> if (xen_feature(XENFEAT_auto_translated_physmap))
> return;
> @@ -2386,6 +2388,7 @@ void xen_destroy_contiguous_region(unsigned long vstart, unsigned int order)
> if (unlikely(order > MAX_CONTIG_ORDER))
> return;
>
> + vstart = (unsigned long) phys_to_virt(pstart);
Ditto
> memset((void *) vstart, 0, PAGE_SIZE << order);
>
> spin_lock_irqsave(&xen_reservation_lock, flags);
> diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
> index 010da31..c96b928 100644
> --- a/drivers/xen/swiotlb-xen.c
> +++ b/drivers/xen/swiotlb-xen.c
> @@ -46,6 +46,7 @@
> #include <xen/hvc-console.h>
> #include <xen/features.h>
> #include <asm/dma-mapping.h>
> +#include <asm/xen/page-coherent.h>
>
> /*
> * Used to do a quick range check in swiotlb_tbl_unmap_single and
> @@ -244,6 +245,7 @@ xen_swiotlb_fixup(void *buf, size_t size, unsigned long nslabs)
> {
> int i, j, rc;
> int dma_bits;
> + phys_addr_t p = virt_to_phys(buf);
>
> dma_bits = get_order(IO_TLB_SEGSIZE << IO_TLB_SHIFT) + PAGE_SHIFT;
>
> @@ -253,7 +255,7 @@ xen_swiotlb_fixup(void *buf, size_t size, unsigned long nslabs)
>
> do {
> rc = xen_create_contiguous_region(
> - (unsigned long)buf + (i << IO_TLB_SHIFT),
> + p + (i << IO_TLB_SHIFT),
> get_order(slabs << IO_TLB_SHIFT),
> dma_bits, &xen_dma_seg[j].dma_addr);
> } while (rc && dma_bits++ < max_dma_bits);
> @@ -389,7 +391,6 @@ xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
> void *ret;
> int order = get_order(size);
> u64 dma_mask = DMA_BIT_MASK(32);
> - unsigned long vstart;
> phys_addr_t phys;
> dma_addr_t dev_addr;
>
> @@ -404,8 +405,7 @@ xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
> if (dma_alloc_from_coherent(hwdev, size, dma_handle, &ret))
> return ret;
>
> - vstart = __get_free_pages(flags, order);
> - ret = (void *)vstart;
> + ret = xen_alloc_coherent_pages(hwdev, size, dma_handle, flags, attrs);
>
> if (!ret)
> return ret;
> @@ -413,16 +413,20 @@ xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
> if (hwdev && hwdev->coherent_dma_mask)
> dma_mask = dma_alloc_coherent_mask(hwdev, flags);
>
> - phys = virt_to_phys(ret);
> + /* At this point dma_handle is the physical 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;
> dev_addr = xen_phys_to_bus(phys);
> if (!xen_feature(XENFEAT_auto_translated_physmap) &&
> ((dev_addr + size - 1 <= dma_mask)) &&
> !range_straddles_page_boundary(phys, size))
> *dma_handle = dev_addr;
> else {
> - if (xen_create_contiguous_region(vstart, order,
> + if (xen_create_contiguous_region(phys, order,
> fls64(dma_mask), dma_handle) != 0) {
> - free_pages(vstart, order);
> + xen_free_coherent_pages(hwdev, size, ret, (dma_addr_t)phys, attrs);
> return NULL;
> }
> }
> @@ -445,14 +449,16 @@ xen_swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr,
> if (hwdev && hwdev->coherent_dma_mask)
> dma_mask = hwdev->coherent_dma_mask;
>
> - phys = virt_to_phys(vaddr);
> + /* do not use virt_to_phys because on ARM it doesn't return you the
> + * physical address */
> + phys = xen_bus_to_phys(dev_addr);
>
> if (xen_feature(XENFEAT_auto_translated_physmap) ||
> (((dev_addr + size - 1 > dma_mask)) ||
> range_straddles_page_boundary(phys, size)))
> xen_destroy_contiguous_region((unsigned long)vaddr, order);
>
> - free_pages((unsigned long)vaddr, order);
> + xen_free_coherent_pages(hwdev, size, vaddr, (dma_addr_t)phys, attrs);
> }
> EXPORT_SYMBOL_GPL(xen_swiotlb_free_coherent);
>
> diff --git a/include/xen/xen-ops.h b/include/xen/xen-ops.h
> index 9ef704d..fb2ea8f 100644
> --- a/include/xen/xen-ops.h
> +++ b/include/xen/xen-ops.h
> @@ -19,11 +19,11 @@ void xen_arch_resume(void);
> int xen_setup_shutdown_event(void);
>
> extern unsigned long *xen_contiguous_bitmap;
> -int xen_create_contiguous_region(unsigned long vstart, unsigned int order,
> +int xen_create_contiguous_region(phys_addr_t pstart, unsigned int order,
> unsigned int address_bits,
> dma_addr_t *dma_handle);
>
> -void xen_destroy_contiguous_region(unsigned long vstart, unsigned int order);
> +void xen_destroy_contiguous_region(phys_addr_t pstart, unsigned int order);
>
> struct vm_area_struct;
> int xen_remap_domain_mfn_range(struct vm_area_struct *vma,
> --
> 1.7.2.5
>
--
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