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    SubjectRe: [PATCH v6 11/19] swiotlb-xen: use xen_alloc/free_coherent_pages
    On Fri, Sep 27, 2013 at 05:09:59PM +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 only works for kernel
    > direct mapped RAM memory.
    > In ARM case the pointer could be an ioremap address, therefore passing
    > it to virt_to_phys would give you another physical address that doesn't
    > correspond to it.
    >
    > Make xen_create_contiguous_region take a phys_addr_t as start parameter to
    > avoid the virt_to_phys calls which would be incorrect.
    >
    > Changes in v6:
    > - remove extra spaces.
    >
    > Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

    Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
    > ---
    > arch/arm/xen/mm.c | 7 +++----
    > arch/x86/xen/mmu.c | 7 +++++--
    > drivers/xen/swiotlb-xen.c | 31 +++++++++++++++++++++----------
    > include/xen/xen-ops.h | 4 ++--
    > 4 files changed, 31 insertions(+), 18 deletions(-)
    >
    > diff --git a/arch/arm/xen/mm.c b/arch/arm/xen/mm.c
    > index 4330b15..b305b94 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..8830883 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);
    >
    > /*
    > * 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);
    > 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 deb9131..96ad316 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;
    > struct xen_dma_info *dma_info = NULL;
    > @@ -405,8 +406,12 @@ 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;
    > + /* On ARM this function returns an ioremap'ped virtual address for
    > + * which virt_to_phys doesn't return the corresponding physical
    > + * address. In fact on ARM virt_to_phys only works for kernel direct
    > + * mapped RAM memory. Also see comment below.
    > + */
    > + ret = xen_alloc_coherent_pages(hwdev, size, dma_handle, flags, attrs);
    >
    > if (!ret)
    > return ret;
    > @@ -414,16 +419,20 @@ 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;
    > }
    >
    > @@ -463,18 +472,20 @@ 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);
    > + xen_destroy_contiguous_region(phys, order);
    > dma_info = xen_get_dma_info_from_dma(dev_addr);
    > rb_erase(&dma_info->rbnode, &bus_to_phys);
    > kfree(dma_info);
    > }
    >
    > - 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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