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[Xen-devel] [PATCH v6 11/19] swiotlb-xen: use xen_alloc/free_coherent_pages



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@xxxxxxxxxxxxx>
---
 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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