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@eu.citrix.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

4 files changed, 31 insertions, 17 deletions

diff --git a/arch/arm/xen/mm.c b/arch/arm/xen/mm.c
index 0d69b874d249..b0e77de99148 100644
--- a/arch/arm/xen/mm.c
+++ b/arch/arm/xen/mm.c
@@ -16,7 +16,7 @@
 #include <asm/xen/hypercall.h>
 #include <asm/xen/interface.h>
 
-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)
 {
@@ -24,12 +24,12 @@ int xen_create_contiguous_region(unsigned long vstart, unsigned int order,
                 return -EINVAL;
 
         /* we assume that dom0 is mapped 1:1 for now */
-        *dma_handle = virt_to_phys(pstart);
+        *dma_handle = pstart;
         return 0;
 }
 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)
 {
         return;
 }
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 6c34d7c03d5b..883088368ff0 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 d8ef0bf577d2..189b8db5c983 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -43,6 +43,7 @@
 #include <xen/xen-ops.h>
 #include <xen/hvc-console.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
  * swiotlb_tbl_sync_single_*, to see if the memory was in fact allocated by this
@@ -142,6 +143,7 @@ xen_swiotlb_fixup(void *buf, size_t size, unsigned long nslabs)
         int i, rc;
         int dma_bits;
         dma_addr_t dma_handle;
+        phys_addr_t p = virt_to_phys(buf);
 
         dma_bits = get_order(IO_TLB_SEGSIZE << IO_TLB_SHIFT) + PAGE_SHIFT;
 
@@ -151,7 +153,7 @@ 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, &dma_handle);
                 } while (rc && dma_bits++ < max_dma_bits);
@@ -279,7 +281,6 @@ 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;
 
@@ -294,8 +295,12 @@ 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;
@@ -303,15 +308,19 @@ 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 (((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;
                 }
         }
@@ -334,13 +343,15 @@ 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 (((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);
 
-        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 9ef704d3a9dd..fb2ea8f26552 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,