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>

2 files changed, 8 insertions, 5 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);