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Subject[PATCH v6 11/19] swiotlb-xen: use xen_alloc/free_coherent_pages
Date
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>
---
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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