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Subject[PATCH v6 06/19] xen/arm,arm64: enable SWIOTLB_XEN
Date
Xen on arm and arm64 needs SWIOTLB_XEN: when running on Xen we need to
program the hardware with mfns rather than pfns for dma addresses.
Remove SWIOTLB_XEN dependency on X86 and PCI and make XEN select
SWIOTLB_XEN on arm and arm64.

At the moment always rely on swiotlb-xen, but when Xen starts supporting
hardware IOMMUs we'll be able to avoid it conditionally on the presence
of an IOMMU on the platform.

Implement xen_create_contiguous_region on arm and arm64 by using
XENMEM_exchange_and_pin.

Initialize the xen-swiotlb from xen_early_init (before the native
dma_ops are initialized), set xen_dma_ops to &xen_swiotlb_dma_ops.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>


Changes in v6:
- introduce and export xen_dma_ops;
- call xen_mm_init from as arch_initcall.

Changes in v4:
- remove redefinition of DMA_ERROR_CODE;
- update the code to use XENMEM_exchange_and_pin and XENMEM_unpin;
- add a note about hardware IOMMU in the commit message.

Changes in v3:
- code style changes;
- warn on XENMEM_put_dma_buf failures.
---
arch/arm/Kconfig | 1 +
arch/arm/include/asm/xen/hypervisor.h | 2 +
arch/arm/include/asm/xen/page.h | 2 +
arch/arm/xen/Makefile | 2 +-
arch/arm/xen/mm.c | 121 +++++++++++++++++++++++++++++++++
arch/arm64/Kconfig | 1 +
arch/arm64/xen/Makefile | 2 +-
drivers/xen/Kconfig | 1 -
drivers/xen/swiotlb-xen.c | 16 +++++
9 files changed, 145 insertions(+), 3 deletions(-)
create mode 100644 arch/arm/xen/mm.c

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index c0bfb33..2c9d112 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1848,6 +1848,7 @@ config XEN
depends on CPU_V7 && !CPU_V6
depends on !GENERIC_ATOMIC64
select ARM_PSCI
+ select SWIOTLB_XEN
help
Say Y if you want to run Linux in a Virtual Machine on Xen on ARM.

diff --git a/arch/arm/include/asm/xen/hypervisor.h b/arch/arm/include/asm/xen/hypervisor.h
index d7ab99a..1317ee4 100644
--- a/arch/arm/include/asm/xen/hypervisor.h
+++ b/arch/arm/include/asm/xen/hypervisor.h
@@ -16,4 +16,6 @@ static inline enum paravirt_lazy_mode paravirt_get_lazy_mode(void)
return PARAVIRT_LAZY_NONE;
}

+extern struct dma_map_ops *xen_dma_ops;
+
#endif /* _ASM_ARM_XEN_HYPERVISOR_H */
diff --git a/arch/arm/include/asm/xen/page.h b/arch/arm/include/asm/xen/page.h
index 359a7b5..b0f7150 100644
--- a/arch/arm/include/asm/xen/page.h
+++ b/arch/arm/include/asm/xen/page.h
@@ -6,12 +6,14 @@

#include <linux/pfn.h>
#include <linux/types.h>
+#include <linux/dma-mapping.h>

#include <xen/interface/grant_table.h>

#define pfn_to_mfn(pfn) (pfn)
#define phys_to_machine_mapping_valid(pfn) (1)
#define mfn_to_pfn(mfn) (mfn)
+#define mfn_to_local_pfn(m) (mfn_to_pfn(m))
#define mfn_to_virt(m) (__va(mfn_to_pfn(m) << PAGE_SHIFT))

#define pte_mfn pte_pfn
diff --git a/arch/arm/xen/Makefile b/arch/arm/xen/Makefile
index 4384103..66fc35d 100644
--- a/arch/arm/xen/Makefile
+++ b/arch/arm/xen/Makefile
@@ -1 +1 @@
-obj-y := enlighten.o hypercall.o grant-table.o
+obj-y := enlighten.o hypercall.o grant-table.o mm.o
diff --git a/arch/arm/xen/mm.c b/arch/arm/xen/mm.c
new file mode 100644
index 0000000..b065c98
--- /dev/null
+++ b/arch/arm/xen/mm.c
@@ -0,0 +1,121 @@
+#include <linux/bootmem.h>
+#include <linux/gfp.h>
+#include <linux/export.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/dma-mapping.h>
+#include <linux/vmalloc.h>
+#include <linux/swiotlb.h>
+
+#include <xen/xen.h>
+#include <xen/interface/memory.h>
+#include <xen/swiotlb-xen.h>
+
+#include <asm/cacheflush.h>
+#include <asm/xen/page.h>
+#include <asm/xen/hypercall.h>
+#include <asm/xen/interface.h>
+
+static int xen_exchange_memory(xen_ulong_t extents_in,
+ unsigned int order_in,
+ xen_pfn_t *pfns_in,
+ xen_ulong_t extents_out,
+ unsigned int order_out,
+ xen_pfn_t *mfns_out,
+ unsigned int address_bits)
+{
+ long rc;
+ int success;
+
+ struct xen_memory_exchange exchange = {
+ .in = {
+ .nr_extents = extents_in,
+ .extent_order = order_in,
+ .domid = DOMID_SELF
+ },
+ .out = {
+ .nr_extents = extents_out,
+ .extent_order = order_out,
+ .address_bits = address_bits,
+ .domid = DOMID_SELF
+ }
+ };
+ set_xen_guest_handle(exchange.in.extent_start, pfns_in);
+ set_xen_guest_handle(exchange.out.extent_start, mfns_out);
+
+ BUG_ON(extents_in << order_in != extents_out << order_out);
+
+
+ rc = HYPERVISOR_memory_op(XENMEM_exchange_and_pin, &exchange);
+ success = (exchange.nr_exchanged == extents_in);
+
+ BUG_ON(!success && ((exchange.nr_exchanged != 0) || (rc == 0)));
+ BUG_ON(success && (rc != 0));
+
+ return success;
+}
+
+int xen_create_contiguous_region(unsigned long vstart, 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;
+
+ /* Get a new contiguous memory extent. */
+ in_frame = out_frame = pstart >> PAGE_SHIFT;
+ success = xen_exchange_memory(1, order, &in_frame,
+ 1, order, &out_frame,
+ address_bits);
+
+ if (!success)
+ return -ENOMEM;
+
+ *dma_handle = out_frame << PAGE_SHIFT;
+
+ return success ? 0 : -ENOMEM;
+}
+EXPORT_SYMBOL_GPL(xen_create_contiguous_region);
+
+void xen_destroy_contiguous_region(unsigned long vstart, unsigned int order)
+{
+ xen_pfn_t in_frame = __pa(vstart) >> PAGE_SHIFT;
+ struct xen_unpin unpin = {
+ .in = {
+ .nr_extents = 1,
+ .extent_order = order,
+ .domid = DOMID_SELF
+ },
+ };
+ set_xen_guest_handle(unpin.in.extent_start, &in_frame);
+
+ WARN_ON(HYPERVISOR_memory_op(XENMEM_unpin, &unpin));
+}
+EXPORT_SYMBOL_GPL(xen_destroy_contiguous_region);
+
+struct dma_map_ops *xen_dma_ops;
+EXPORT_SYMBOL_GPL(xen_dma_ops);
+
+static struct dma_map_ops xen_swiotlb_dma_ops = {
+ .mapping_error = xen_swiotlb_dma_mapping_error,
+ .alloc = xen_swiotlb_alloc_coherent,
+ .free = xen_swiotlb_free_coherent,
+ .sync_single_for_cpu = xen_swiotlb_sync_single_for_cpu,
+ .sync_single_for_device = xen_swiotlb_sync_single_for_device,
+ .sync_sg_for_cpu = xen_swiotlb_sync_sg_for_cpu,
+ .sync_sg_for_device = xen_swiotlb_sync_sg_for_device,
+ .map_sg = xen_swiotlb_map_sg_attrs,
+ .unmap_sg = xen_swiotlb_unmap_sg_attrs,
+ .map_page = xen_swiotlb_map_page,
+ .unmap_page = xen_swiotlb_unmap_page,
+ .dma_supported = xen_swiotlb_dma_supported,
+};
+
+int __init xen_mm_init(void)
+{
+ xen_swiotlb_init(1, false);
+ xen_dma_ops = &xen_swiotlb_dma_ops;
+ return 0;
+}
+arch_initcall(xen_mm_init);
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 9737e97..aa1f6fb 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -209,6 +209,7 @@ config XEN_DOM0
config XEN
bool "Xen guest support on ARM64 (EXPERIMENTAL)"
depends on ARM64 && OF
+ select SWIOTLB_XEN
help
Say Y if you want to run Linux in a Virtual Machine on Xen on ARM64.

diff --git a/arch/arm64/xen/Makefile b/arch/arm64/xen/Makefile
index be24040..0ef9637 100644
--- a/arch/arm64/xen/Makefile
+++ b/arch/arm64/xen/Makefile
@@ -1,2 +1,2 @@
-xen-arm-y += $(addprefix ../../arm/xen/, enlighten.o grant-table.o)
+xen-arm-y += $(addprefix ../../arm/xen/, enlighten.o grant-table.o mm.o)
obj-y := xen-arm.o hypercall.o
diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index 9e02d60..7e83688 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -140,7 +140,6 @@ config XEN_GRANT_DEV_ALLOC

config SWIOTLB_XEN
def_bool y
- depends on PCI && X86
select SWIOTLB

config XEN_TMEM
diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 84aef43..a1cb0f4 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -45,6 +45,8 @@
#include <xen/xen-ops.h>
#include <xen/hvc-console.h>
#include <xen/features.h>
+#include <asm/dma-mapping.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
@@ -58,6 +60,20 @@ static unsigned long xen_io_tlb_nslabs;
* Quick lookup value of the bus address of the IOTLB.
*/

+#ifndef CONFIG_X86
+static unsigned long dma_alloc_coherent_mask(struct device *dev,
+ gfp_t gfp)
+{
+ unsigned long dma_mask = 0;
+
+ dma_mask = dev->coherent_dma_mask;
+ if (!dma_mask)
+ dma_mask = (gfp & GFP_DMA) ? DMA_BIT_MASK(24) : DMA_BIT_MASK(32);
+
+ return dma_mask;
+}
+#endif
+
struct xen_dma_info {
dma_addr_t dma_addr;
phys_addr_t phys_addr;
--
1.7.2.5


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