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SubjectRe: [PATCH 1/9] xen: make sure swiotlb allocation is physically contigious
On Thu, May 07, 2009 at 05:17:14PM -0700, Jeremy Fitzhardinge wrote:
> Impact: make swiotlb allocation suitable for Xen
>
> When allocating the swiotlb buffer under Xen, make sure the memory is
> physically contiguous so that its really suitable for DMA.
>
> Do this by allocating the memory as usual, but then call a Xen
> function to rearrange the underlying pages to be physically
> contiguous.
>
> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
> Reviewed-by: "H. Peter Anvin" <hpa@zytor.com>
> Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
> ---
> arch/x86/kernel/pci-swiotlb.c | 10 ----------
> arch/x86/xen/Makefile | 1 +
> arch/x86/xen/pci-swiotlb.c | 27 +++++++++++++++++++++++++++
> drivers/pci/xen-iommu.c | 16 ++++++++++++++++
> include/xen/swiotlb.h | 6 ++++++
> 5 files changed, 50 insertions(+), 10 deletions(-)
> create mode 100644 arch/x86/xen/pci-swiotlb.c
> create mode 100644 include/xen/swiotlb.h
>
> diff --git a/arch/x86/kernel/pci-swiotlb.c b/arch/x86/kernel/pci-swiotlb.c
> index 34f12e9..bc09da7 100644
> --- a/arch/x86/kernel/pci-swiotlb.c
> +++ b/arch/x86/kernel/pci-swiotlb.c
> @@ -13,16 +13,6 @@
>
> int swiotlb __read_mostly;
>
> -void * __init swiotlb_alloc_boot(size_t size, unsigned long nslabs)
> -{
> - return alloc_bootmem_low_pages(size);
> -}
> -
> -void *swiotlb_alloc(unsigned order, unsigned long nslabs)
> -{
> - return (void *)__get_free_pages(GFP_DMA | __GFP_NOWARN, order);
> -}
> -
> dma_addr_t swiotlb_phys_to_bus(struct device *hwdev, phys_addr_t paddr)
> {
> return paddr;
> diff --git a/arch/x86/xen/Makefile b/arch/x86/xen/Makefile
> index c4cda96..caede49 100644
> --- a/arch/x86/xen/Makefile
> +++ b/arch/x86/xen/Makefile
> @@ -12,3 +12,4 @@ obj-y := enlighten.o setup.o multicalls.o mmu.o irq.o \
> obj-$(CONFIG_SMP) += smp.o spinlock.o
> obj-$(CONFIG_XEN_DEBUG_FS) += debugfs.o
> obj-$(CONFIG_XEN_DOM0) += vga.o
> +obj-$(CONFIG_PCI_XEN) += pci-swiotlb.o
> \ No newline at end of file
> diff --git a/arch/x86/xen/pci-swiotlb.c b/arch/x86/xen/pci-swiotlb.c
> new file mode 100644
> index 0000000..25f0365
> --- /dev/null
> +++ b/arch/x86/xen/pci-swiotlb.c
> @@ -0,0 +1,27 @@
> +#include <linux/bootmem.h>
> +#include <linux/gfp.h>
> +
> +#include <xen/swiotlb.h>
> +#include <asm/xen/hypervisor.h>
> +
> +/*
> + * This file defines overrides for weak functions with default
> + * implementations in lib/swiotlb.c.
> + */
> +
> +void * __init swiotlb_alloc_boot(size_t size, unsigned long nslabs)
> +{
> + void *ret = alloc_bootmem_low_pages(size);
> +
> + if (ret && xen_pv_domain())
> + xen_swiotlb_fixup(ret, size, nslabs);
> +
> + return ret;
> +}
> +
> +void *swiotlb_alloc(unsigned order, unsigned long nslabs)
> +{
> + /* Never called on x86. Warn, just in case. */

Can't this function be removed completly then?

> + WARN_ON(1);
> + return NULL;
> +}
> diff --git a/drivers/pci/xen-iommu.c b/drivers/pci/xen-iommu.c
> index 32a8b49..c593058 100644
> --- a/drivers/pci/xen-iommu.c
> +++ b/drivers/pci/xen-iommu.c
> @@ -12,6 +12,7 @@
> #include <xen/grant_table.h>
> #include <xen/page.h>
> #include <xen/xen-ops.h>
> +#include <xen/swiotlb.h>
>
> #include <asm/iommu.h>
> #include <asm/swiotlb.h>
> @@ -34,6 +35,21 @@ do { \
> (unsigned long long)addr + size); \
> } while (0)
>
> +
> +void xen_swiotlb_fixup(void *buf, size_t size, unsigned long nslabs)
> +{
> + unsigned order = get_order(size);
> +
> + printk(KERN_DEBUG "xen_swiotlb_fixup: buf=%p size=%zu order=%u\n",
> + buf, size, order);
> +
> + if (WARN_ON(size != (PAGE_SIZE << order)))
> + return;
> +
> + if (xen_create_contiguous_region((unsigned long)buf,
> + order, 0xffffffff))
DMA_32BIT_MASK?

> + printk(KERN_ERR "xen_create_contiguous_region failed\n");
> +}
> static inline int address_needs_mapping(struct device *hwdev,
> dma_addr_t addr)
> {
> diff --git a/include/xen/swiotlb.h b/include/xen/swiotlb.h
> new file mode 100644
> index 0000000..67b7b42
> --- /dev/null
> +++ b/include/xen/swiotlb.h
> @@ -0,0 +1,6 @@
> +#ifndef _XEN_SWIOTLB_H
> +#define _XEN_SWIOTLB_H
> +
> +extern void xen_swiotlb_fixup(void *buf, size_t size, unsigned long nslabs);
> +
> +#endif /* _XEN_SWIOTLB_H */
> --
> 1.6.0.6
>
> --
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