swiotlb-xen: SWIOTLB library for Xen PV guest with PCI passthrough. (b097186f) · Commits · 戴 / test

drivers/xen/Kconfig

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Original line number	Diff line number	Diff line
		@@ -62,4 +62,8 @@ config XEN_SYS_HYPERVISOR
		virtual environment, /sys/hypervisor will still be present,
		but will have no xen contents.

		config SWIOTLB_XEN
		def_bool y
		depends on SWIOTLB

		endmenu

drivers/xen/Makefile

+2 −1

Original line number	Diff line number	Diff line
		@@ -10,3 +10,4 @@ obj-$(CONFIG_XEN_BALLOON) += balloon.o
		obj-$(CONFIG_XEN_DEV_EVTCHN) += evtchn.o
		obj-$(CONFIG_XENFS) += xenfs/
		obj-$(CONFIG_XEN_SYS_HYPERVISOR) += sys-hypervisor.o
		obj-$(CONFIG_SWIOTLB_XEN) += swiotlb-xen.o

drivers/xen/swiotlb-xen.c

0 → 100644

+515 −0

Original line number	Diff line number	Diff line
		/*
		* Copyright 2010
		* by Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
		*
		* This code provides a IOMMU for Xen PV guests with PCI passthrough.
		*
		* This program is free software; you can redistribute it and/or modify
		* it under the terms of the GNU General Public License v2.0 as published by
		* the Free Software Foundation
		*
		* This program is distributed in the hope that it will be useful,
		* but WITHOUT ANY WARRANTY; without even the implied warranty of
		* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
		* GNU General Public License for more details.
		*
		* PV guests under Xen are running in an non-contiguous memory architecture.
		*
		* When PCI pass-through is utilized, this necessitates an IOMMU for
		* translating bus (DMA) to virtual and vice-versa and also providing a
		* mechanism to have contiguous pages for device drivers operations (say DMA
		* operations).
		*
		* Specifically, under Xen the Linux idea of pages is an illusion. It
		* assumes that pages start at zero and go up to the available memory. To
		* help with that, the Linux Xen MMU provides a lookup mechanism to
		* translate the page frame numbers (PFN) to machine frame numbers (MFN)
		* and vice-versa. The MFN are the "real" frame numbers. Furthermore
		* memory is not contiguous. Xen hypervisor stitches memory for guests
		* from different pools, which means there is no guarantee that PFN==MFN
		* and PFN+1==MFN+1. Lastly with Xen 4.0, pages (in debug mode) are
		* allocated in descending order (high to low), meaning the guest might
		* never get any MFN's under the 4GB mark.
		*
		*/

		#include <linux/bootmem.h>
		#include <linux/dma-mapping.h>
		#include <xen/swiotlb-xen.h>
		#include <xen/page.h>
		#include <xen/xen-ops.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
		* API.
		*/

		static char xen_io_tlb_start, xen_io_tlb_end;
		static unsigned long xen_io_tlb_nslabs;
		/*
		* Quick lookup value of the bus address of the IOTLB.
		*/

		u64 start_dma_addr;

		static dma_addr_t xen_phys_to_bus(phys_addr_t paddr)
		{
		return phys_to_machine(XPADDR(paddr)).maddr;;
		}

		static phys_addr_t xen_bus_to_phys(dma_addr_t baddr)
		{
		return machine_to_phys(XMADDR(baddr)).paddr;
		}

		static dma_addr_t xen_virt_to_bus(void *address)
		{
		return xen_phys_to_bus(virt_to_phys(address));
		}

		static int check_pages_physically_contiguous(unsigned long pfn,
		unsigned int offset,
		size_t length)
		{
		unsigned long next_mfn;
		int i;
		int nr_pages;

		next_mfn = pfn_to_mfn(pfn);
		nr_pages = (offset + length + PAGE_SIZE-1) >> PAGE_SHIFT;

		for (i = 1; i < nr_pages; i++) {
		if (pfn_to_mfn(++pfn) != ++next_mfn)
		return 0;
		}
		return 1;
		}

		static int range_straddles_page_boundary(phys_addr_t p, size_t size)
		{
		unsigned long pfn = PFN_DOWN(p);
		unsigned int offset = p & ~PAGE_MASK;

		if (offset + size <= PAGE_SIZE)
		return 0;
		if (check_pages_physically_contiguous(pfn, offset, size))
		return 0;
		return 1;
		}

		static int is_xen_swiotlb_buffer(dma_addr_t dma_addr)
		{
		unsigned long mfn = PFN_DOWN(dma_addr);
		unsigned long pfn = mfn_to_local_pfn(mfn);
		phys_addr_t paddr;

		/* If the address is outside our domain, it CAN
		* have the same virtual address as another address
		* in our domain. Therefore _only_ check address within our domain.
		*/
		if (pfn_valid(pfn)) {
		paddr = PFN_PHYS(pfn);
		return paddr >= virt_to_phys(xen_io_tlb_start) &&
		paddr < virt_to_phys(xen_io_tlb_end);
		}
		return 0;
		}

		static int max_dma_bits = 32;

		static int
		xen_swiotlb_fixup(void *buf, size_t size, unsigned long nslabs)
		{
		int i, rc;
		int dma_bits;

		dma_bits = get_order(IO_TLB_SEGSIZE << IO_TLB_SHIFT) + PAGE_SHIFT;

		i = 0;
		do {
		int slabs = min(nslabs - i, (unsigned long)IO_TLB_SEGSIZE);

		do {
		rc = xen_create_contiguous_region(
		(unsigned long)buf + (i << IO_TLB_SHIFT),
		get_order(slabs << IO_TLB_SHIFT),
		dma_bits);
		} while (rc && dma_bits++ < max_dma_bits);
		if (rc)
		return rc;

		i += slabs;
		} while (i < nslabs);
		return 0;
		}

		void __init xen_swiotlb_init(int verbose)
		{
		unsigned long bytes;
		int rc;

		xen_io_tlb_nslabs = (64 * 1024 * 1024 >> IO_TLB_SHIFT);
		xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs, IO_TLB_SEGSIZE);

		bytes = xen_io_tlb_nslabs << IO_TLB_SHIFT;

		/*
		* Get IO TLB memory from any location.
		*/
		xen_io_tlb_start = alloc_bootmem(bytes);
		if (!xen_io_tlb_start)
		panic("Cannot allocate SWIOTLB buffer");

		xen_io_tlb_end = xen_io_tlb_start + bytes;
		/*
		* And replace that memory with pages under 4GB.
		*/
		rc = xen_swiotlb_fixup(xen_io_tlb_start,
		bytes,
		xen_io_tlb_nslabs);
		if (rc)
		goto error;

		start_dma_addr = xen_virt_to_bus(xen_io_tlb_start);
		swiotlb_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs, verbose);

		return;
		error:
		panic("DMA(%d): Failed to exchange pages allocated for DMA with Xen! "\
		"We either don't have the permission or you do not have enough"\
		"free memory under 4GB!\n", rc);
		}

		void *
		xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
		dma_addr_t *dma_handle, gfp_t flags)
		{
		void *ret;
		int order = get_order(size);
		u64 dma_mask = DMA_BIT_MASK(32);
		unsigned long vstart;

		/*
		* Ignore region specifiers - the kernel's ideas of
		* pseudo-phys memory layout has nothing to do with the
		* machine physical layout. We can't allocate highmem
		* because we can't return a pointer to it.
		*/
		flags &= ~(__GFP_DMA \| __GFP_HIGHMEM);

		if (dma_alloc_from_coherent(hwdev, size, dma_handle, &ret))
		return ret;

		vstart = __get_free_pages(flags, order);
		ret = (void *)vstart;

		if (hwdev && hwdev->coherent_dma_mask)
		dma_mask = dma_alloc_coherent_mask(hwdev, flags);

		if (ret) {
		if (xen_create_contiguous_region(vstart, order,
		fls64(dma_mask)) != 0) {
		free_pages(vstart, order);
		return NULL;
		}
		memset(ret, 0, size);
		*dma_handle = virt_to_machine(ret).maddr;
		}
		return ret;
		}
		EXPORT_SYMBOL_GPL(xen_swiotlb_alloc_coherent);

		void
		xen_swiotlb_free_coherent(struct device hwdev, size_t size, void vaddr,
		dma_addr_t dev_addr)
		{
		int order = get_order(size);

		if (dma_release_from_coherent(hwdev, order, vaddr))
		return;

		xen_destroy_contiguous_region((unsigned long)vaddr, order);
		free_pages((unsigned long)vaddr, order);
		}
		EXPORT_SYMBOL_GPL(xen_swiotlb_free_coherent);


		/*
		* Map a single buffer of the indicated size for DMA in streaming mode. The
		* physical address to use is returned.
		*
		* Once the device is given the dma address, the device owns this memory until
		* either xen_swiotlb_unmap_page or xen_swiotlb_dma_sync_single is performed.
		*/
		dma_addr_t xen_swiotlb_map_page(struct device dev, struct page page,
		unsigned long offset, size_t size,
		enum dma_data_direction dir,
		struct dma_attrs *attrs)
		{
		phys_addr_t phys = page_to_phys(page) + offset;
		dma_addr_t dev_addr = xen_phys_to_bus(phys);
		void *map;

		BUG_ON(dir == DMA_NONE);
		/*
		* If the address happens to be in the device's DMA window,
		* we can safely return the device addr and not worry about bounce
		* buffering it.
		*/
		if (dma_capable(dev, dev_addr, size) &&
		!range_straddles_page_boundary(phys, size) && !swiotlb_force)
		return dev_addr;

		/*
		* Oh well, have to allocate and map a bounce buffer.
		*/
		map = swiotlb_tbl_map_single(dev, start_dma_addr, phys, size, dir);
		if (!map)
		return DMA_ERROR_CODE;

		dev_addr = xen_virt_to_bus(map);

		/*
		* Ensure that the address returned is DMA'ble
		*/
		if (!dma_capable(dev, dev_addr, size))
		panic("map_single: bounce buffer is not DMA'ble");

		return dev_addr;
		}
		EXPORT_SYMBOL_GPL(xen_swiotlb_map_page);

		/*
		* Unmap a single streaming mode DMA translation. The dma_addr and size must
		* match what was provided for in a previous xen_swiotlb_map_page call. All
		* other usages are undefined.
		*
		* After this call, reads by the cpu to the buffer are guaranteed to see
		* whatever the device wrote there.
		*/
		static void xen_unmap_single(struct device *hwdev, dma_addr_t dev_addr,
		size_t size, enum dma_data_direction dir)
		{
		phys_addr_t paddr = xen_bus_to_phys(dev_addr);

		BUG_ON(dir == DMA_NONE);

		/* NOTE: We use dev_addr here, not paddr! */
		if (is_xen_swiotlb_buffer(dev_addr)) {
		swiotlb_tbl_unmap_single(hwdev, phys_to_virt(paddr), size, dir);
		return;
		}

		if (dir != DMA_FROM_DEVICE)
		return;

		/*
		* phys_to_virt doesn't work with hihgmem page but we could
		* call dma_mark_clean() with hihgmem page here. However, we
		* are fine since dma_mark_clean() is null on POWERPC. We can
		* make dma_mark_clean() take a physical address if necessary.
		*/
		dma_mark_clean(phys_to_virt(paddr), size);
		}

		void xen_swiotlb_unmap_page(struct device *hwdev, dma_addr_t dev_addr,
		size_t size, enum dma_data_direction dir,
		struct dma_attrs *attrs)
		{
		xen_unmap_single(hwdev, dev_addr, size, dir);
		}
		EXPORT_SYMBOL_GPL(xen_swiotlb_unmap_page);

		/*
		* Make physical memory consistent for a single streaming mode DMA translation
		* after a transfer.
		*
		* If you perform a xen_swiotlb_map_page() but wish to interrogate the buffer
		* using the cpu, yet do not wish to teardown the dma mapping, you must
		* call this function before doing so. At the next point you give the dma
		* address back to the card, you must first perform a
		* xen_swiotlb_dma_sync_for_device, and then the device again owns the buffer
		*/
		static void
		xen_swiotlb_sync_single(struct device *hwdev, dma_addr_t dev_addr,
		size_t size, enum dma_data_direction dir,
		enum dma_sync_target target)
		{
		phys_addr_t paddr = xen_bus_to_phys(dev_addr);

		BUG_ON(dir == DMA_NONE);

		/* NOTE: We use dev_addr here, not paddr! */
		if (is_xen_swiotlb_buffer(dev_addr)) {
		swiotlb_tbl_sync_single(hwdev, phys_to_virt(paddr), size, dir,
		target);
		return;
		}

		if (dir != DMA_FROM_DEVICE)
		return;

		dma_mark_clean(phys_to_virt(paddr), size);
		}

		void
		xen_swiotlb_sync_single_for_cpu(struct device *hwdev, dma_addr_t dev_addr,
		size_t size, enum dma_data_direction dir)
		{
		xen_swiotlb_sync_single(hwdev, dev_addr, size, dir, SYNC_FOR_CPU);
		}
		EXPORT_SYMBOL_GPL(xen_swiotlb_sync_single_for_cpu);

		void
		xen_swiotlb_sync_single_for_device(struct device *hwdev, dma_addr_t dev_addr,
		size_t size, enum dma_data_direction dir)
		{
		xen_swiotlb_sync_single(hwdev, dev_addr, size, dir, SYNC_FOR_DEVICE);
		}
		EXPORT_SYMBOL_GPL(xen_swiotlb_sync_single_for_device);

		/*
		* Map a set of buffers described by scatterlist in streaming mode for DMA.
		* This is the scatter-gather version of the above xen_swiotlb_map_page
		* interface. Here the scatter gather list elements are each tagged with the
		* appropriate dma address and length. They are obtained via
		* sg_dma_{address,length}(SG).
		*
		* NOTE: An implementation may be able to use a smaller number of
		* DMA address/length pairs than there are SG table elements.
		* (for example via virtual mapping capabilities)
		* The routine returns the number of addr/length pairs actually
		* used, at most nents.
		*
		* Device ownership issues as mentioned above for xen_swiotlb_map_page are the
		* same here.
		*/
		int
		xen_swiotlb_map_sg_attrs(struct device hwdev, struct scatterlist sgl,
		int nelems, enum dma_data_direction dir,
		struct dma_attrs *attrs)
		{
		struct scatterlist *sg;
		int i;

		BUG_ON(dir == DMA_NONE);

		for_each_sg(sgl, sg, nelems, i) {
		phys_addr_t paddr = sg_phys(sg);
		dma_addr_t dev_addr = xen_phys_to_bus(paddr);

		if (swiotlb_force \|\|
		!dma_capable(hwdev, dev_addr, sg->length) \|\|
		range_straddles_page_boundary(paddr, sg->length)) {
		void *map = swiotlb_tbl_map_single(hwdev,
		start_dma_addr,
		sg_phys(sg),
		sg->length, dir);
		if (!map) {
		/* Don't panic here, we expect map_sg users
		to do proper error handling. */
		xen_swiotlb_unmap_sg_attrs(hwdev, sgl, i, dir,
		attrs);
		sgl[0].dma_length = 0;
		return DMA_ERROR_CODE;
		}
		sg->dma_address = xen_virt_to_bus(map);
		} else
		sg->dma_address = dev_addr;
		sg->dma_length = sg->length;
		}
		return nelems;
		}
		EXPORT_SYMBOL_GPL(xen_swiotlb_map_sg_attrs);

		int
		xen_swiotlb_map_sg(struct device hwdev, struct scatterlist sgl, int nelems,
		enum dma_data_direction dir)
		{
		return xen_swiotlb_map_sg_attrs(hwdev, sgl, nelems, dir, NULL);
		}
		EXPORT_SYMBOL_GPL(xen_swiotlb_map_sg);

		/*
		* Unmap a set of streaming mode DMA translations. Again, cpu read rules
		* concerning calls here are the same as for swiotlb_unmap_page() above.
		*/
		void
		xen_swiotlb_unmap_sg_attrs(struct device hwdev, struct scatterlist sgl,
		int nelems, enum dma_data_direction dir,
		struct dma_attrs *attrs)
		{
		struct scatterlist *sg;
		int i;

		BUG_ON(dir == DMA_NONE);

		for_each_sg(sgl, sg, nelems, i)
		xen_unmap_single(hwdev, sg->dma_address, sg->dma_length, dir);

		}
		EXPORT_SYMBOL_GPL(xen_swiotlb_unmap_sg_attrs);

		void
		xen_swiotlb_unmap_sg(struct device hwdev, struct scatterlist sgl, int nelems,
		enum dma_data_direction dir)
		{
		return xen_swiotlb_unmap_sg_attrs(hwdev, sgl, nelems, dir, NULL);
		}
		EXPORT_SYMBOL_GPL(xen_swiotlb_unmap_sg);

		/*
		* Make physical memory consistent for a set of streaming mode DMA translations
		* after a transfer.
		*
		* The same as swiotlb_sync_single_* but for a scatter-gather list, same rules
		* and usage.
		*/
		static void
		xen_swiotlb_sync_sg(struct device hwdev, struct scatterlist sgl,
		int nelems, enum dma_data_direction dir,
		enum dma_sync_target target)
		{
		struct scatterlist *sg;
		int i;

		for_each_sg(sgl, sg, nelems, i)
		xen_swiotlb_sync_single(hwdev, sg->dma_address,
		sg->dma_length, dir, target);
		}

		void
		xen_swiotlb_sync_sg_for_cpu(struct device hwdev, struct scatterlist sg,
		int nelems, enum dma_data_direction dir)
		{
		xen_swiotlb_sync_sg(hwdev, sg, nelems, dir, SYNC_FOR_CPU);
		}
		EXPORT_SYMBOL_GPL(xen_swiotlb_sync_sg_for_cpu);

		void
		xen_swiotlb_sync_sg_for_device(struct device hwdev, struct scatterlist sg,
		int nelems, enum dma_data_direction dir)
		{
		xen_swiotlb_sync_sg(hwdev, sg, nelems, dir, SYNC_FOR_DEVICE);
		}
		EXPORT_SYMBOL_GPL(xen_swiotlb_sync_sg_for_device);

		int
		xen_swiotlb_dma_mapping_error(struct device *hwdev, dma_addr_t dma_addr)
		{
		return !dma_addr;
		}
		EXPORT_SYMBOL_GPL(xen_swiotlb_dma_mapping_error);

		/*
		* Return whether the given device DMA address mask can be supported
		* properly. For example, if your device can only drive the low 24-bits
		* during bus mastering, then you would pass 0x00ffffff as the mask to
		* this function.
		*/
		int
		xen_swiotlb_dma_supported(struct device *hwdev, u64 mask)
		{
		return xen_virt_to_bus(xen_io_tlb_end - 1) <= mask;
		}
		EXPORT_SYMBOL_GPL(xen_swiotlb_dma_supported);

include/xen/swiotlb-xen.h

0 → 100644

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Original line number	Diff line number	Diff line
		#ifndef __LINUX_SWIOTLB_XEN_H
		#define __LINUX_SWIOTLB_XEN_H

		#include <linux/swiotlb.h>

		extern void xen_swiotlb_init(int verbose);

		extern void
		xen_swiotlb_alloc_coherent(struct device hwdev, size_t size,
		dma_addr_t *dma_handle, gfp_t flags);

		extern void
		xen_swiotlb_free_coherent(struct device *hwdev, size_t size,
		void *vaddr, dma_addr_t dma_handle);

		extern dma_addr_t xen_swiotlb_map_page(struct device dev, struct page page,
		unsigned long offset, size_t size,
		enum dma_data_direction dir,
		struct dma_attrs *attrs);

		extern void xen_swiotlb_unmap_page(struct device *hwdev, dma_addr_t dev_addr,
		size_t size, enum dma_data_direction dir,
		struct dma_attrs *attrs);
		/*
		extern int
		xen_swiotlb_map_sg(struct device hwdev, struct scatterlist sg, int nents,
		enum dma_data_direction dir);

		extern void
		xen_swiotlb_unmap_sg(struct device hwdev, struct scatterlist sg, int nents,
		enum dma_data_direction dir);
		*/
		extern int
		xen_swiotlb_map_sg_attrs(struct device hwdev, struct scatterlist sgl,
		int nelems, enum dma_data_direction dir,
		struct dma_attrs *attrs);

		extern void
		xen_swiotlb_unmap_sg_attrs(struct device hwdev, struct scatterlist sgl,
		int nelems, enum dma_data_direction dir,
		struct dma_attrs *attrs);

		extern void
		xen_swiotlb_sync_single_for_cpu(struct device *hwdev, dma_addr_t dev_addr,
		size_t size, enum dma_data_direction dir);

		extern void
		xen_swiotlb_sync_sg_for_cpu(struct device hwdev, struct scatterlist sg,
		int nelems, enum dma_data_direction dir);

		extern void
		xen_swiotlb_sync_single_for_device(struct device *hwdev, dma_addr_t dev_addr,
		size_t size, enum dma_data_direction dir);

		extern void
		xen_swiotlb_sync_sg_for_device(struct device hwdev, struct scatterlist sg,
		int nelems, enum dma_data_direction dir);

		extern int
		xen_swiotlb_dma_mapping_error(struct device *hwdev, dma_addr_t dma_addr);

		extern int
		xen_swiotlb_dma_supported(struct device *hwdev, u64 mask);

		#endif /* __LINUX_SWIOTLB_XEN_H */

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