- 根目录:
- drivers
- xen
- swiotlb-xen.c
/*
* 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;
unsigned long nr_tbl;
nr_tbl = swioltb_nr_tbl();
if (nr_tbl)
xen_io_tlb_nslabs = nr_tbl;
else {
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_pages(PAGE_ALIGN(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)) {
swiotlb_tbl_unmap_single(dev, map, size, dir);
dev_addr = 0;
}
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);