/*
* 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.
*
*/
#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
#include <linux/memblock.h>
#include <linux/dma-direct.h>
#include <linux/export.h>
#include <xen/swiotlb-xen.h>
#include <xen/page.h>
#include <xen/xen-ops.h>
#include <xen/hvc-console.h>
#include <asm/dma-mapping.h>
#include <asm/xen/page-coherent.h>
#include <trace/events/swiotlb.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.
*/
static u64 start_dma_addr;
/*
* Both of these functions should avoid XEN_PFN_PHYS because phys_addr_t
* can be 32bit when dma_addr_t is 64bit leading to a loss in
* information if the shift is done before casting to 64bit.
*/
static inline dma_addr_t xen_phys_to_bus(phys_addr_t paddr)
{
unsigned long bfn = pfn_to_bfn(XEN_PFN_DOWN(paddr));
dma_addr_t dma = (dma_addr_t)bfn << XEN_PAGE_SHIFT;
dma |= paddr & ~XEN_PAGE_MASK;
return dma;
}
static inline phys_addr_t xen_bus_to_phys(dma_addr_t baddr)
{
unsigned long xen_pfn = bfn_to_pfn(XEN_PFN_DOWN(baddr));
dma_addr_t dma = (dma_addr_t)xen_pfn << XEN_PAGE_SHIFT;
phys_addr_t paddr = dma;
paddr |= baddr & ~XEN_PAGE_MASK;
return paddr;
}
static inline 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 xen_pfn,
unsigned int offset,
size_t length)
{
unsigned long next_bfn;
int i;
int nr_pages;
next_bfn = pfn_to_bfn(xen_pfn);
nr_pages = (offset + length + XEN_PAGE_SIZE-1) >> XEN_PAGE_SHIFT;
for (i = 1; i < nr_pages; i++) {
if (pfn_to_bfn(++xen_pfn) != ++next_bfn)
return 0;
}
return 1;
}
static inline int range_straddles_page_boundary(phys_addr_t p, size_t size)
{
unsigned long xen_pfn = XEN_PFN_DOWN(p);
unsigned int offset = p & ~XEN_PAGE_MASK;
if (offset + size <= XEN_PAGE_SIZE)
return 0;
if (check_pages_physically_contiguous(xen_pfn, offset, size))
return 0;
return 1;
}
static int is_xen_swiotlb_buffer(dma_addr_t dma_addr)
{
unsigned long bfn = XEN_PFN_DOWN(dma_addr);
unsigned long xen_pfn = bfn_to_local_pfn(bfn);
phys_addr_t paddr = XEN_PFN_PHYS(xen_pfn);
/* 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_DOWN(paddr))) {
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_addr_t dma_handle;
phys_addr_t p = virt_to_phys(buf);
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(
p + (i << IO_TLB_SHIFT),
get_order(slabs << IO_TLB_SHIFT),
dma_bits, &dma_handle);
} while (rc && dma_bits++ < max_dma_bits);
if (rc)
return rc;
i += slabs;
} while (i < nslabs);
return 0;
}
static unsigned long xen_set_nslabs(unsigned long nr_tbl)
{
if (!nr_tbl) {
xen_io_tlb_nslabs = (64 * 1024 * 1024 >> IO_TLB_SHIFT);
xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs, IO_TLB_SEGSIZE);
} else
xen_io_tlb_nslabs = nr_tbl;
return xen_io_tlb_nslabs << IO_TLB_SHIFT;
}
enum xen_swiotlb_err {
XEN_SWIOTLB_UNKNOWN = 0,
XEN_SWIOTLB_ENOMEM,
XEN_SWIOTLB_EFIXUP
};
static const char *xen_swiotlb_error(enum xen_swiotlb_err err)
{
switch (err) {
case XEN_SWIOTLB_ENOMEM:
return "Cannot allocate Xen-SWIOTLB buffer\n";
case XEN_SWIOTLB_EFIXUP:
return "Failed to get contiguous memory for DMA from Xen!\n"\
"You either: don't have the permissions, do not have"\
" enough free memory under 4GB, or the hypervisor memory"\
" is too fragmented!";
default:
break;
}
return "";
}
int __ref xen_swiotlb_init(int verbose, bool early)
{
unsigned long bytes, order;
int rc = -ENOMEM;
enum xen_swiotlb_err m_ret = XEN_SWIOTLB_UNKNOWN;
unsigned int repeat = 3;
xen_io_tlb_nslabs = swiotlb_nr_tbl();
retry:
bytes = xen_set_nslabs(xen_io_tlb_nslabs);
order = get_order(xen_io_tlb_nslabs << IO_TLB_SHIFT);
/*
* Get IO TLB memory from any location.
*/
if (early)
xen_io_tlb_start = memblock_alloc(PAGE_ALIGN(bytes),
PAGE_SIZE);
else {
#define SLABS_PER_PAGE (1 << (PAGE_SHIFT - IO_TLB_SHIFT))
#define IO_TLB_MIN_SLABS ((1<<20) >> IO_TLB_SHIFT)
while ((SLABS_PER_PAGE << order) > IO_TLB_MIN_SLABS) {
xen_io_tlb_start = (void *)xen_get_swiotlb_free_pages(order);
if (xen_io_tlb_start)
break;
order--;
}
if (order != get_order(bytes)) {
pr_warn("Warning: only able to allocate %ld MB for software IO TLB\n",
(PAGE_SIZE << order) >> 20);
xen_io_tlb_nslabs = SLABS_PER_PAGE << order;
bytes = xen_io_tlb_nslabs << IO_TLB_SHIFT;
}
}
if (!xen_io_tlb_start) {
m_ret = XEN_SWIOTLB_ENOMEM;
goto error;
}
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) {
if (early)
memblock_free(__pa(xen_io_tlb_start),
PAGE_ALIGN(bytes));
else {
free_pages((unsigned long)xen_io_tlb_start, order);
xen_io_tlb_start = NULL;
}
m_ret = XEN_SWIOTLB_EFIXUP;
goto error;
}
start_dma_addr = xen_virt_to_bus(xen_io_tlb_start);
if (early) {
if (swiotlb_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs,
verbose))
panic("Cannot allocate SWIOTLB buffer");
rc = 0;
} else
rc = swiotlb_late_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs);
if (!rc)
swiotlb_set_max_segment(PAGE_SIZE);
return rc;
error:
if (repeat--) {
xen_io_tlb_nslabs = max(1024UL, /* Min is 2MB */
(xen_io_tlb_nslabs >> 1));
pr_info("Lowering to %luMB\n",
(xen_io_tlb_nslabs << IO_TLB_SHIFT) >> 20);
goto retry;
}
pr_err("%s (rc:%d)\n", xen_swiotlb_error(m_ret), rc);
if (early)
panic("%s (rc:%d)", xen_swiotlb_error(m_ret), rc);
else
free_pages((unsigned long)xen_io_tlb_start, order);
return rc;
}
static void *
xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
dma_addr_t *dma_handle, gfp_t flags,
unsigned long attrs)
{
void *ret;
int order = get_order(size);
u64 dma_mask = DMA_BIT_MASK(32);
phys_addr_t phys;
dma_addr_t dev_addr;
/*
* 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);
/* Convert the size to actually allocated. */
size = 1UL << (order + XEN_PAGE_SHIFT);
/* 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;
if (hwdev && hwdev->coherent_dma_mask)
dma_mask = hwdev->coherent_dma_mask;
/* 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 (((dev_addr + size - 1 <= dma_mask)) &&
!range_straddles_page_boundary(phys, size))
*dma_handle = dev_addr;
else {
if (xen_create_contiguous_region(phys, order,
fls64(dma_mask), dma_handle) != 0) {
xen_free_coherent_pages(hwdev, size, ret, (dma_addr_t)phys, attrs);
return NULL;
}
}
memset(ret, 0, size);
return ret;
}
static void
xen_swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr,
dma_addr_t dev_addr, unsigned long attrs)
{
int order = get_order(size);
phys_addr_t phys;
u64 dma_mask = DMA_BIT_MASK(32);
if (hwdev && hwdev->coherent_dma_mask)
dma_mask = hwdev->coherent_dma_mask;
/* do not use virt_to_phys because on ARM it doesn't return you the
* physical address */
phys = xen_bus_to_phys(dev_addr);
/* Convert the size to actually allocated. */
size = 1UL << (order + XEN_PAGE_SHIFT);
if (((dev_addr + size - 1 <= dma_mask)) ||
range_straddles_page_boundary(phys, size))
xen_destroy_contiguous_region(phys, order);
xen_free_coherent_pages(hwdev, size, vaddr, (dma_addr_t)phys, attrs);
}
/*
* 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.
*/
static dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page,
unsigned long offset, size_t size,
enum dma_data_direction dir,
unsigned long attrs)
{
phys_addr_t map, phys = page_to_phys(page) + offset;
dma_addr_t dev_addr = xen_phys_to_bus(phys);
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) &&
!xen_arch_need_swiotlb(dev, phys, dev_addr) &&
(swiotlb_force != SWIOTLB_FORCE)) {
/* we are not interested in the dma_addr returned by
* xen_dma_map_page, only in the potential cache flushes executed
* by the function. */
xen_dma_map_page(dev, page, dev_addr, offset, size, dir, attrs);
return dev_addr;
}
/*
* Oh well, have to allocate and map a bounce buffer.
*/
trace_swiotlb_bounced(dev, dev_addr, size, swiotlb_force);
map = swiotlb_tbl_map_single(dev, start_dma_addr, phys, size, dir,
attrs);
if (map == DMA_MAPPING_ERROR)
return DMA_MAPPING_ERROR;
dev_addr = xen_phys_to_bus(map);
xen_dma_map_page(dev, pfn_to_page(map >> PAGE_SHIFT),
dev_addr, map & ~PAGE_MASK, size, dir, attrs);
/*
* Ensure that the address returned is DMA'ble
*/
if (dma_capable(dev, dev_addr, size))
return dev_addr;
attrs |= DMA_ATTR_SKIP_CPU_SYNC;
swiotlb_tbl_unmap_single(dev, map, size, dir, attrs);
return DMA_MAPPING_ERROR;
}
/*
* 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,
unsigned long attrs)
{
phys_addr_t paddr = xen_bus_to_phys(dev_addr);
BUG_ON(dir == DMA_NONE);
xen_dma_unmap_page(hwdev, dev_addr, size, dir, attrs);
/* NOTE: We use dev_addr here, not paddr! */
if (is_xen_swiotlb_buffer(dev_addr))
swiotlb_tbl_unmap_single(hwdev, paddr, size, dir, attrs);
}
static void xen_swiotlb_unmap_page(struct device *hwdev, dma_addr_t dev_addr,
size_t size, enum dma_data_direction dir,
unsigned long attrs)
{
xen_unmap_single(hwdev, dev_addr, size, dir, attrs);
}
/*
* 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);
if (target == SYNC_FOR_CPU)
xen_dma_sync_single_for_cpu(hwdev, dev_addr, size, dir);
/* NOTE: We use dev_addr here, not paddr! */
if (is_xen_swiotlb_buffer(dev_addr))
swiotlb_tbl_sync_single(hwdev, paddr, size, dir, target);
if (target == SYNC_FOR_DEVICE)
xen_dma_sync_single_for_device(hwdev, dev_addr, size, dir);
}
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);
}
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);
}
/*
* Unmap a set of streaming mode DMA translations. Again, cpu read rules
* concerning calls here are the same as for swiotlb_unmap_page() above.
*/
static void
xen_swiotlb_unmap_sg_attrs(struct device *hwdev, struct scatterlist *sgl,
int nelems, enum dma_data_direction dir,
unsigned long 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_len(sg), dir, attrs);
}
/*
* 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.
*/
static int
xen_swiotlb_map_sg_attrs(struct device *hwdev, struct scatterlist *sgl,
int nelems, enum dma_data_direction dir,
unsigned long 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 == SWIOTLB_FORCE ||
xen_arch_need_swiotlb(hwdev, paddr, dev_addr) ||
!dma_capable(hwdev, dev_addr, sg->length) ||
range_straddles_page_boundary(paddr, sg->length)) {
phys_addr_t map = swiotlb_tbl_map_single(hwdev,
start_dma_addr,
sg_phys(sg),
sg->length,
dir, attrs);
if (map == DMA_MAPPING_ERROR) {
dev_warn(hwdev, "swiotlb buffer is full\n");
/* Don't panic here, we expect map_sg users
to do proper error handling. */
attrs |= DMA_ATTR_SKIP_CPU_SYNC;
xen_swiotlb_unmap_sg_attrs(hwdev, sgl, i, dir,
attrs);
sg_dma_len(sgl) = 0;
return 0;
}
dev_addr = xen_phys_to_bus(map);
xen_dma_map_page(hwdev, pfn_to_page(map >> PAGE_SHIFT),
dev_addr,
map & ~PAGE_MASK,
sg->length,
dir,
attrs);
sg->dma_address = dev_addr;
} else {
/* we are not interested in the dma_addr returned by
* xen_dma_map_page, only in the potential cache flushes executed
* by the function. */
xen_dma_map_page(hwdev, pfn_to_page(paddr >> PAGE_SHIFT),
dev_addr,
paddr & ~PAGE_MASK,
sg->length,
dir,
attrs);
sg->dma_address = dev_addr;
}
sg_dma_len(sg) = sg->length;
}
return nelems;
}
/*
* 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_len(sg), dir, target);
}
static 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);
}
static 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);
}
/*
* 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.
*/
static int
xen_swiotlb_dma_supported(struct device *hwdev, u64 mask)
{
return xen_virt_to_bus(xen_io_tlb_end - 1) <= mask;
}
/*
* Create userspace mapping for the DMA-coherent memory.
* This function should be called with the pages from the current domain only,
* passing pages mapped from other domains would lead to memory corruption.
*/
static int
xen_swiotlb_dma_mmap(struct device *dev, struct vm_area_struct *vma,
void *cpu_addr, dma_addr_t dma_addr, size_t size,
unsigned long attrs)
{
#ifdef CONFIG_ARM
if (xen_get_dma_ops(dev)->mmap)
return xen_get_dma_ops(dev)->mmap(dev, vma, cpu_addr,
dma_addr, size, attrs);
#endif
return dma_common_mmap(dev, vma, cpu_addr, dma_addr, size, attrs);
}
/*
* This function should be called with the pages from the current domain only,
* passing pages mapped from other domains would lead to memory corruption.
*/
static int
xen_swiotlb_get_sgtable(struct device *dev, struct sg_table *sgt,
void *cpu_addr, dma_addr_t handle, size_t size,
unsigned long attrs)
{
#ifdef CONFIG_ARM
if (xen_get_dma_ops(dev)->get_sgtable) {
#if 0
/*
* This check verifies that the page belongs to the current domain and
* is not one mapped from another domain.
* This check is for debug only, and should not go to production build
*/
unsigned long bfn = PHYS_PFN(dma_to_phys(dev, handle));
BUG_ON (!page_is_ram(bfn));
#endif
return xen_get_dma_ops(dev)->get_sgtable(dev, sgt, cpu_addr,
handle, size, attrs);
}
#endif
return dma_common_get_sgtable(dev, sgt, cpu_addr, handle, size, attrs);
}
const struct dma_map_ops xen_swiotlb_dma_ops = {
.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,
.mmap = xen_swiotlb_dma_mmap,
.get_sgtable = xen_swiotlb_get_sgtable,
};
