[PATCH v2 RFC 7/8] swiotlb-xen: support autotranslate guests
Stefano Stabellini
stefano.stabellini at eu.citrix.com
Wed Jul 31 15:54:11 EDT 2013
Support autotranslate guests in swiotlb-xen by keeping track of the
phys-to-bus and bus-to-phys mappings of the swiotlb buffer
(xen_io_tlb_start-xen_io_tlb_end).
Use a simple direct access on a pre-allocated array for phys-to-bus
queries. Use a red-black tree for bus-to-phys queries.
Signed-off-by: Stefano Stabellini <stefano.stabellini at eu.citrix.com>
CC: david.vrabel at citrix.com
---
drivers/xen/swiotlb-xen.c | 127 +++++++++++++++++++++++++++++++++++++++------
1 files changed, 111 insertions(+), 16 deletions(-)
diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 353f013..3fadb6b 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -38,32 +38,116 @@
#include <linux/bootmem.h>
#include <linux/dma-mapping.h>
#include <linux/export.h>
+#include <linux/slab.h>
+#include <linux/spinlock_types.h>
+#include <linux/rbtree.h>
#include <xen/swiotlb-xen.h>
#include <xen/page.h>
#include <xen/xen-ops.h>
#include <xen/hvc-console.h>
+#include <xen/features.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.
*/
+#define NR_DMA_SEGS ((xen_io_tlb_nslabs + IO_TLB_SEGSIZE - 1) / IO_TLB_SEGSIZE)
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;
+struct xen_dma{
+ dma_addr_t dma_addr;
+ phys_addr_t phys_addr;
+ size_t size;
+ struct rb_node rbnode;
+};
+
+static struct xen_dma *xen_dma_seg;
+static struct rb_root bus_to_phys = RB_ROOT;
+static DEFINE_SPINLOCK(xen_dma_lock);
+
+static void xen_dma_insert(struct xen_dma *entry)
+{
+ struct rb_node **link = &bus_to_phys.rb_node;
+ struct rb_node *parent = NULL;
+ struct xen_dma *e;
+
+ spin_lock(&xen_dma_lock);
+
+ while (*link) {
+ parent = *link;
+ e = rb_entry(parent, struct xen_dma, rbnode);
+
+ WARN_ON(entry->dma_addr == e->dma_addr);
+
+ if (entry->dma_addr < e->dma_addr)
+ link = &(*link)->rb_left;
+ else
+ link = &(*link)->rb_right;
+ }
+ rb_link_node(&entry->rbnode, parent, link);
+ rb_insert_color(&entry->rbnode, &bus_to_phys);
+
+ spin_unlock(&xen_dma_lock);
+}
+
+static struct xen_dma *xen_dma_retrieve(dma_addr_t dma_addr)
+{
+ struct rb_node *n = bus_to_phys.rb_node;
+ struct xen_dma *e;
+
+ spin_lock(&xen_dma_lock);
+
+ while (n) {
+ e = rb_entry(n, struct xen_dma, rbnode);
+ if (e->dma_addr <= dma_addr && e->dma_addr + e->size > dma_addr) {
+ spin_unlock(&xen_dma_lock);
+ return e;
+ }
+ if (dma_addr < e->dma_addr)
+ n = n->rb_left;
+ else
+ n = n->rb_right;
+ }
+
+ spin_unlock(&xen_dma_lock);
+ return NULL;
+}
static dma_addr_t xen_phys_to_bus(phys_addr_t paddr)
{
- return phys_to_machine(XPADDR(paddr)).maddr;
+ int nr_seg;
+ unsigned long offset;
+ char* vaddr;
+
+ if (!xen_feature(XENFEAT_auto_translated_physmap))
+ return phys_to_machine(XPADDR(paddr)).maddr;
+
+ vaddr = (char *) phys_to_virt(paddr);
+ if (vaddr >= xen_io_tlb_end || vaddr < xen_io_tlb_start)
+ return ~0;
+
+ offset = vaddr - xen_io_tlb_start;
+ nr_seg = offset / (IO_TLB_SEGSIZE << IO_TLB_SHIFT);
+
+ return xen_dma_seg[nr_seg].dma_addr + (paddr - xen_dma_seg[nr_seg].phys_addr);
}
static phys_addr_t xen_bus_to_phys(dma_addr_t baddr)
{
- return machine_to_phys(XMADDR(baddr)).paddr;
+ if (xen_feature(XENFEAT_auto_translated_physmap))
+ {
+ struct xen_dma *dma = xen_dma_retrieve(baddr);
+ if (dma == NULL)
+ return ~0;
+ else
+ return dma->phys_addr + (baddr - dma->dma_addr);
+ } else
+ return machine_to_phys(XMADDR(baddr)).paddr;
}
static dma_addr_t xen_virt_to_bus(void *address)
@@ -107,6 +191,9 @@ static int is_xen_swiotlb_buffer(dma_addr_t dma_addr)
unsigned long pfn = mfn_to_local_pfn(mfn);
phys_addr_t paddr;
+ if (xen_feature(XENFEAT_auto_translated_physmap))
+ return 1;
+
/* 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.
@@ -124,13 +211,12 @@ static int max_dma_bits = 32;
static int
xen_swiotlb_fixup(void *buf, size_t size, unsigned long nslabs)
{
- int i, rc;
+ int i, j, rc;
int dma_bits;
- dma_addr_t dma_handle;
dma_bits = get_order(IO_TLB_SEGSIZE << IO_TLB_SHIFT) + PAGE_SHIFT;
- i = 0;
+ i = j = 0;
do {
int slabs = min(nslabs - i, (unsigned long)IO_TLB_SEGSIZE);
@@ -138,12 +224,16 @@ xen_swiotlb_fixup(void *buf, size_t size, unsigned long nslabs)
rc = xen_create_contiguous_region(
(unsigned long)buf + (i << IO_TLB_SHIFT),
get_order(slabs << IO_TLB_SHIFT),
- dma_bits, &dma_handle);
+ dma_bits, &xen_dma_seg[j].dma_addr);
} while (rc && dma_bits++ < max_dma_bits);
if (rc)
return rc;
+ xen_dma_seg[j].phys_addr = virt_to_phys(buf + (i << IO_TLB_SHIFT));
+ xen_dma_seg[j].size = slabs << IO_TLB_SHIFT;
+ xen_dma_insert(&xen_dma_seg[j]);
i += slabs;
+ j++;
} while (i < nslabs);
return 0;
}
@@ -193,9 +283,10 @@ retry:
/*
* Get IO TLB memory from any location.
*/
- if (early)
+ if (early) {
xen_io_tlb_start = alloc_bootmem_pages(PAGE_ALIGN(bytes));
- else {
+ xen_dma_seg = alloc_bootmem(sizeof(struct xen_dma) * NR_DMA_SEGS);
+ } 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) {
@@ -210,6 +301,7 @@ retry:
xen_io_tlb_nslabs = SLABS_PER_PAGE << order;
bytes = xen_io_tlb_nslabs << IO_TLB_SHIFT;
}
+ xen_dma_seg = kzalloc(sizeof(struct xen_dma) * NR_DMA_SEGS, GFP_KERNEL);
}
if (!xen_io_tlb_start) {
m_ret = XEN_SWIOTLB_ENOMEM;
@@ -232,7 +324,6 @@ retry:
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))
@@ -290,7 +381,8 @@ xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
phys = virt_to_phys(ret);
dev_addr = xen_phys_to_bus(phys);
- if (((dev_addr + size - 1 <= dma_mask)) &&
+ if (!xen_feature(XENFEAT_auto_translated_physmap) &&
+ ((dev_addr + size - 1 <= dma_mask)) &&
!range_straddles_page_boundary(phys, size))
*dma_handle = dev_addr;
else {
@@ -321,8 +413,9 @@ xen_swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr,
phys = virt_to_phys(vaddr);
- if (((dev_addr + size - 1 > dma_mask)) ||
- range_straddles_page_boundary(phys, size))
+ if (xen_feature(XENFEAT_auto_translated_physmap) ||
+ (((dev_addr + size - 1 > dma_mask)) ||
+ range_straddles_page_boundary(phys, size)))
xen_destroy_contiguous_region((unsigned long)vaddr, order);
free_pages((unsigned long)vaddr, order);
@@ -351,14 +444,15 @@ dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page,
* we can safely return the device addr and not worry about bounce
* buffering it.
*/
- if (dma_capable(dev, dev_addr, size) &&
+ if (!xen_feature(XENFEAT_auto_translated_physmap) &&
+ 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);
+ map = swiotlb_tbl_map_single(dev, xen_dma_seg[0].dma_addr, phys, size, dir);
if (map == SWIOTLB_MAP_ERROR)
return DMA_ERROR_CODE;
@@ -494,10 +588,11 @@ xen_swiotlb_map_sg_attrs(struct device *hwdev, struct scatterlist *sgl,
dma_addr_t dev_addr = xen_phys_to_bus(paddr);
if (swiotlb_force ||
+ xen_feature(XENFEAT_auto_translated_physmap) ||
!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,
+ xen_dma_seg[0].dma_addr,
sg_phys(sg),
sg->length,
dir);
--
1.7.2.5
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