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[PATCH RFC v1 5/6] xen-swiotlb: convert variables to arrays



This patch converts several xen-swiotlb related variables to arrays, in
order to maintain stat/status for different swiotlb buffers. Here are
variables involved:

- xen_io_tlb_start and xen_io_tlb_end
- xen_io_tlb_nslabs
- MAX_DMA_BITS

There is no functional change and this is to prepare to enable 64-bit
xen-swiotlb.

Cc: Joe Jin <joe.jin@xxxxxxxxxx>
Signed-off-by: Dongli Zhang <dongli.zhang@xxxxxxxxxx>
---
 drivers/xen/swiotlb-xen.c | 75 +++++++++++++++++++++------------------
 1 file changed, 40 insertions(+), 35 deletions(-)

diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 662638093542..e18cae693cdc 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -39,15 +39,17 @@
 #include <asm/xen/page-coherent.h>
 
 #include <trace/events/swiotlb.h>
-#define MAX_DMA_BITS 32
 /*
  * 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;
+static char *xen_io_tlb_start[SWIOTLB_MAX], *xen_io_tlb_end[SWIOTLB_MAX];
+static unsigned long xen_io_tlb_nslabs[SWIOTLB_MAX];
+
+static int max_dma_bits[] = {32, 64};
+
 /*
  * Quick lookup value of the bus address of the IOTLB.
  */
@@ -112,8 +114,8 @@ static int is_xen_swiotlb_buffer(struct device *dev, 
dma_addr_t dma_addr)
         * 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 paddr >= virt_to_phys(xen_io_tlb_start[SWIOTLB_LO]) &&
+                      paddr < virt_to_phys(xen_io_tlb_end[SWIOTLB_LO]);
        }
        return 0;
 }
@@ -137,7 +139,7 @@ xen_swiotlb_fixup(void *buf, size_t size, unsigned long 
nslabs)
                                p + (i << IO_TLB_SHIFT),
                                get_order(slabs << IO_TLB_SHIFT),
                                dma_bits, &dma_handle);
-               } while (rc && dma_bits++ < MAX_DMA_BITS);
+               } while (rc && dma_bits++ < max_dma_bits[SWIOTLB_LO]);
                if (rc)
                        return rc;
 
@@ -148,12 +150,13 @@ xen_swiotlb_fixup(void *buf, size_t size, unsigned long 
nslabs)
 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);
+               xen_io_tlb_nslabs[SWIOTLB_LO] = (64 * 1024 * 1024 >> 
IO_TLB_SHIFT);
+               xen_io_tlb_nslabs[SWIOTLB_LO] = 
ALIGN(xen_io_tlb_nslabs[SWIOTLB_LO],
+                                                     IO_TLB_SEGSIZE);
        } else
-               xen_io_tlb_nslabs = nr_tbl;
+               xen_io_tlb_nslabs[SWIOTLB_LO] = nr_tbl;
 
-       return xen_io_tlb_nslabs << IO_TLB_SHIFT;
+       return xen_io_tlb_nslabs[SWIOTLB_LO] << IO_TLB_SHIFT;
 }
 
 enum xen_swiotlb_err {
@@ -184,16 +187,16 @@ int __ref xen_swiotlb_init(int verbose, bool early)
        enum xen_swiotlb_err m_ret = XEN_SWIOTLB_UNKNOWN;
        unsigned int repeat = 3;
 
-       xen_io_tlb_nslabs = swiotlb_nr_tbl(SWIOTLB_LO);
+       xen_io_tlb_nslabs[SWIOTLB_LO] = swiotlb_nr_tbl(SWIOTLB_LO);
 retry:
-       bytes = xen_set_nslabs(xen_io_tlb_nslabs);
-       order = get_order(xen_io_tlb_nslabs << IO_TLB_SHIFT);
+       bytes = xen_set_nslabs(xen_io_tlb_nslabs[SWIOTLB_LO]);
+       order = get_order(xen_io_tlb_nslabs[SWIOTLB_LO] << IO_TLB_SHIFT);
 
        /*
         * IO TLB memory already allocated. Just use it.
         */
        if (io_tlb_start[SWIOTLB_LO] != 0) {
-               xen_io_tlb_start = phys_to_virt(io_tlb_start[SWIOTLB_LO]);
+               xen_io_tlb_start[SWIOTLB_LO] = 
phys_to_virt(io_tlb_start[SWIOTLB_LO]);
                goto end;
        }
 
@@ -201,76 +204,78 @@ int __ref xen_swiotlb_init(int verbose, bool early)
         * Get IO TLB memory from any location.
         */
        if (early) {
-               xen_io_tlb_start = memblock_alloc(PAGE_ALIGN(bytes),
+               xen_io_tlb_start[SWIOTLB_LO] = memblock_alloc(PAGE_ALIGN(bytes),
                                                  PAGE_SIZE);
-               if (!xen_io_tlb_start)
+               if (!xen_io_tlb_start[SWIOTLB_LO])
                        panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
                              __func__, 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)
+                       xen_io_tlb_start[SWIOTLB_LO] = (void 
*)xen_get_swiotlb_free_pages(order);
+                       if (xen_io_tlb_start[SWIOTLB_LO])
                                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;
+                       xen_io_tlb_nslabs[SWIOTLB_LO] = SLABS_PER_PAGE << order;
+                       bytes = xen_io_tlb_nslabs[SWIOTLB_LO] << IO_TLB_SHIFT;
                }
        }
-       if (!xen_io_tlb_start) {
+       if (!xen_io_tlb_start[SWIOTLB_LO]) {
                m_ret = XEN_SWIOTLB_ENOMEM;
                goto error;
        }
        /*
         * And replace that memory with pages under 4GB.
         */
-       rc = xen_swiotlb_fixup(xen_io_tlb_start,
+       rc = xen_swiotlb_fixup(xen_io_tlb_start[SWIOTLB_LO],
                               bytes,
-                              xen_io_tlb_nslabs);
+                              xen_io_tlb_nslabs[SWIOTLB_LO]);
        if (rc) {
                if (early)
-                       memblock_free(__pa(xen_io_tlb_start),
+                       memblock_free(__pa(xen_io_tlb_start[SWIOTLB_LO]),
                                      PAGE_ALIGN(bytes));
                else {
-                       free_pages((unsigned long)xen_io_tlb_start, order);
-                       xen_io_tlb_start = NULL;
+                       free_pages((unsigned long)xen_io_tlb_start[SWIOTLB_LO], 
order);
+                       xen_io_tlb_start[SWIOTLB_LO] = NULL;
                }
                m_ret = XEN_SWIOTLB_EFIXUP;
                goto error;
        }
        if (early) {
-               if (swiotlb_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs,
+               if (swiotlb_init_with_tbl(xen_io_tlb_start[SWIOTLB_LO],
+                                         xen_io_tlb_nslabs[SWIOTLB_LO],
                                          SWIOTLB_LO, verbose))
                        panic("Cannot allocate SWIOTLB buffer");
                rc = 0;
        } else
-               rc = swiotlb_late_init_with_tbl(xen_io_tlb_start,
-                                               xen_io_tlb_nslabs, SWIOTLB_LO);
+               rc = swiotlb_late_init_with_tbl(xen_io_tlb_start[SWIOTLB_LO],
+                                               xen_io_tlb_nslabs[SWIOTLB_LO],
+                                               SWIOTLB_LO);
 
 end:
-       xen_io_tlb_end = xen_io_tlb_start + bytes;
+       xen_io_tlb_end[SWIOTLB_LO] = xen_io_tlb_start[SWIOTLB_LO] + bytes;
        if (!rc)
                swiotlb_set_max_segment(PAGE_SIZE, SWIOTLB_LO);
 
        return rc;
 error:
        if (repeat--) {
-               xen_io_tlb_nslabs = max(1024UL, /* Min is 2MB */
-                                       (xen_io_tlb_nslabs >> 1));
+               xen_io_tlb_nslabs[SWIOTLB_LO] = max(1024UL, /* Min is 2MB */
+                                       (xen_io_tlb_nslabs[SWIOTLB_LO] >> 1));
                pr_info("Lowering to %luMB\n",
-                       (xen_io_tlb_nslabs << IO_TLB_SHIFT) >> 20);
+                       (xen_io_tlb_nslabs[SWIOTLB_LO] << 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);
+               free_pages((unsigned long)xen_io_tlb_start[SWIOTLB_LO], order);
        return rc;
 }
 
@@ -561,7 +566,7 @@ xen_swiotlb_sync_sg_for_device(struct device *dev, struct 
scatterlist *sgl,
 static int
 xen_swiotlb_dma_supported(struct device *hwdev, u64 mask)
 {
-       return xen_virt_to_bus(hwdev, xen_io_tlb_end - 1) <= mask;
+       return xen_virt_to_bus(hwdev, xen_io_tlb_end[SWIOTLB_LO] - 1) <= mask;
 }
 
 const struct dma_map_ops xen_swiotlb_dma_ops = {
-- 
2.17.1




 


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