We can fail seting up Xen-SWIOTLB if:
- The host does not have enough contiguous DMA32 memory available
(can happen on a machine that has fragmented memory from starting,
stopping many guests).
- Not enough low memory (almost never happens).
We retry allocating and exchanging the swath of contiguous memory
up to three times. Each time we decrease the amount we need - the
minimum being of 2MB.
If we completly fail, we will print the reason for failure on the Xen
console on top of doing it to earlyprintk=xen console.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
drivers/xen/swiotlb-xen.c | 35 +++++++++++++++++++++++++----------
1 files changed, 25 insertions(+), 10 deletions(-)
diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 6e8c15a..d45cbac 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -38,6 +38,7 @@
#include <xen/swiotlb-xen.h>
#include <xen/page.h>
#include <xen/xen-ops.h>
+#include <xen/hvc-console.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
@@ -146,8 +147,10 @@ xen_swiotlb_fixup(void *buf, size_t size, unsigned long
nslabs)
void __init xen_swiotlb_init(int verbose)
{
unsigned long bytes;
- int rc;
+ int rc = -ENOMEM;
unsigned long nr_tbl;
+ char *m = NULL;
+ unsigned int repeat = 3;
nr_tbl = swioltb_nr_tbl();
if (nr_tbl)
@@ -156,16 +159,17 @@ void __init xen_swiotlb_init(int verbose)
xen_io_tlb_nslabs = (64 * 1024 * 1024 >> IO_TLB_SHIFT);
xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs, IO_TLB_SEGSIZE);
}
-
+retry:
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");
-
+ if (!xen_io_tlb_start) {
+ m = "Cannot allocate Xen-SWIOTLB buffer!\n";
+ goto error;
+ }
xen_io_tlb_end = xen_io_tlb_start + bytes;
/*
* And replace that memory with pages under 4GB.
@@ -173,17 +177,28 @@ void __init xen_swiotlb_init(int verbose)
rc = xen_swiotlb_fixup(xen_io_tlb_start,
bytes,
xen_io_tlb_nslabs);
- if (rc)
+ if (rc) {
+ free_bootmem(__pa(xen_io_tlb_start), bytes);
+ m = "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!";
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);
+ if (repeat--) {
+ xen_io_tlb_nslabs = max(1024UL, /* Min is 2MB */
+ (xen_io_tlb_nslabs >> 1));
+ printk(KERN_INFO "Xen-SWIOTLB: Lowering to %luMB\n",
+ (xen_io_tlb_nslabs << IO_TLB_SHIFT) >> 20);
+ goto retry;
+ }
+ xen_raw_printk("%s (rc:%d)", rc, m);
+ panic("%s (rc:%d)", rc, m);
}
void *
--
1.7.4.1
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