From 63a741757d15320a25ebf5778f8651cce2ed0611 Mon Sep 17 00:00:00 2001 From: Konrad Rzeszutek Wilk Date: Thu, 15 Dec 2011 11:28:46 -0500 Subject: [PATCH] xen/swiotlb: Use page alignment for early buffer allocation. This fixes an odd bug found on a Dell PowerEdge 1850/0RC130 (BIOS A05 01/09/2006) where all of the modules doing pci_set_dma_mask would fail with: ata_piix 0000:00:1f.1: enabling device (0005 -> 0007) ata_piix 0000:00:1f.1: can't derive routing for PCI INT A ata_piix 0000:00:1f.1: BMDMA: failed to set dma mask, falling back to PIO The issue was the Xen-SWIOTLB was allocated such as that the end of buffer was stradling a page (and also above 4GB). The fix was spotted by Kalev Leonid which was to piggyback on git commit e79f86b2ef9c0a8c47225217c1018b7d3d90101c "swiotlb: Use page alignment for early buffer allocation" which: We could call free_bootmem_late() if swiotlb is not used, and it will shrink to page alignment. So alloc them with page alignment at first, to avoid lose two pages And doing that fixes the outstanding issue. CC: stable@kernel.org Suggested-by: "Kalev, Leonid" Reported-and-Tested-by: "Taylor, Neal E" Signed-off-by: Konrad Rzeszutek Wilk --- drivers/xen/swiotlb-xen.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c index 8e964b91c447..284798aaf8b1 100644 --- a/drivers/xen/swiotlb-xen.c +++ b/drivers/xen/swiotlb-xen.c @@ -166,7 +166,7 @@ void __init xen_swiotlb_init(int verbose) /* * Get IO TLB memory from any location. */ - xen_io_tlb_start = alloc_bootmem(bytes); + xen_io_tlb_start = alloc_bootmem_pages(PAGE_ALIGN(bytes)); if (!xen_io_tlb_start) { m = "Cannot allocate Xen-SWIOTLB buffer!\n"; goto error; @@ -179,7 +179,7 @@ void __init xen_swiotlb_init(int verbose) bytes, xen_io_tlb_nslabs); if (rc) { - free_bootmem(__pa(xen_io_tlb_start), bytes); + free_bootmem(__pa(xen_io_tlb_start), PAGE_ALIGN(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"\