path: root/arch
diff options
authorIan Campbell <ian.campbell@citrix.com>2014-01-20 11:30:41 +0000
committerStefano Stabellini <stefano.stabellini@eu.citrix.com>2014-01-30 12:54:20 +0000
commite17b2f114cba5420fb28fa4bfead57d406a16533 (patch)
tree0a30053f6a3cc7bcf835b4acb61aa7a0a2d3c19b /arch
parent8b271d57b57585a3e3e8cd7abc5f4d7710a0e62d (diff)
xen: swiotlb: handle sizeof(dma_addr_t) != sizeof(phys_addr_t)
The use of phys_to_machine and machine_to_phys in the phys<=>bus conversions causes us to lose the top bits of the DMA address if the size of a DMA address is not the same as the size of the phyiscal address. This can happen in practice on ARM where foreign pages can be above 4GB even though the local kernel does not have LPAE page tables enabled (which is totally reasonable if the guest does not itself have >4GB of RAM). In this case the kernel still maps the foreign pages at a phys addr below 4G (as it must) but the resulting DMA address (returned by the grant map operation) is much higher. This is analogous to a hardware device which has its view of RAM mapped up high for some reason. This patch makes I/O to foreign pages (specifically blkif) work on 32-bit ARM systems with more than 4GB of RAM. Signed-off-by: Ian Campbell <ian.campbell@citrix.com> Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Diffstat (limited to 'arch')
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index c1f1a7eee953..24307dc85d08 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1885,6 +1885,7 @@ config XEN
depends on !GENERIC_ATOMIC64
select ARM_PSCI
+ select ARCH_DMA_ADDR_T_64BIT
Say Y if you want to run Linux in a Virtual Machine on Xen on ARM.