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author | Stefano Stabellini <stefano.stabellini@eu.citrix.com> | 2014-11-21 11:08:39 +0000 |
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committer | David Vrabel <david.vrabel@citrix.com> | 2014-12-04 12:41:54 +0000 |
commit | da095a996090a412c3b6292c7a8680661dca157d (patch) | |
tree | 02247bce77b50867c227384ed023bab81ffe77c4 /arch/arm | |
parent | a4dba130891271084344c12537731542ec77cb85 (diff) | |
download | linux-stable-da095a996090a412c3b6292c7a8680661dca157d.tar.gz linux-stable-da095a996090a412c3b6292c7a8680661dca157d.tar.bz2 linux-stable-da095a996090a412c3b6292c7a8680661dca157d.zip |
xen/arm: introduce GNTTABOP_cache_flush
Introduce support for new hypercall GNTTABOP_cache_flush.
Use it to perform cache flashing on pages used for dma when necessary.
If GNTTABOP_cache_flush is supported by the hypervisor, we don't need to
bounce dma map operations that involve foreign grants and non-coherent
devices.
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Diffstat (limited to 'arch/arm')
-rw-r--r-- | arch/arm/xen/mm.c | 34 |
1 files changed, 32 insertions, 2 deletions
diff --git a/arch/arm/xen/mm.c b/arch/arm/xen/mm.c index 28ebf3ecee4e..351b24a979d4 100644 --- a/arch/arm/xen/mm.c +++ b/arch/arm/xen/mm.c @@ -12,6 +12,7 @@ #include <linux/swiotlb.h> #include <xen/xen.h> +#include <xen/interface/grant_table.h> #include <xen/interface/memory.h> #include <xen/swiotlb-xen.h> @@ -24,12 +25,14 @@ enum dma_cache_op { DMA_UNMAP, DMA_MAP, }; +static bool hypercall_cflush = false; /* functions called by SWIOTLB */ static void dma_cache_maint(dma_addr_t handle, unsigned long offset, size_t size, enum dma_data_direction dir, enum dma_cache_op op) { + struct gnttab_cache_flush cflush; unsigned long pfn; size_t left = size; @@ -39,7 +42,26 @@ static void dma_cache_maint(dma_addr_t handle, unsigned long offset, do { size_t len = left; - /* TODO: cache flush */ + /* buffers in highmem or foreign pages cannot cross page + * boundaries */ + if (len + offset > PAGE_SIZE) + len = PAGE_SIZE - offset; + + cflush.op = 0; + cflush.a.dev_bus_addr = pfn << PAGE_SHIFT; + cflush.offset = offset; + cflush.length = len; + + if (op == DMA_UNMAP && dir != DMA_TO_DEVICE) + cflush.op = GNTTAB_CACHE_INVAL; + if (op == DMA_MAP) { + if (dir == DMA_FROM_DEVICE) + cflush.op = GNTTAB_CACHE_INVAL; + else + cflush.op = GNTTAB_CACHE_CLEAN; + } + if (cflush.op) + HYPERVISOR_grant_table_op(GNTTABOP_cache_flush, &cflush, 1); offset = 0; pfn++; @@ -104,7 +126,7 @@ bool xen_arch_need_swiotlb(struct device *dev, unsigned long pfn, unsigned long mfn) { - return ((pfn != mfn) && !is_device_dma_coherent(dev)); + return (!hypercall_cflush && (pfn != mfn) && !is_device_dma_coherent(dev)); } int xen_create_contiguous_region(phys_addr_t pstart, unsigned int order, @@ -147,10 +169,18 @@ static struct dma_map_ops xen_swiotlb_dma_ops = { int __init xen_mm_init(void) { + struct gnttab_cache_flush cflush; if (!xen_initial_domain()) return 0; xen_swiotlb_init(1, false); xen_dma_ops = &xen_swiotlb_dma_ops; + + cflush.op = 0; + cflush.a.dev_bus_addr = 0; + cflush.offset = 0; + cflush.length = 0; + if (HYPERVISOR_grant_table_op(GNTTABOP_cache_flush, &cflush, 1) != -ENOSYS) + hypercall_cflush = true; return 0; } arch_initcall(xen_mm_init); |