From da095a996090a412c3b6292c7a8680661dca157d Mon Sep 17 00:00:00 2001 From: Stefano Stabellini Date: Fri, 21 Nov 2014 11:08:39 +0000 Subject: [PATCH] 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 Reviewed-by: Catalin Marinas Acked-by: Ian Campbell --- arch/arm/xen/mm.c | 34 +++++++++++++++++++++++++++-- include/xen/interface/grant_table.h | 19 ++++++++++++++++ 2 files changed, 51 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 #include +#include #include #include @@ -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); diff --git a/include/xen/interface/grant_table.h b/include/xen/interface/grant_table.h index e40fae9bf11a..bcce56439d64 100644 --- a/include/xen/interface/grant_table.h +++ b/include/xen/interface/grant_table.h @@ -478,6 +478,25 @@ struct gnttab_get_version { }; DEFINE_GUEST_HANDLE_STRUCT(gnttab_get_version); +/* + * Issue one or more cache maintenance operations on a portion of a + * page granted to the calling domain by a foreign domain. + */ +#define GNTTABOP_cache_flush 12 +struct gnttab_cache_flush { + union { + uint64_t dev_bus_addr; + grant_ref_t ref; + } a; + uint16_t offset; /* offset from start of grant */ + uint16_t length; /* size within the grant */ +#define GNTTAB_CACHE_CLEAN (1<<0) +#define GNTTAB_CACHE_INVAL (1<<1) +#define GNTTAB_CACHE_SOURCE_GREF (1<<31) + uint32_t op; +}; +DEFINE_GUEST_HANDLE_STRUCT(gnttab_cache_flush); + /* * Bitfield values for update_pin_status.flags. */