Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753345AbaJ0POA (ORCPT ); Mon, 27 Oct 2014 11:14:00 -0400 Received: from smtp.citrix.com ([66.165.176.89]:11947 "EHLO SMTP.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753143AbaJ0PNJ (ORCPT ); Mon, 27 Oct 2014 11:13:09 -0400 X-IronPort-AV: E=Sophos;i="5.04,796,1406592000"; d="scan'208";a="185211239" From: Stefano Stabellini To: CC: , , , , , , Stefano Stabellini Subject: [PATCH v7 8/8] xen/arm: introduce GNTTABOP_cache_flush Date: Mon, 27 Oct 2014 15:09:28 +0000 Message-ID: <1414422568-19103-8-git-send-email-stefano.stabellini@eu.citrix.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain X-DLP: MIA1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 Acked-by: Ian Campbell --- Changes in v5: - rename hypercall_flush to hypercall_cflush; - remove spurious change. Changes in v4: - add comment; - avoid bouncing dma map operations that involve foreign grants and non-coherent devices if GNTTABOP_cache_flush is provided by Xen. Changes in v3: - fix the cache maintenance op call to match what Linux does natively; - update the hypercall interface to match Xen. Changes in v2: - update the hypercall interface to match Xen; - call the interface on a single page at a time. --- arch/arm/xen/mm.c | 39 ++++++++++++++++++++++++++++++----- include/xen/interface/grant_table.h | 19 +++++++++++++++++ 2 files changed, 53 insertions(+), 5 deletions(-) diff --git a/arch/arm/xen/mm.c b/arch/arm/xen/mm.c index 28396aa..e20a57f 100644 --- a/arch/arm/xen/mm.c +++ b/arch/arm/xen/mm.c @@ -12,6 +12,7 @@ #include #include +#include #include #include @@ -20,6 +21,8 @@ #include #include +static bool hypercall_cflush = false; + #ifdef CONFIG_ARM64 static inline void dmac_map_area(const void *start, size_t size, int dir) @@ -60,17 +63,35 @@ static void dma_cache_maint(dma_addr_t handle, unsigned long offset, do { size_t len = left; void *vaddr; + + /* buffers in highmem or foreign pages cannot cross page + * boundaries */ + if (len + offset > PAGE_SIZE) + len = PAGE_SIZE - offset; if (!pfn_valid(pfn)) { - /* TODO: cache flush */ + struct gnttab_cache_flush cflush; + + cflush.op = 0; + cflush.a.dev_bus_addr = pfn << PAGE_SHIFT; + cflush.offset = offset; + cflush.length = len; + + if (op == dmac_unmap_area && dir != DMA_TO_DEVICE) + cflush.op = GNTTAB_CACHE_INVAL; + if (op == dmac_map_area) { + 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); } else { struct page *page = pfn_to_page(pfn); if (PageHighMem(page)) { - if (len + offset > PAGE_SIZE) - len = PAGE_SIZE - offset; - if (cache_is_vipt_nonaliasing()) { vaddr = kmap_atomic(page); op(vaddr + offset, len, dir); @@ -143,7 +164,7 @@ 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, @@ -186,10 +207,18 @@ 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 e40fae9..bcce564 100644 --- a/include/xen/interface/grant_table.h +++ b/include/xen/interface/grant_table.h @@ -479,6 +479,25 @@ 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. */ /* Map the grant entry for access by I/O devices. */ -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/