Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753564AbaJCPFU (ORCPT ); Fri, 3 Oct 2014 11:05:20 -0400 Received: from smtp02.citrix.com ([66.165.176.63]:25199 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751773AbaJCPFR (ORCPT ); Fri, 3 Oct 2014 11:05:17 -0400 X-IronPort-AV: E=Sophos;i="5.04,647,1406592000"; d="scan'208";a="178984361" Message-ID: <542EBB2A.6030104@citrix.com> Date: Fri, 3 Oct 2014 16:05:14 +0100 From: David Vrabel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Icedove/24.5.0 MIME-Version: 1.0 To: Stefano Stabellini , CC: , , , Subject: Re: [PATCH v2 2/2] xen/arm: introduce GNTTABOP_cache_flush References: <1412348006-27884-2-git-send-email-stefano.stabellini@eu.citrix.com> In-Reply-To: <1412348006-27884-2-git-send-email-stefano.stabellini@eu.citrix.com> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit X-DLP: MIA2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/10/14 15:53, Stefano Stabellini wrote: > Introduce support for new hypercall GNTTABOP_cache_flush. > Use it to perform cache flashing on pages used for dma when necessary. [..] > /* functions called by SWIOTLB */ > @@ -22,16 +25,31 @@ static void dma_cache_maint(dma_addr_t handle, unsigned long offset, > size_t len = left; > void *vaddr; > > + 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.size = len; > + > + if (op == dmac_unmap_area && dir != DMA_TO_DEVICE) > + cflush.op = GNTTAB_CACHE_INVAL; > + if (op == dmac_map_area) { > + cflush.op = GNTTAB_CACHE_CLEAN; > + if (dir == DMA_FROM_DEVICE) > + cflush.op |= GNTTAB_CACHE_INVAL; > + } Are all these cache operations needed? You do a clean on map regardless of the direction and INVAL on map seems unnecessary. I would have thought it would be: map && (TO_DEVICE || BOTH) op = CLEAN unmap && (FROM_DEVICE || BOTH) op = INVAL > --- a/include/xen/interface/grant_table.h > +++ b/include/xen/interface/grant_table.h > @@ -479,6 +479,24 @@ 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; > + uint32_t offset; /* offset from start of grant */ > + uint32_t size; /* size within the grant */ > +#define GNTTAB_CACHE_CLEAN (1<<0) > +#define GNTTAB_CACHE_INVAL (1<<1) > + 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. */ If the ARM bits are correct, have a Reviewed-by: David Vrabel for the common header. David -- 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/