From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wei Wang2 Subject: Re: [PATCH 2/6] iommu: Introduce iommu_flush and iommu_flush_all. Date: Tue, 8 Nov 2011 11:39:15 +0100 Message-ID: <201111081139.15943.wei.wang2@amd.com> References: <1320678999-24995-1-git-send-email-jean.guyader@eu.citrix.com> <4EB8F549020000780005F87C@novprvoes0310.provo.novell.com> <20111108102515.GA7818@spongy.cam.xci-test.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20111108102515.GA7818@spongy.cam.xci-test.com> Content-Disposition: inline List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: xen-devel@lists.xensource.com Cc: "allen.m.kay@intel.com" , "Tim (Xen.org)" , Jean Guyader , Jan Beulich , Jean Guyader List-Id: xen-devel@lists.xenproject.org On Tuesday 08 November 2011 11:25:15 Jean Guyader wrote: > On 08/11 08:24, Jan Beulich wrote: > > >>> On 07.11.11 at 18:06, Jean Guyader > > >>> wrote: > > > > > > On 07/11 04:42, Jan Beulich wrote: > > >> >>> On 07.11.11 at 16:16, Jean Guyader > > >> >>> wrote: > > >> > > > >> > Signed-off-by: Jean Guyader > > >> > --- > > >> > xen/drivers/passthrough/iommu.c | 20 ++++++++++++++++++++ > > >> > xen/drivers/passthrough/vtd/iommu.c | 12 ++++++++++++ > > >> > xen/include/xen/iommu.h | 5 +++++ > > >> > 3 files changed, 37 insertions(+), 0 deletions(-) > > >> > > >> In iommu_iotlb_flush() you check whether the to-be-called function > > >> pointer is NULL, whereas in iommu_iotlb_flush_all() you don't. I > > >> actually think the second behavior is the correct one, but that > > >> implies that you need to also implement respective AMD IOMMU > > >> functions. > > > > > > Yes, It's an error on my part. I've updated the patch to check > > > for the present of iotlb_flush_all before I call it now. > > > > But as said, I don't think this is the right solution: How can it be > > correct on non-Intel hardware to have these functions simply do > > nothing? > > These functions are only here to counter balance the dont_flush_iotlb_flag. > If they don't acknowlage this flag doing nothing is the right thing to do. > > That said I can probably implement a naive version for the AMD iommu > that will use amd_iommu_flush_pages once or in a loop. There are some pending patches that enable ats / iotlb flush for amd iommu. Then, you might want to use functions: amd_iommu_flush_iotlb and amd_iommu_flush_all_iotlbs for this. Thanks, Wei > Obviously I will remove the check for the non existing callback if I do > that as it become mandatory. > > Jean > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xensource.com > http://lists.xensource.com/xen-devel