From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39622) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cELVK-0003jv-Oo for qemu-devel@nongnu.org; Tue, 06 Dec 2016 14:34:19 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cELVH-0002I2-FP for qemu-devel@nongnu.org; Tue, 06 Dec 2016 14:34:18 -0500 Received: from mx1.redhat.com ([209.132.183.28]:39398) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cELVH-0002Hi-9K for qemu-devel@nongnu.org; Tue, 06 Dec 2016 14:34:15 -0500 Date: Tue, 6 Dec 2016 12:34:13 -0700 From: Alex Williamson Message-ID: <20161206123413.5bdeb1fb@t450s.home> In-Reply-To: <1481048814-29752-1-git-send-email-kwankhede@nvidia.com> References: <1481044410-23862-1-git-send-email-kwankhede@nvidia.com> <1481048814-29752-1-git-send-email-kwankhede@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v2 1/2] vfio iommu type1: Fix size argument to vfio_find_dma() during DMA UNMAP. List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kirti Wankhede Cc: pbonzini@redhat.com, kraxel@redhat.com, cjia@nvidia.com, qemu-devel@nongnu.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org On Tue, 6 Dec 2016 23:56:54 +0530 Kirti Wankhede wrote: > Passing zero for the size to vfio_find_dma() isn't compatible with > matching the start address of an existing vfio_dma. Doing so triggers a > corner case. In vfio_find_dma(), when the start address is equal to > dma->iova and size is 0, check for the end of search range makes it to > take wrong side of RB-tree. That fails the search even though the address > is present in mapped dma ranges. Due to this, in vfio_dma_do_unmap(), > while checking boundary conditions, size should be set to 1 for verifying > start address of unmap range. > vfio_find_dma() is also used to verify last address in unmap range with > size = 0, but in that case address to be searched is calculated with > size - 1 and so it works correctly. I think this last sentence should actually read "start + size - 1", or at least that makes it more understandable for me. I'll make that change and apply these. Thanks, Alex > Signed-off-by: Kirti Wankhede > Signed-off-by: Neo Jia > --- > drivers/vfio/vfio_iommu_type1.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c > index a28fbddb505c..8e9e94ccb2ff 100644 > --- a/drivers/vfio/vfio_iommu_type1.c > +++ b/drivers/vfio/vfio_iommu_type1.c > @@ -826,7 +826,7 @@ again: > * mappings within the range. > */ > if (iommu->v2) { > - dma = vfio_find_dma(iommu, unmap->iova, 0); > + dma = vfio_find_dma(iommu, unmap->iova, 1); > if (dma && dma->iova != unmap->iova) { > ret = -EINVAL; > goto unlock;