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Fri, 15 Jan 2021 18:01:47 +0000 (UTC) Received: from omen.home.shazbot.org (ovpn-112-255.phx2.redhat.com [10.3.112.255]) by smtp.corp.redhat.com (Postfix) with ESMTP id 90E4460BF3; Fri, 15 Jan 2021 18:01:45 +0000 (UTC) Date: Fri, 15 Jan 2021 11:01:44 -0700 From: Alex Williamson To: Keqian Zhu Cc: , , , , , Kirti Wankhede , Cornelia Huck , Will Deacon , Marc Zyngier , Catalin Marinas , Mark Rutland , James Morse , Robin Murphy , Joerg Roedel , "Daniel Lezcano" , Thomas Gleixner , Suzuki K Poulose , Julien Thierry , Andrew Morton , Alexios Zavras , , Subject: Re: [PATCH v2 1/2] vfio/iommu_type1: Populate full dirty when detach non-pinned group Message-ID: <20210115110144.61e3c843@omen.home.shazbot.org> In-Reply-To: <20210115092643.728-2-zhukeqian1@huawei.com> References: <20210115092643.728-1-zhukeqian1@huawei.com> <20210115092643.728-2-zhukeqian1@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Fri, 15 Jan 2021 17:26:42 +0800 Keqian Zhu wrote: > If a group with non-pinned-page dirty scope is detached with dirty > logging enabled, we should fully populate the dirty bitmaps at the > time it's removed since we don't know the extent of its previous DMA, > nor will the group be present to trigger the full bitmap when the user > retrieves the dirty bitmap. > > Fixes: d6a4c185660c ("vfio iommu: Implementation of ioctl for dirty pages tracking") > Suggested-by: Alex Williamson > Signed-off-by: Keqian Zhu > --- > drivers/vfio/vfio_iommu_type1.c | 18 +++++++++++++++++- > 1 file changed, 17 insertions(+), 1 deletion(-) > > diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c > index 0b4dedaa9128..4e82b9a3440f 100644 > --- a/drivers/vfio/vfio_iommu_type1.c > +++ b/drivers/vfio/vfio_iommu_type1.c > @@ -236,6 +236,19 @@ static void vfio_dma_populate_bitmap(struct vfio_dma *dma, size_t pgsize) > } > } > > +static void vfio_iommu_populate_bitmap_full(struct vfio_iommu *iommu) > +{ > + struct rb_node *n; > + unsigned long pgshift = __ffs(iommu->pgsize_bitmap); > + > + for (n = rb_first(&iommu->dma_list); n; n = rb_next(n)) { > + struct vfio_dma *dma = rb_entry(n, struct vfio_dma, node); > + > + if (dma->iommu_mapped) > + bitmap_set(dma->bitmap, 0, dma->size >> pgshift); > + } > +} > + > static int vfio_dma_bitmap_alloc_all(struct vfio_iommu *iommu, size_t pgsize) > { > struct rb_node *n; > @@ -2415,8 +2428,11 @@ static void vfio_iommu_type1_detach_group(void *iommu_data, > * Removal of a group without dirty tracking may allow the iommu scope > * to be promoted. > */ > - if (update_dirty_scope) > + if (update_dirty_scope) { > update_pinned_page_dirty_scope(iommu); > + if (iommu->dirty_page_tracking) > + vfio_iommu_populate_bitmap_full(iommu); > + } > mutex_unlock(&iommu->lock); > } > This doesn't do the right thing. This marks the bitmap dirty if: * The detached group dirty scope was not limited to pinned pages AND * Dirty tracking is enabled AND * The vfio_dma is *currently* (ie. after the detach) iommu_mapped We need to mark the bitmap dirty based on whether the vfio_dma *was* iommu_mapped by the group that is now detached. Thanks, Alex