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Tsirkin" To: Jason Wang Cc: Wang Rong , kvm@vger.kernel.org, virtualization@lists.linux.dev, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3] vhost/vdpa: Add MSI translation tables to iommu for software-managed MSI Message-ID: <20240329064114-mutt-send-email-mst@kernel.org> References: <20240320101912.28210-1-w_angrong@163.com> <20240321025920-mutt-send-email-mst@kernel.org> <20240329051117-mutt-send-email-mst@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Fri, Mar 29, 2024 at 06:39:33PM +0800, Jason Wang wrote: > On Fri, Mar 29, 2024 at 5:13 PM Michael S. Tsirkin wrote: > > > > On Wed, Mar 27, 2024 at 05:08:57PM +0800, Jason Wang wrote: > > > On Thu, Mar 21, 2024 at 3:00 PM Michael S. Tsirkin wrote: > > > > > > > > On Wed, Mar 20, 2024 at 06:19:12PM +0800, Wang Rong wrote: > > > > > From: Rong Wang > > > > > > > > > > Once enable iommu domain for one device, the MSI > > > > > translation tables have to be there for software-managed MSI. > > > > > Otherwise, platform with software-managed MSI without an > > > > > irq bypass function, can not get a correct memory write event > > > > > from pcie, will not get irqs. > > > > > The solution is to obtain the MSI phy base address from > > > > > iommu reserved region, and set it to iommu MSI cookie, > > > > > then translation tables will be created while request irq. > > > > > > > > > > Change log > > > > > ---------- > > > > > > > > > > v1->v2: > > > > > - add resv iotlb to avoid overlap mapping. > > > > > v2->v3: > > > > > - there is no need to export the iommu symbol anymore. > > > > > > > > > > Signed-off-by: Rong Wang > > > > > > > > There's in interest to keep extending vhost iotlb - > > > > we should just switch over to iommufd which supports > > > > this already. > > > > > > IOMMUFD is good but VFIO supports this before IOMMUFD. > > > > You mean VFIO migrated to IOMMUFD but of course they keep supporting > > their old UAPI? > > I meant VFIO support software managed MSI before IOMMUFD. And then they switched over and stopped adding new IOMMU related features. And so should vdpa? > > OK and point being? > > > > > This patch > > > makes vDPA run without a backporting of full IOMMUFD in the production > > > environment. I think it's worth. > > > > Where do we stop? saying no to features is the only tool maintainers > > have to make cleanups happen, otherwise people will just keep piling > > stuff up. > > I think we should not have more features than VFIO without IOMMUFD. > > Thanks > > > > > > If you worry about the extension, we can just use the vhost iotlb > > > existing facility to do this. > > > > > > Thanks > > > > > > > > > > > > --- > > > > > drivers/vhost/vdpa.c | 59 +++++++++++++++++++++++++++++++++++++++++--- > > > > > 1 file changed, 56 insertions(+), 3 deletions(-) > > > > > > > > > > diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c > > > > > index ba52d128aeb7..28b56b10372b 100644 > > > > > --- a/drivers/vhost/vdpa.c > > > > > +++ b/drivers/vhost/vdpa.c > > > > > @@ -49,6 +49,7 @@ struct vhost_vdpa { > > > > > struct completion completion; > > > > > struct vdpa_device *vdpa; > > > > > struct hlist_head as[VHOST_VDPA_IOTLB_BUCKETS]; > > > > > + struct vhost_iotlb resv_iotlb; > > > > > struct device dev; > > > > > struct cdev cdev; > > > > > atomic_t opened; > > > > > @@ -247,6 +248,7 @@ static int _compat_vdpa_reset(struct vhost_vdpa *v) > > > > > static int vhost_vdpa_reset(struct vhost_vdpa *v) > > > > > { > > > > > v->in_batch = 0; > > > > > + vhost_iotlb_reset(&v->resv_iotlb); > > > > > return _compat_vdpa_reset(v); > > > > > } > > > > > > > > > > @@ -1219,10 +1221,15 @@ static int vhost_vdpa_process_iotlb_update(struct vhost_vdpa *v, > > > > > msg->iova + msg->size - 1 > v->range.last) > > > > > return -EINVAL; > > > > > > > > > > + if (vhost_iotlb_itree_first(&v->resv_iotlb, msg->iova, > > > > > + msg->iova + msg->size - 1)) > > > > > + return -EINVAL; > > > > > + > > > > > if (vhost_iotlb_itree_first(iotlb, msg->iova, > > > > > msg->iova + msg->size - 1)) > > > > > return -EEXIST; > > > > > > > > > > + > > > > > if (vdpa->use_va) > > > > > return vhost_vdpa_va_map(v, iotlb, msg->iova, msg->size, > > > > > msg->uaddr, msg->perm); > > > > > @@ -1307,6 +1314,45 @@ static ssize_t vhost_vdpa_chr_write_iter(struct kiocb *iocb, > > > > > return vhost_chr_write_iter(dev, from); > > > > > } > > > > > > > > > > +static int vhost_vdpa_resv_iommu_region(struct iommu_domain *domain, struct device *dma_dev, > > > > > + struct vhost_iotlb *resv_iotlb) > > > > > +{ > > > > > + struct list_head dev_resv_regions; > > > > > + phys_addr_t resv_msi_base = 0; > > > > > + struct iommu_resv_region *region; > > > > > + int ret = 0; > > > > > + bool with_sw_msi = false; > > > > > + bool with_hw_msi = false; > > > > > + > > > > > + INIT_LIST_HEAD(&dev_resv_regions); > > > > > + iommu_get_resv_regions(dma_dev, &dev_resv_regions); > > > > > + > > > > > + list_for_each_entry(region, &dev_resv_regions, list) { > > > > > + ret = vhost_iotlb_add_range_ctx(resv_iotlb, region->start, > > > > > + region->start + region->length - 1, > > > > > + 0, 0, NULL); > > > > > + if (ret) { > > > > > + vhost_iotlb_reset(resv_iotlb); > > > > > + break; > > > > > + } > > > > > + > > > > > + if (region->type == IOMMU_RESV_MSI) > > > > > + with_hw_msi = true; > > > > > + > > > > > + if (region->type == IOMMU_RESV_SW_MSI) { > > > > > + resv_msi_base = region->start; > > > > > + with_sw_msi = true; > > > > > + } > > > > > + } > > > > > + > > > > > + if (!ret && !with_hw_msi && with_sw_msi) > > > > > + ret = iommu_get_msi_cookie(domain, resv_msi_base); > > > > > + > > > > > + iommu_put_resv_regions(dma_dev, &dev_resv_regions); > > > > > + > > > > > + return ret; > > > > > +} > > > > > + > > > > > static int vhost_vdpa_alloc_domain(struct vhost_vdpa *v) > > > > > { > > > > > struct vdpa_device *vdpa = v->vdpa; > > > > > @@ -1335,11 +1381,16 @@ static int vhost_vdpa_alloc_domain(struct vhost_vdpa *v) > > > > > > > > > > ret = iommu_attach_device(v->domain, dma_dev); > > > > > if (ret) > > > > > - goto err_attach; > > > > > + goto err_alloc_domain; > > > > > > > > > > - return 0; > > > > > + ret = vhost_vdpa_resv_iommu_region(v->domain, dma_dev, &v->resv_iotlb); > > > > > + if (ret) > > > > > + goto err_attach_device; > > > > > > > > > > -err_attach: > > > > > + return 0; > > > > > +err_attach_device: > > > > > + iommu_detach_device(v->domain, dma_dev); > > > > > +err_alloc_domain: > > > > > iommu_domain_free(v->domain); > > > > > v->domain = NULL; > > > > > return ret; > > > > > @@ -1595,6 +1646,8 @@ static int vhost_vdpa_probe(struct vdpa_device *vdpa) > > > > > goto err; > > > > > } > > > > > > > > > > + vhost_iotlb_init(&v->resv_iotlb, 0, 0); > > > > > + > > > > > r = dev_set_name(&v->dev, "vhost-vdpa-%u", minor); > > > > > if (r) > > > > > goto err; > > > > > -- > > > > > 2.27.0 > > > > > > > > > > >