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Thu, 02 Apr 2020 15:20:31 -0400 X-MC-Unique: l10McgFLN6-PWLYQYVF4GA-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 27D0818B641A; Thu, 2 Apr 2020 19:20:20 +0000 (UTC) Received: from w520.home (ovpn-112-162.phx2.redhat.com [10.3.112.162]) by smtp.corp.redhat.com (Postfix) with ESMTP id D507C5D9C9; Thu, 2 Apr 2020 19:20:12 +0000 (UTC) Date: Thu, 2 Apr 2020 13:20:12 -0600 From: Alex Williamson To: "Liu, Yi L" Subject: Re: [PATCH v1 5/8] vfio/type1: Report 1st-level/stage-1 format to userspace Message-ID: <20200402132012.390a7b54@w520.home> In-Reply-To: <1584880325-10561-6-git-send-email-yi.l.liu@intel.com> References: <1584880325-10561-1-git-send-email-yi.l.liu@intel.com> <1584880325-10561-6-git-send-email-yi.l.liu@intel.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Cc: jean-philippe@linaro.org, kevin.tian@intel.com, ashok.raj@intel.com, kvm@vger.kernel.org, jun.j.tian@intel.com, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, yi.y.sun@intel.com, hao.wu@intel.com X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On Sun, 22 Mar 2020 05:32:02 -0700 "Liu, Yi L" wrote: > From: Liu Yi L > > VFIO exposes IOMMU nesting translation (a.k.a dual stage translation) > capability to userspace. Thus applications like QEMU could support > vIOMMU with hardware's nesting translation capability for pass-through > devices. Before setting up nesting translation for pass-through devices, > QEMU and other applications need to learn the supported 1st-lvl/stage-1 > translation structure format like page table format. > > Take vSVA (virtual Shared Virtual Addressing) as an example, to support > vSVA for pass-through devices, QEMU setup nesting translation for pass- > through devices. The guest page table are configured to host as 1st-lvl/ > stage-1 page table. Therefore, guest format should be compatible with > host side. > > This patch reports the supported 1st-lvl/stage-1 page table format on the > current platform to userspace. QEMU and other alike applications should > use this format info when trying to setup IOMMU nesting translation on > host IOMMU. > > Cc: Kevin Tian > CC: Jacob Pan > Cc: Alex Williamson > Cc: Eric Auger > Cc: Jean-Philippe Brucker > Signed-off-by: Liu Yi L > --- > drivers/vfio/vfio_iommu_type1.c | 56 +++++++++++++++++++++++++++++++++++++++++ > include/uapi/linux/vfio.h | 1 + > 2 files changed, 57 insertions(+) > > diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c > index 9aa2a67..82a9e0b 100644 > --- a/drivers/vfio/vfio_iommu_type1.c > +++ b/drivers/vfio/vfio_iommu_type1.c > @@ -2234,11 +2234,66 @@ static int vfio_iommu_type1_pasid_free(struct vfio_iommu *iommu, > return ret; > } > > +static int vfio_iommu_get_stage1_format(struct vfio_iommu *iommu, > + u32 *stage1_format) > +{ > + struct vfio_domain *domain; > + u32 format = 0, tmp_format = 0; > + int ret; > + > + mutex_lock(&iommu->lock); > + if (list_empty(&iommu->domain_list)) { > + mutex_unlock(&iommu->lock); > + return -EINVAL; > + } > + > + list_for_each_entry(domain, &iommu->domain_list, next) { > + if (iommu_domain_get_attr(domain->domain, > + DOMAIN_ATTR_PASID_FORMAT, &format)) { > + ret = -EINVAL; > + format = 0; > + goto out_unlock; > + } > + /* > + * format is always non-zero (the first format is > + * IOMMU_PASID_FORMAT_INTEL_VTD which is 1). For > + * the reason of potential different backed IOMMU > + * formats, here we expect to have identical formats > + * in the domain list, no mixed formats support. > + * return -EINVAL to fail the attempt of setup > + * VFIO_TYPE1_NESTING_IOMMU if non-identical formats > + * are detected. > + */ > + if (tmp_format && tmp_format != format) { > + ret = -EINVAL; > + format = 0; > + goto out_unlock; > + } > + > + tmp_format = format; > + } > + ret = 0; > + > +out_unlock: > + if (format) > + *stage1_format = format; > + mutex_unlock(&iommu->lock); > + return ret; > +} > + > static int vfio_iommu_info_add_nesting_cap(struct vfio_iommu *iommu, > struct vfio_info_cap *caps) > { > struct vfio_info_cap_header *header; > struct vfio_iommu_type1_info_cap_nesting *nesting_cap; > + u32 formats = 0; > + int ret; > + > + ret = vfio_iommu_get_stage1_format(iommu, &formats); > + if (ret) { > + pr_warn("Failed to get stage-1 format\n"); > + return ret; Looks like this generates a warning and causes the iommu_get_info ioctl to fail if the hardware doesn't support the pasid format attribute, or the domain list is empty. This breaks users on existing hardware. > + } > > header = vfio_info_cap_add(caps, sizeof(*nesting_cap), > VFIO_IOMMU_TYPE1_INFO_CAP_NESTING, 1); > @@ -2254,6 +2309,7 @@ static int vfio_iommu_info_add_nesting_cap(struct vfio_iommu *iommu, > /* nesting iommu type supports PASID requests (alloc/free) */ > nesting_cap->nesting_capabilities |= VFIO_IOMMU_PASID_REQS; > } > + nesting_cap->stage1_formats = formats; > > return 0; > } > diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h > index ed9881d..ebeaf3e 100644 > --- a/include/uapi/linux/vfio.h > +++ b/include/uapi/linux/vfio.h > @@ -763,6 +763,7 @@ struct vfio_iommu_type1_info_cap_nesting { > struct vfio_info_cap_header header; > #define VFIO_IOMMU_PASID_REQS (1 << 0) > __u32 nesting_capabilities; > + __u32 stage1_formats; > }; > > #define VFIO_IOMMU_GET_INFO _IO(VFIO_TYPE, VFIO_BASE + 12) _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu