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Tue, 15 Sep 2020 19:05:23 +0000 (GMT) Received: from b03ledav004.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 5A0027805F; Tue, 15 Sep 2020 19:05:22 +0000 (GMT) Received: from oc4221205838.ibm.com (unknown [9.163.85.51]) by b03ledav004.gho.boulder.ibm.com (Postfix) with ESMTP; Tue, 15 Sep 2020 19:05:22 +0000 (GMT) From: Matthew Rosato To: alex.williamson@redhat.com, cohuck@redhat.com Cc: pmorel@linux.ibm.com, schnelle@linux.ibm.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3] vfio iommu: Add dma available capability Date: Tue, 15 Sep 2020 15:05:18 -0400 Message-Id: <1600196718-23238-2-git-send-email-mjrosato@linux.ibm.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1600196718-23238-1-git-send-email-mjrosato@linux.ibm.com> References: <1600196718-23238-1-git-send-email-mjrosato@linux.ibm.com> X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235,18.0.687 definitions=2020-09-15_12:2020-09-15,2020-09-15 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 impostorscore=0 malwarescore=0 suspectscore=0 phishscore=0 clxscore=1015 spamscore=0 bulkscore=0 adultscore=0 mlxlogscore=739 priorityscore=1501 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2009150147 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit 492855939bdb ("vfio/type1: Limit DMA mappings per container") added the ability to limit the number of memory backed DMA mappings. However on s390x, when lazy mapping is in use, we use a very large number of concurrent mappings. Let's provide the current allowable number of DMA mappings to userspace via the IOMMU info chain so that userspace can take appropriate mitigation. Signed-off-by: Matthew Rosato --- drivers/vfio/vfio_iommu_type1.c | 17 +++++++++++++++++ include/uapi/linux/vfio.h | 15 +++++++++++++++ 2 files changed, 32 insertions(+) diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c index 5fbf0c1..15e21db 100644 --- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -2609,6 +2609,20 @@ static int vfio_iommu_migration_build_caps(struct vfio_iommu *iommu, return vfio_info_add_capability(caps, &cap_mig.header, sizeof(cap_mig)); } +static int vfio_iommu_dma_avail_build_caps(struct vfio_iommu *iommu, + struct vfio_info_cap *caps) +{ + struct vfio_iommu_type1_info_dma_avail cap_dma_avail; + + cap_dma_avail.header.id = VFIO_IOMMU_TYPE1_INFO_DMA_AVAIL; + cap_dma_avail.header.version = 1; + + cap_dma_avail.avail = iommu->dma_avail; + + return vfio_info_add_capability(caps, &cap_dma_avail.header, + sizeof(cap_dma_avail)); +} + static int vfio_iommu_type1_get_info(struct vfio_iommu *iommu, unsigned long arg) { @@ -2642,6 +2656,9 @@ static int vfio_iommu_type1_get_info(struct vfio_iommu *iommu, ret = vfio_iommu_migration_build_caps(iommu, &caps); if (!ret) + ret = vfio_iommu_dma_avail_build_caps(iommu, &caps); + + if (!ret) ret = vfio_iommu_iova_build_caps(iommu, &caps); mutex_unlock(&iommu->lock); diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h index 9204705..3891e03 100644 --- a/include/uapi/linux/vfio.h +++ b/include/uapi/linux/vfio.h @@ -1039,6 +1039,21 @@ struct vfio_iommu_type1_info_cap_migration { __u64 max_dirty_bitmap_size; /* in bytes */ }; +/* + * The DMA available capability allows to report the current number of + * simultaneously outstanding DMA mappings that are allowed. + * + * The structure below defines version 1 of this capability. + * + * avail: specifies the current number of outstanding DMA mappings allowed. + */ +#define VFIO_IOMMU_TYPE1_INFO_DMA_AVAIL 3 + +struct vfio_iommu_type1_info_dma_avail { + struct vfio_info_cap_header header; + __u32 avail; +}; + #define VFIO_IOMMU_GET_INFO _IO(VFIO_TYPE, VFIO_BASE + 12) /** -- 1.8.3.1