From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754189AbdEJSmM (ORCPT ); Wed, 10 May 2017 14:42:12 -0400 Received: from mga05.intel.com ([192.55.52.43]:32085 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753732AbdEJSmK (ORCPT ); Wed, 10 May 2017 14:42:10 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.38,320,1491289200"; d="scan'208";a="1146293111" From: Ashok Raj To: Joerg Roedel , linux-kernel@vger.kernel.org Cc: CQ Tang , linux-pci@vger.kernel.org, Jean-Phillipe Brucker , iommu@lists.linux-foundation.org, Ashok Raj Subject: [PATCH 2/2] iommu/vt-d: Helper function to query if a pasid has any active users Date: Wed, 10 May 2017 11:39:03 -0700 Message-Id: <1494441543-8216-2-git-send-email-ashok.raj@intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1494441543-8216-1-git-send-email-ashok.raj@intel.com> References: <1494441543-8216-1-git-send-email-ashok.raj@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: CQ Tang A driver would need to know if there are any active references to a a PASID before cleaning up its resources. This function helps check if there are any active users of a PASID before it can perform any recovery on that device. To: Joerg Roedel To: linux-kernel@vger.kernel.org To: David Woodhouse Cc: Jean-Phillipe Brucker Cc: iommu@lists.linux-foundation.org Signed-off-by: CQ Tang Signed-off-by: Ashok Raj --- drivers/iommu/intel-svm.c | 30 ++++++++++++++++++++++++++++++ include/linux/intel-svm.h | 20 ++++++++++++++++++++ 2 files changed, 50 insertions(+) diff --git a/drivers/iommu/intel-svm.c b/drivers/iommu/intel-svm.c index 23c4276..f167c0d 100644 --- a/drivers/iommu/intel-svm.c +++ b/drivers/iommu/intel-svm.c @@ -489,6 +489,36 @@ int intel_svm_unbind_mm(struct device *dev, int pasid) } EXPORT_SYMBOL_GPL(intel_svm_unbind_mm); +int intel_svm_is_pasid_valid(struct device *dev, int pasid) +{ + struct intel_iommu *iommu; + struct intel_svm *svm; + int ret = -EINVAL; + + mutex_lock(&pasid_mutex); + iommu = intel_svm_device_to_iommu(dev); + if (!iommu || !iommu->pasid_table) + goto out; + + svm = idr_find(&iommu->pasid_idr, pasid); + if (!svm) + goto out; + + /* init_mm is used in this case */ + if (!svm->mm) + ret = 1; + else if (atomic_read(&svm->mm->mm_users) > 0) + ret = 1; + else + ret = 0; + + out: + mutex_unlock(&pasid_mutex); + + return ret; +} +EXPORT_SYMBOL_GPL(intel_svm_is_pasid_valid); + /* Page request queue descriptor */ struct page_req_dsc { u64 srr:1; diff --git a/include/linux/intel-svm.h b/include/linux/intel-svm.h index 3c25794..99bc5b3 100644 --- a/include/linux/intel-svm.h +++ b/include/linux/intel-svm.h @@ -102,6 +102,21 @@ extern int intel_svm_bind_mm(struct device *dev, int *pasid, int flags, */ extern int intel_svm_unbind_mm(struct device *dev, int pasid); +/** + * intel_svm_is_pasid_valid() - check if pasid is valid + * @dev: Device for which PASID was allocated + * @pasid: PASID value to be checked + * + * This function checks if the specified pasid is still valid. A + * valid pasid means the backing mm is still having a valid user. + * For kernel callers init_mm is always valid. for other mm, if mm->mm_users + * is non-zero, it is valid. + * + * returns -EINVAL if invalid pasid, 0 if pasid ref count is invalid + * 1 if pasid is valid. + */ +extern int intel_svm_is_pasid_valid(struct device *dev, int pasid); + #else /* CONFIG_INTEL_IOMMU_SVM */ static inline int intel_svm_bind_mm(struct device *dev, int *pasid, @@ -114,6 +129,11 @@ static inline int intel_svm_unbind_mm(struct device *dev, int pasid) { BUG(); } + +static int intel_svm_is_pasid_valid(struct device *dev, int pasid) +{ + return -EINVAL; +} #endif /* CONFIG_INTEL_IOMMU_SVM */ #define intel_svm_available(dev) (!intel_svm_bind_mm((dev), NULL, 0, NULL)) -- 2.7.4