From patchwork Wed Feb 19 06:07:33 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jiang Liu X-Patchwork-Id: 3678271 Return-Path: X-Original-To: patchwork-dmaengine@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id A19FCBF13A for ; Wed, 19 Feb 2014 06:09:08 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 6D476200F0 for ; Wed, 19 Feb 2014 06:09:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1BAC5200D6 for ; Wed, 19 Feb 2014 06:09:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752580AbaBSGHu (ORCPT ); Wed, 19 Feb 2014 01:07:50 -0500 Received: from mga09.intel.com ([134.134.136.24]:18482 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752451AbaBSGHp (ORCPT ); Wed, 19 Feb 2014 01:07:45 -0500 Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga102.jf.intel.com with ESMTP; 18 Feb 2014 22:03:25 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.97,504,1389772800"; d="scan'208";a="485626705" Received: from gerry-dev.bj.intel.com ([10.238.158.74]) by orsmga002.jf.intel.com with ESMTP; 18 Feb 2014 22:07:41 -0800 From: Jiang Liu To: Joerg Roedel , David Woodhouse , Yinghai Lu , Bjorn Helgaas , Dan Williams , Vinod Koul , "Rafael J . Wysocki" Cc: Jiang Liu , Ashok Raj , Yijing Wang , Tony Luck , iommu@lists.linux-foundation.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, dmaengine@vger.kernel.org Subject: [Patch Part2 V2 13/17] iommu/vt-d: introduce a rwsem to protect global data structures Date: Wed, 19 Feb 2014 14:07:33 +0800 Message-Id: <1392790057-32434-14-git-send-email-jiang.liu@linux.intel.com> X-Mailer: git-send-email 1.7.10.4 In-Reply-To: <1392790057-32434-1-git-send-email-jiang.liu@linux.intel.com> References: <1392790057-32434-1-git-send-email-jiang.liu@linux.intel.com> Sender: dmaengine-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: dmaengine@vger.kernel.org X-Spam-Status: No, score=-4.6 required=5.0 tests=BAYES_00,KHOP_BIG_TO_CC, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Introduce a global rwsem dmar_global_lock, which will be used to protect DMAR related global data structures from DMAR/PCI/memory device hotplug operations in process context. DMA and interrupt remapping related data structures are read most, and only change when memory/PCI/DMAR hotplug event happens. So a global rwsem solution is adopted for balance between simplicity and performance. For interrupt remapping driver, function intel_irq_remapping_supported(), dmar_table_init(), intel_enable_irq_remapping(), disable_irq_remapping(), reenable_irq_remapping() and enable_drhd_fault_handling() etc are called during booting, suspending and resuming with interrupt disabled, so no need to take the global lock. For interrupt remapping entry allocation, the locking model is: down_read(&dmar_global_lock); /* Find corresponding iommu */ iommu = map_hpet_to_ir(id); if (iommu) /* * Allocate remapping entry and mark entry busy, * the IOMMU won't be hot-removed until the * allocated entry has been released. */ index = alloc_irte(iommu, irq, 1); up_read(&dmar_global_lock); For DMA remmaping driver, we only uses the dmar_global_lock rwsem to protect functions which are only called in process context. For any function which may be called in interrupt context, we will use RCU to protect them in following patches. Signed-off-by: Jiang Liu --- drivers/iommu/dmar.c | 19 +++++- drivers/iommu/intel-iommu.c | 22 ++++--- drivers/iommu/intel_irq_remapping.c | 108 +++++++++++++++++++++++------------ include/linux/dmar.h | 2 + 4 files changed, 103 insertions(+), 48 deletions(-) diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c index 4ae6df2..c9aca88 100644 --- a/drivers/iommu/dmar.c +++ b/drivers/iommu/dmar.c @@ -43,10 +43,19 @@ #include "irq_remapping.h" -/* No locks are needed as DMA remapping hardware unit - * list is constructed at boot time and hotplug of - * these units are not supported by the architecture. +/* + * Assumptions: + * 1) The hotplug framework guarentees that DMAR unit will be hot-added + * before IO devices managed by that unit. + * 2) The hotplug framework guarantees that DMAR unit will be hot-removed + * after IO devices managed by that unit. + * 3) Hotplug events are rare. + * + * Locking rules for DMA and interrupt remapping related global data structures: + * 1) Use dmar_global_lock in process context + * 2) Use RCU in interrupt context */ +DECLARE_RWSEM(dmar_global_lock); LIST_HEAD(dmar_drhd_units); struct acpi_table_header * __initdata dmar_tbl; @@ -565,6 +574,7 @@ int __init detect_intel_iommu(void) { int ret; + down_write(&dmar_global_lock); ret = dmar_table_detect(); if (ret) ret = check_zero_address(); @@ -582,6 +592,7 @@ int __init detect_intel_iommu(void) } early_acpi_os_unmap_memory((void __iomem *)dmar_tbl, dmar_tbl_size); dmar_tbl = NULL; + up_write(&dmar_global_lock); return ret ? 1 : -ENODEV; } @@ -1394,10 +1405,12 @@ static int __init dmar_free_unused_resources(void) if (irq_remapping_enabled || intel_iommu_enabled) return 0; + down_write(&dmar_global_lock); list_for_each_entry_safe(dmaru, dmaru_n, &dmar_drhd_units, list) { list_del(&dmaru->list); dmar_free_drhd(dmaru); } + up_write(&dmar_global_lock); return 0; } diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c index bb98e37..50d639a 100644 --- a/drivers/iommu/intel-iommu.c +++ b/drivers/iommu/intel-iommu.c @@ -3637,11 +3637,13 @@ static int device_notifier(struct notifier_block *nb, if (!domain) return 0; + down_read(&dmar_global_lock); domain_remove_one_dev_info(domain, pdev); if (!(domain->flags & DOMAIN_FLAG_VIRTUAL_MACHINE) && !(domain->flags & DOMAIN_FLAG_STATIC_IDENTITY) && list_empty(&domain->devices)) domain_exit(domain); + up_read(&dmar_global_lock); return 0; } @@ -3659,6 +3661,13 @@ int __init intel_iommu_init(void) /* VT-d is required for a TXT/tboot launch, so enforce that */ force_on = tboot_force_iommu(); + if (iommu_init_mempool()) { + if (force_on) + panic("tboot: Failed to initialize iommu memory\n"); + return -ENOMEM; + } + + down_write(&dmar_global_lock); if (dmar_table_init()) { if (force_on) panic("tboot: Failed to initialize DMAR table\n"); @@ -3681,12 +3690,6 @@ int __init intel_iommu_init(void) if (no_iommu || dmar_disabled) goto out_free_dmar; - if (iommu_init_mempool()) { - if (force_on) - panic("tboot: Failed to initialize iommu memory\n"); - goto out_free_dmar; - } - if (list_empty(&dmar_rmrr_units)) printk(KERN_INFO "DMAR: No RMRR found\n"); @@ -3696,7 +3699,7 @@ int __init intel_iommu_init(void) if (dmar_init_reserved_ranges()) { if (force_on) panic("tboot: Failed to reserve iommu ranges\n"); - goto out_free_mempool; + goto out_free_reserved_range; } init_no_remapping_devices(); @@ -3708,6 +3711,7 @@ int __init intel_iommu_init(void) printk(KERN_ERR "IOMMU: dmar init failed\n"); goto out_free_reserved_range; } + up_write(&dmar_global_lock); printk(KERN_INFO "PCI-DMA: Intel(R) Virtualization Technology for Directed I/O\n"); @@ -3729,10 +3733,10 @@ int __init intel_iommu_init(void) out_free_reserved_range: put_iova_domain(&reserved_iova_list); -out_free_mempool: - iommu_exit_mempool(); out_free_dmar: intel_iommu_free_dmars(); + up_write(&dmar_global_lock); + iommu_exit_mempool(); return ret; } diff --git a/drivers/iommu/intel_irq_remapping.c b/drivers/iommu/intel_irq_remapping.c index ef5f65d..9b17489 100644 --- a/drivers/iommu/intel_irq_remapping.c +++ b/drivers/iommu/intel_irq_remapping.c @@ -38,6 +38,17 @@ static struct ioapic_scope ir_ioapic[MAX_IO_APICS]; static struct hpet_scope ir_hpet[MAX_HPET_TBS]; static int ir_ioapic_num, ir_hpet_num; +/* + * Lock ordering: + * ->dmar_global_lock + * ->irq_2_ir_lock + * ->qi->q_lock + * ->iommu->register_lock + * Note: + * intel_irq_remap_ops.{supported,prepare,enable,disable,reenable} are called + * in single-threaded environment with interrupt disabled, so no need to tabke + * the dmar_global_lock. + */ static DEFINE_RAW_SPINLOCK(irq_2_ir_lock); static int __init parse_ioapics_under_ir(void); @@ -307,12 +318,14 @@ static int set_ioapic_sid(struct irte *irte, int apic) if (!irte) return -1; + down_read(&dmar_global_lock); for (i = 0; i < MAX_IO_APICS; i++) { if (ir_ioapic[i].id == apic) { sid = (ir_ioapic[i].bus << 8) | ir_ioapic[i].devfn; break; } } + up_read(&dmar_global_lock); if (sid == 0) { pr_warning("Failed to set source-id of IOAPIC (%d)\n", apic); @@ -332,12 +345,14 @@ static int set_hpet_sid(struct irte *irte, u8 id) if (!irte) return -1; + down_read(&dmar_global_lock); for (i = 0; i < MAX_HPET_TBS; i++) { if (ir_hpet[i].id == id) { sid = (ir_hpet[i].bus << 8) | ir_hpet[i].devfn; break; } } + up_read(&dmar_global_lock); if (sid == 0) { pr_warning("Failed to set source-id of HPET block (%d)\n", id); @@ -794,10 +809,16 @@ static int __init parse_ioapics_under_ir(void) static int __init ir_dev_scope_init(void) { + int ret; + if (!irq_remapping_enabled) return 0; - return dmar_dev_scope_init(); + down_write(&dmar_global_lock); + ret = dmar_dev_scope_init(); + up_write(&dmar_global_lock); + + return ret; } rootfs_initcall(ir_dev_scope_init); @@ -878,23 +899,27 @@ static int intel_setup_ioapic_entry(int irq, struct io_apic_irq_attr *attr) { int ioapic_id = mpc_ioapic_id(attr->ioapic); - struct intel_iommu *iommu = map_ioapic_to_ir(ioapic_id); + struct intel_iommu *iommu; struct IR_IO_APIC_route_entry *entry; struct irte irte; int index; + down_read(&dmar_global_lock); + iommu = map_ioapic_to_ir(ioapic_id); if (!iommu) { pr_warn("No mapping iommu for ioapic %d\n", ioapic_id); - return -ENODEV; - } - - entry = (struct IR_IO_APIC_route_entry *)route_entry; - - index = alloc_irte(iommu, irq, 1); - if (index < 0) { - pr_warn("Failed to allocate IRTE for ioapic %d\n", ioapic_id); - return -ENOMEM; + index = -ENODEV; + } else { + index = alloc_irte(iommu, irq, 1); + if (index < 0) { + pr_warn("Failed to allocate IRTE for ioapic %d\n", + ioapic_id); + index = -ENOMEM; + } } + up_read(&dmar_global_lock); + if (index < 0) + return index; prepare_irte(&irte, vector, destination); @@ -913,6 +938,7 @@ static int intel_setup_ioapic_entry(int irq, irte.avail, irte.vector, irte.dest_id, irte.sid, irte.sq, irte.svt); + entry = (struct IR_IO_APIC_route_entry *)route_entry; memset(entry, 0, sizeof(*entry)); entry->index2 = (index >> 15) & 0x1; @@ -1043,20 +1069,23 @@ static int intel_msi_alloc_irq(struct pci_dev *dev, int irq, int nvec) struct intel_iommu *iommu; int index; + down_read(&dmar_global_lock); iommu = map_dev_to_ir(dev); if (!iommu) { printk(KERN_ERR "Unable to map PCI %s to iommu\n", pci_name(dev)); - return -ENOENT; + index = -ENOENT; + } else { + index = alloc_irte(iommu, irq, nvec); + if (index < 0) { + printk(KERN_ERR + "Unable to allocate %d IRTE for PCI %s\n", + nvec, pci_name(dev)); + index = -ENOSPC; + } } + up_read(&dmar_global_lock); - index = alloc_irte(iommu, irq, nvec); - if (index < 0) { - printk(KERN_ERR - "Unable to allocate %d IRTE for PCI %s\n", nvec, - pci_name(dev)); - return -ENOSPC; - } return index; } @@ -1064,33 +1093,40 @@ static int intel_msi_setup_irq(struct pci_dev *pdev, unsigned int irq, int index, int sub_handle) { struct intel_iommu *iommu; + int ret = -ENOENT; + down_read(&dmar_global_lock); iommu = map_dev_to_ir(pdev); - if (!iommu) - return -ENOENT; - /* - * setup the mapping between the irq and the IRTE - * base index, the sub_handle pointing to the - * appropriate interrupt remap table entry. - */ - set_irte_irq(irq, iommu, index, sub_handle); + if (iommu) { + /* + * setup the mapping between the irq and the IRTE + * base index, the sub_handle pointing to the + * appropriate interrupt remap table entry. + */ + set_irte_irq(irq, iommu, index, sub_handle); + ret = 0; + } + up_read(&dmar_global_lock); - return 0; + return ret; } static int intel_setup_hpet_msi(unsigned int irq, unsigned int id) { - struct intel_iommu *iommu = map_hpet_to_ir(id); + int ret = -1; + struct intel_iommu *iommu; int index; - if (!iommu) - return -1; - - index = alloc_irte(iommu, irq, 1); - if (index < 0) - return -1; + down_read(&dmar_global_lock); + iommu = map_hpet_to_ir(id); + if (iommu) { + index = alloc_irte(iommu, irq, 1); + if (index >= 0) + ret = 0; + } + up_read(&dmar_global_lock); - return 0; + return ret; } struct irq_remap_ops intel_irq_remap_ops = { diff --git a/include/linux/dmar.h b/include/linux/dmar.h index 4b77fd8..8f06a01 100644 --- a/include/linux/dmar.h +++ b/include/linux/dmar.h @@ -25,6 +25,7 @@ #include #include #include +#include struct acpi_dmar_header; @@ -48,6 +49,7 @@ struct dmar_drhd_unit { struct intel_iommu *iommu; }; +extern struct rw_semaphore dmar_global_lock; extern struct list_head dmar_drhd_units; #define for_each_drhd_unit(drhd) \