From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759969Ab2FAOGD (ORCPT ); Fri, 1 Jun 2012 10:06:03 -0400 Received: from db3ehsobe006.messaging.microsoft.com ([213.199.154.144]:20883 "EHLO db3outboundpool.messaging.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754623Ab2FAOFS (ORCPT ); Fri, 1 Jun 2012 10:05:18 -0400 X-Forefront-Antispam-Report: CIP:163.181.249.108;KIP:(null);UIP:(null);IPV:NLI;H:ausb3twp01.amd.com;RD:none;EFVD:NLI X-SpamScore: 0 X-BigFish: VPS0(zzzz1202hzz8275bh8275dhz2dh668h839hd24he5bhf0ah) X-WSS-ID: 0M4XZ4K-01-7D4-02 X-M-MSG: From: Joerg Roedel To: CC: , Joerg Roedel Subject: [PATCH 2/2] iommu/amd: Fix deadlock in ppr-handling error path Date: Fri, 1 Jun 2012 16:05:01 +0200 Message-ID: <1338559501-15478-2-git-send-email-joerg.roedel@amd.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1338559501-15478-1-git-send-email-joerg.roedel@amd.com> References: <1338559501-15478-1-git-send-email-joerg.roedel@amd.com> MIME-Version: 1.0 Content-Type: text/plain X-OriginatorOrg: amd.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In the error path of the ppr_notifer it can happen that the iommu->lock is taken recursivly. This patch fixes the problem by releasing the iommu->lock before any notifier is invoked. This also requires to move the erratum workaround for the ppr-log (interrupt may be faster than data in the log) one function up. Cc: stable@vger.kernel.org # v3.3, v3.4 Signed-off-by: Joerg Roedel --- drivers/iommu/amd_iommu.c | 71 ++++++++++++++++++++++++++++----------------- 1 file changed, 44 insertions(+), 27 deletions(-) diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c index d90a421..a2e418c 100644 --- a/drivers/iommu/amd_iommu.c +++ b/drivers/iommu/amd_iommu.c @@ -547,26 +547,12 @@ static void iommu_poll_events(struct amd_iommu *iommu) spin_unlock_irqrestore(&iommu->lock, flags); } -static void iommu_handle_ppr_entry(struct amd_iommu *iommu, u32 head) +static void iommu_handle_ppr_entry(struct amd_iommu *iommu, u64 *raw) { struct amd_iommu_fault fault; - volatile u64 *raw; - int i; INC_STATS_COUNTER(pri_requests); - raw = (u64 *)(iommu->ppr_log + head); - - /* - * Hardware bug: Interrupt may arrive before the entry is written to - * memory. If this happens we need to wait for the entry to arrive. - */ - for (i = 0; i < LOOP_TIMEOUT; ++i) { - if (PPR_REQ_TYPE(raw[0]) != 0) - break; - udelay(1); - } - if (PPR_REQ_TYPE(raw[0]) != PPR_REQ_FAULT) { pr_err_ratelimited("AMD-Vi: Unknown PPR request received\n"); return; @@ -578,12 +564,6 @@ static void iommu_handle_ppr_entry(struct amd_iommu *iommu, u32 head) fault.tag = PPR_TAG(raw[0]); fault.flags = PPR_FLAGS(raw[0]); - /* - * To detect the hardware bug we need to clear the entry - * to back to zero. - */ - raw[0] = raw[1] = 0; - atomic_notifier_call_chain(&ppr_notifier, 0, &fault); } @@ -595,25 +575,62 @@ static void iommu_poll_ppr_log(struct amd_iommu *iommu) if (iommu->ppr_log == NULL) return; + /* enable ppr interrupts again */ + writel(MMIO_STATUS_PPR_INT_MASK, iommu->mmio_base + MMIO_STATUS_OFFSET); + spin_lock_irqsave(&iommu->lock, flags); head = readl(iommu->mmio_base + MMIO_PPR_HEAD_OFFSET); tail = readl(iommu->mmio_base + MMIO_PPR_TAIL_OFFSET); while (head != tail) { + volatile u64 *raw; + u64 entry[2]; + int i; - /* Handle PPR entry */ - iommu_handle_ppr_entry(iommu, head); + raw = (u64 *)(iommu->ppr_log + head); + + /* + * Hardware bug: Interrupt may arrive before the entry is + * written to memory. If this happens we need to wait for the + * entry to arrive. + */ + for (i = 0; i < LOOP_TIMEOUT; ++i) { + if (PPR_REQ_TYPE(raw[0]) != 0) + break; + udelay(1); + } + + /* Avoid memcpy function-call overhead */ + entry[0] = raw[0]; + entry[1] = raw[1]; - /* Update and refresh ring-buffer state*/ + /* + * To detect the hardware bug we need to clear the entry + * back to zero. + */ + raw[0] = raw[1] = 0UL; + + /* Update head pointer of hardware ring-buffer */ head = (head + PPR_ENTRY_SIZE) % PPR_LOG_SIZE; writel(head, iommu->mmio_base + MMIO_PPR_HEAD_OFFSET); + + /* + * Release iommu->lock because ppr-handling might need to + * re-aquire it + */ + spin_unlock_irqrestore(&iommu->lock, flags); + + /* Handle PPR entry */ + iommu_handle_ppr_entry(iommu, entry); + + spin_lock_irqsave(&iommu->lock, flags); + + /* Refresh ring-buffer information */ + head = readl(iommu->mmio_base + MMIO_PPR_HEAD_OFFSET); tail = readl(iommu->mmio_base + MMIO_PPR_TAIL_OFFSET); } - /* enable ppr interrupts again */ - writel(MMIO_STATUS_PPR_INT_MASK, iommu->mmio_base + MMIO_STATUS_OFFSET); - spin_unlock_irqrestore(&iommu->lock, flags); } -- 1.7.9.5