Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759834Ab2FGEV3 (ORCPT ); Thu, 7 Jun 2012 00:21:29 -0400 Received: from mail-pz0-f46.google.com ([209.85.210.46]:63657 "EHLO mail-pz0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933082Ab2FGEVW (ORCPT ); Thu, 7 Jun 2012 00:21:22 -0400 Message-Id: <20120607040347.474529090@linuxfoundation.org> User-Agent: quilt/0.60-19.1 Date: Thu, 07 Jun 2012 13:04:51 +0900 From: Greg KH To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Joerg Roedel Subject: [ 75/82] iommu/amd: Fix deadlock in ppr-handling error path In-Reply-To: <20120607041406.GA13233@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4018 Lines: 142 3.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Joerg Roedel commit eee53537c476c947bf7faa1c916d2f5a0ae8ec93 upstream. 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. Signed-off-by: Joerg Roedel Signed-off-by: Greg Kroah-Hartman --- drivers/iommu/amd_iommu.c | 73 ++++++++++++++++++++++++++++------------------ 1 file changed, 45 insertions(+), 28 deletions(-) --- a/drivers/iommu/amd_iommu.c +++ b/drivers/iommu/amd_iommu.c @@ -547,26 +547,12 @@ static void iommu_poll_events(struct amd 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(struc 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 am 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; + + 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]; + + /* + * To detect the hardware bug we need to clear the entry + * back to zero. + */ + raw[0] = raw[1] = 0UL; - /* Handle PPR entry */ - iommu_handle_ppr_entry(iommu, head); - - /* Update and refresh ring-buffer state*/ + /* 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); } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/