From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752037Ab1ABHVz (ORCPT ); Sun, 2 Jan 2011 02:21:55 -0500 Received: from mail.windriver.com ([147.11.1.11]:34264 "EHLO mail.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751635Ab1ABHVv (ORCPT ); Sun, 2 Jan 2011 02:21:51 -0500 From: Paul Gortmaker To: stable@kernel.org, linux-kernel@vger.kernel.org Cc: stable-review@kernel.org, Ben Hutchings , Jesse Barnes , Paul Gortmaker Subject: [34-longterm 035/260] PCI: MSI: Remove unsafe and unnecessary hardware access Date: Sun, 2 Jan 2011 02:15:31 -0500 Message-Id: <1293952756-15010-36-git-send-email-paul.gortmaker@windriver.com> X-Mailer: git-send-email 1.7.3.3 In-Reply-To: <1293952756-15010-1-git-send-email-paul.gortmaker@windriver.com> References: <1293952756-15010-1-git-send-email-paul.gortmaker@windriver.com> X-OriginalArrivalTime: 02 Jan 2011 07:20:44.0600 (UTC) FILETIME=[91D43B80:01CBAA4D] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Ben Hutchings commit fcd097f31a6ee207cc0c3da9cccd2a86d4334785 upstream. During suspend on an SMP system, {read,write}_msi_msg_desc() may be called to mask and unmask interrupts on a device that is already in a reduced power state. At this point memory-mapped registers including MSI-X tables are not accessible, and config space may not be fully functional either. While a device is in a reduced power state its interrupts are effectively masked and its MSI(-X) state will be restored when it is brought back to D0. Therefore these functions can simply read and write msi_desc::msg for devices not in D0. Further, read_msi_msg_desc() should only ever be used to update a previously written message, so it can always read msi_desc::msg and never needs to touch the hardware. Tested-by: "Michael Chan" Signed-off-by: Ben Hutchings Signed-off-by: Jesse Barnes Signed-off-by: Paul Gortmaker --- drivers/pci/msi.c | 34 +++++++++++----------------------- 1 files changed, 11 insertions(+), 23 deletions(-) diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c index 77b68ea..03f04dc 100644 --- a/drivers/pci/msi.c +++ b/drivers/pci/msi.c @@ -196,30 +196,15 @@ void unmask_msi_irq(unsigned int irq) void read_msi_msg_desc(struct irq_desc *desc, struct msi_msg *msg) { struct msi_desc *entry = get_irq_desc_msi(desc); - if (entry->msi_attrib.is_msix) { - void __iomem *base = entry->mask_base + - entry->msi_attrib.entry_nr * PCI_MSIX_ENTRY_SIZE; - msg->address_lo = readl(base + PCI_MSIX_ENTRY_LOWER_ADDR); - msg->address_hi = readl(base + PCI_MSIX_ENTRY_UPPER_ADDR); - msg->data = readl(base + PCI_MSIX_ENTRY_DATA); - } else { - struct pci_dev *dev = entry->dev; - int pos = entry->msi_attrib.pos; - u16 data; + /* We do not touch the hardware (which may not even be + * accessible at the moment) but return the last message + * written. Assert that this is valid, assuming that + * valid messages are not all-zeroes. */ + BUG_ON(!(entry->msg.address_hi | entry->msg.address_lo | + entry->msg.data)); - pci_read_config_dword(dev, msi_lower_address_reg(pos), - &msg->address_lo); - if (entry->msi_attrib.is_64) { - pci_read_config_dword(dev, msi_upper_address_reg(pos), - &msg->address_hi); - pci_read_config_word(dev, msi_data_reg(pos, 1), &data); - } else { - msg->address_hi = 0; - pci_read_config_word(dev, msi_data_reg(pos, 0), &data); - } - msg->data = data; - } + *msg = entry->msg; } void read_msi_msg(unsigned int irq, struct msi_msg *msg) @@ -232,7 +217,10 @@ void read_msi_msg(unsigned int irq, struct msi_msg *msg) void write_msi_msg_desc(struct irq_desc *desc, struct msi_msg *msg) { struct msi_desc *entry = get_irq_desc_msi(desc); - if (entry->msi_attrib.is_msix) { + + if (entry->dev->current_state != PCI_D0) { + /* Don't touch the hardware now */ + } else if (entry->msi_attrib.is_msix) { void __iomem *base; base = entry->mask_base + entry->msi_attrib.entry_nr * PCI_MSIX_ENTRY_SIZE; -- 1.7.3.3