From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: [PATCHv4] device-assignment: don't touch pci command register Date: Tue, 17 Apr 2012 15:10:42 +0300 Message-ID: <20120417121042.GA24138@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Marcelo Tosatti , Alex Williamson , Jan Kiszka , Avi Kivity To: kvm@vger.kernel.org Return-path: Received: from mx1.redhat.com ([209.132.183.28]:1210 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755451Ab2DQMKc (ORCPT ); Tue, 17 Apr 2012 08:10:32 -0400 Content-Disposition: inline Sender: kvm-owner@vger.kernel.org List-ID: Real command register is under kernel control: it includes bits for triggering SERR, marking BARs as invalid and such which are all under host kernel control. While there's no known bug this triggers - since qemu does its best to make guest state match device state - it seems safer to avoid touching this register as much as possible. With this patch, we don't touch any bits except bus master which is ok to put under guest control and intx mask which kvm interrupt sharing machinery explicitly allows. Note: PCI_STATUS bears looking into as well. Tested-by: Alex Williamson Signed-off-by: Michael S. Tsirkin --- Changes from v3: - use pci_word_test_and_clear_mask to clear bits in a clean way Changes from v2: - whitespace fix Changes from v1: - fix intx mask hw/device-assignment.c | 20 ++++++-------------- 1 files changed, 6 insertions(+), 14 deletions(-) diff --git a/hw/device-assignment.c b/hw/device-assignment.c index 89823f1..17a3a93 100644 --- a/hw/device-assignment.c +++ b/hw/device-assignment.c @@ -501,7 +501,6 @@ static int get_real_device(AssignedDevice *pci_dev, uint16_t r_seg, FILE *f; unsigned long long start, end, size, flags; uint16_t id; - struct stat statbuf; PCIRegion *rp; PCIDevRegions *dev = &pci_dev->real_device; @@ -610,12 +609,8 @@ again: pci_dev->dev.config[2] = id & 0xff; pci_dev->dev.config[3] = (id & 0xff00) >> 8; - /* dealing with virtual function device */ - snprintf(name, sizeof(name), "%sphysfn/", dir); - if (!stat(name, &statbuf)) { - /* always provide the written value on readout */ - assigned_dev_emulate_config_read(pci_dev, PCI_COMMAND, 2); - } + pci_word_test_and_clear_mask(pci_dev->emulate_config_write + PCI_COMMAND, + PCI_COMMAND_MASTER | PCI_COMMAND_INTX_DISABLE); dev->region_number = r; return 0; @@ -782,13 +778,9 @@ static int assign_device(AssignedDevice *dev) "cause host memory corruption if the device issues DMA write " "requests!\n"); } if (dev->features & ASSIGNED_DEVICE_SHARE_INTX_MASK && kvm_has_intx_set_mask()) { assigned_dev_data.flags |= KVM_DEV_ASSIGN_PCI_2_3; - - /* hide host-side INTx masking from the guest */ - dev->emulate_config_read[PCI_COMMAND + 1] |= - PCI_COMMAND_INTX_DISABLE >> 8; } r = kvm_assign_pci_device(kvm_state, &assigned_dev_data); @@ -1631,10 +1624,10 @@ static void reset_assigned_device(DeviceState *dev) } /* - * When a 0 is written to the command register, the device is logically + * When a 0 is written to the bus master register, the device is logically * disconnected from the PCI bus. This avoids further DMA transfers. */ - assigned_dev_pci_write_config(pci_dev, PCI_COMMAND, 0, 2); + assigned_dev_pci_write_config(pci_dev, PCI_COMMAND, 0, 1); } static int assigned_initfn(struct PCIDevice *pci_dev) @@ -1658,7 +1651,6 @@ static int assigned_initfn(struct PCIDevice *pci_dev) * device initialization. */ assigned_dev_emulate_config_read(dev, 0, PCI_CONFIG_SPACE_SIZE); - assigned_dev_direct_config_read(dev, PCI_COMMAND, 2); assigned_dev_direct_config_read(dev, PCI_STATUS, 2); assigned_dev_direct_config_read(dev, PCI_REVISION_ID, 1); assigned_dev_direct_config_read(dev, PCI_CLASS_PROG, 3); -- 1.7.9.111.gf3fb0