On 2012-04-17 14:10, Michael S. Tsirkin wrote:
> 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 <alex.williamson@xxxxxxxxxx>
> Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
> ---
>
> 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);
Acked-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
--
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux
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