In practice, guests don't generate config requests that cross a word boundary, so the logic to detect command word access is correct because PCI_COMMAND is 0x4. But depending on this is tricky, further, it will break with guests that do try to generate a misaligned access as we pass it to devices without splitting.
Better to use the generic range_covers_byte for this. Signed-off-by: Michael S. Tsirkin <m...@redhat.com> --- hw/virtio-pci.c | 18 +++++++++--------- 1 files changed, 9 insertions(+), 9 deletions(-) diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c index d685243..4f770fe 100644 --- a/hw/virtio-pci.c +++ b/hw/virtio-pci.c @@ -27,6 +27,7 @@ #include "kvm.h" #include "blockdev.h" #include "virtio-pci.h" +#include "range.h" /* from Linux's linux/virtio_pci.h */ @@ -516,17 +517,16 @@ static void virtio_write_config(PCIDevice *pci_dev, uint32_t address, { VirtIOPCIProxy *proxy = DO_UPCAST(VirtIOPCIProxy, pci_dev, pci_dev); - if (PCI_COMMAND == address) { - if (!(val & PCI_COMMAND_MASTER)) { - if (!(proxy->flags & VIRTIO_PCI_FLAG_BUS_MASTER_BUG)) { - virtio_pci_stop_ioeventfd(proxy); - virtio_set_status(proxy->vdev, - proxy->vdev->status & ~VIRTIO_CONFIG_S_DRIVER_OK); - } - } + pci_default_write_config(pci_dev, address, val, len); + + if (range_covers_byte(address, len, PCI_COMMAND) && + !(pci_dev->config[PCI_COMMAND] & PCI_COMMAND_MASTER) && + !(proxy->flags & VIRTIO_PCI_FLAG_BUS_MASTER_BUG)) { + virtio_pci_stop_ioeventfd(proxy); + virtio_set_status(proxy->vdev, + proxy->vdev->status & ~VIRTIO_CONFIG_S_DRIVER_OK); } - pci_default_write_config(pci_dev, address, val, len); msix_write_config(pci_dev, address, val, len); } -- 1.7.5.53.gc233e