diff options
| -rw-r--r-- | drivers/pci/controller/pci-hyperv.c | 17 |
1 files changed, 11 insertions, 6 deletions
diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c index 7aea0b7a994b..cf2fe5754fde 100644 --- a/drivers/pci/controller/pci-hyperv.c +++ b/drivers/pci/controller/pci-hyperv.c @@ -2103,12 +2103,17 @@ static void prepopulate_bars(struct hv_pcibus_device *hbus) } } if (high_size <= 1 && low_size <= 1) { - /* Set the memory enable bit. */ - _hv_pcifront_read_config(hpdev, PCI_COMMAND, 2, - &command); - command |= PCI_COMMAND_MEMORY; - _hv_pcifront_write_config(hpdev, PCI_COMMAND, 2, - command); + /* + * No need to set the PCI_COMMAND_MEMORY bit as + * the core PCI driver doesn't require the bit + * to be pre-set. Actually here we intentionally + * keep the bit off so that the PCI BAR probing + * in the core PCI driver doesn't cause Hyper-V + * to unnecessarily unmap/map the virtual BARs + * from/to the physical BARs multiple times. + * This reduces the VM boot time significantly + * if the BAR sizes are huge. + */ break; } } |