From: Mukesh R <[email protected]> Hyper-V Discrete Device Assignment (DDA) does not support legacy (INTX) interrupts. When PCI_INTERRUPT_PIN is read, the pci-hyperv controller, which captures configuration space accesses, returns 0 to the caller.
However, the current code only captures 8bit read access, thus 16bit/32bit are missed, forwarded to the host/HW, and may yield a non zero value. This fix addresses this issue, and makes sure that PCI_INTERRUPT_PIN is hardwired to 0, while the other bytes, are those returned by the host/HW. Signed-off-by: Asher Kariv <[email protected]> Signed-off-by: Mukesh R <[email protected]> Signed-off-by: Wei Liu <[email protected]> --- drivers/pci/controller/pci-hyperv.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c index 89816a2bd7cd..e6db82413add 100644 --- a/drivers/pci/controller/pci-hyperv.c +++ b/drivers/pci/controller/pci-hyperv.c @@ -1240,6 +1240,16 @@ static void _hv_pcifront_read_config(struct hv_pci_dev *hpdev, int where, mb(); } spin_unlock_irqrestore(&hbus->config_lock, flags); + + /* + * Make sure PCI_INTERRUPT_PIN is hard-wired to 0, since it + * may be read using a 32bit read, which is skipped by the + * above emulation. + */ + if (where <= PCI_INTERRUPT_PIN && + PCI_INTERRUPT_PIN < (where + size)) + *((char *)val + PCI_INTERRUPT_PIN - where) = 0; + } } else { dev_err(dev, "Attempt to read beyond a function's config space.\n"); } -- 2.53.0
