Re: [PATCH v5 02/23] PCI: Enable bridge's I/O and MEM access for hotplugged devices
From: Bjorn Helgaas <helgaas@kernel.org>
Date: 2019-09-27 22:04:27
Also in:
linux-pci
On Fri, Aug 16, 2019 at 07:50:40PM +0300, Sergey Miroshnichenko wrote:
The PCI_COMMAND_IO and PCI_COMMAND_MEMORY bits of the bridge must be updated not only when enabling the bridge for the first time, but also if a hotplugged device requests these types of resources.
Yeah, this assumption that pci_is_enabled() means PCI_COMMAND_IO and PCI_COMMAND_MEMORY are set correctly even though we may now need *different* settings than when we incremented pdev->enable_cnt is quite broken.
quoted hunk ↗ jump to hunk
Originally these bits were set by the pci_enable_device_flags() only, which exits early if the bridge is already pci_is_enabled(). So if the bridge was empty initially (an edge case), then hotplugged devices fail to IO/MEM. Signed-off-by: Sergey Miroshnichenko <redacted> --- drivers/pci/pci.c | 8 ++++++++ 1 file changed, 8 insertions(+)diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index e7f8c354e644..61d951766087 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c@@ -1652,6 +1652,14 @@ static void pci_enable_bridge(struct pci_dev *dev) pci_enable_bridge(bridge); if (pci_is_enabled(dev)) { + int i, bars = 0; + + for (i = PCI_BRIDGE_RESOURCES; i < DEVICE_COUNT_RESOURCE; i++) { + if (dev->resource[i].flags & (IORESOURCE_MEM | IORESOURCE_IO)) + bars |= (1 << i); + } + do_pci_enable_device(dev, bars); + if (!dev->is_busmaster) pci_set_master(dev); mutex_unlock(&dev->enable_mutex);-- 2.21.0