From: Francisco Munoz <francisco.munoz.ruiz@xxxxxxxxxxxxxxx> [ Upstream commit 0a584655ef89541dae4d48d2c523b1480ae80284 ] The reset was never applied in the current implementation because Intel Bridges owned by VMD are parentless. Internally, pci_reset_bus() applies a reset to the parent of the PCI device supplied as argument, but in this case it failed because there wasn't a parent. In more detail, this change allows the VMD driver to enumerate NVMe devices in pass-through configurations when guest reboots are performed. There was an attempted to fix this, but later we discovered that the code inside pci_reset_bus() wasn’t triggering secondary bus resets. Therefore, we updated the parameters passed to it, and now NVMe SSDs attached to VMD bridges are properly enumerated in VT-d pass-through scenarios. Link: https://lore.kernel.org/r/20221206001637.4744-1-francisco.munoz.ruiz@xxxxxxxxxxxxxxx Fixes: 6aab5622296b ("PCI: vmd: Clean up domain before enumeration") Signed-off-by: Francisco Munoz <francisco.munoz.ruiz@xxxxxxxxxxxxxxx> Signed-off-by: Lorenzo Pieralisi <lpieralisi@xxxxxxxxxx> Reviewed-by: Nirmal Patel <nirmal.patel@xxxxxxxxxxxxxxx> Reviewed-by: Jonathan Derrick <jonathan.derrick@xxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/pci/controller/vmd.c | 22 ++++++++++++++++++++-- 1 file changed, 20 insertions(+), 2 deletions(-) diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c index 98e0746e681c..769eedeb8802 100644 --- a/drivers/pci/controller/vmd.c +++ b/drivers/pci/controller/vmd.c @@ -719,6 +719,7 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features) resource_size_t offset[2] = {0}; resource_size_t membar2_offset = 0x2000; struct pci_bus *child; + struct pci_dev *dev; int ret; /* @@ -859,8 +860,25 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features) pci_scan_child_bus(vmd->bus); vmd_domain_reset(vmd); - list_for_each_entry(child, &vmd->bus->children, node) - pci_reset_bus(child->self); + + /* When Intel VMD is enabled, the OS does not discover the Root Ports + * owned by Intel VMD within the MMCFG space. pci_reset_bus() applies + * a reset to the parent of the PCI device supplied as argument. This + * is why we pass a child device, so the reset can be triggered at + * the Intel bridge level and propagated to all the children in the + * hierarchy. + */ + list_for_each_entry(child, &vmd->bus->children, node) { + if (!list_empty(&child->devices)) { + dev = list_first_entry(&child->devices, + struct pci_dev, bus_list); + if (pci_reset_bus(dev)) + pci_warn(dev, "can't reset device: %d\n", ret); + + break; + } + } + pci_assign_unassigned_bus_resources(vmd->bus); /* -- 2.35.1
