Commit 0a584655 authored by Francisco Munoz's avatar Francisco Munoz Committed by Lorenzo Pieralisi
Browse files

PCI: vmd: Fix secondary bus reset for Intel bridges 

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@linux.intel.com


Fixes: 6aab5622 ("PCI: vmd: Clean up domain before enumeration")
Signed-off-by: default avatarFrancisco Munoz <francisco.munoz.ruiz@linux.intel.com>
Signed-off-by: default avatarLorenzo Pieralisi <lpieralisi@kernel.org>
Reviewed-by: default avatarNirmal Patel <nirmal.patel@linux.intel.com>
Reviewed-by: default avatarJonathan Derrick <jonathan.derrick@linux.dev>
parent d899aa66

drivers/pci/controller/vmd.c

+20 −2
Original line number Diff line number Diff line
@@ -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);



	/*