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PCI: vmd: Fix secondary bus reset for Intel bridges

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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: 6aab562229 ("PCI: vmd: Clean up domain before enumeration")
Signed-off-by: Francisco Munoz <francisco.munoz.ruiz@linux.intel.com>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Reviewed-by: Nirmal Patel <nirmal.patel@linux.intel.com>
Reviewed-by: Jonathan Derrick <jonathan.derrick@linux.dev>
This commit is contained in:
Francisco Munoz 2022-12-05 17:16:37 -07:00 • committed by Lorenzo Pieralisi
parent d899aa6684
commit 0a584655ef
1 changed files with 20 additions and 2 deletions
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22
drivers/pci/controller/vmd.c
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@ -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);
/*