From: Yian Chen yian.chen@intel.com
commit 316f92a705a4c2bf4712135180d56f3cca09243a upstream.
Notifier calling chain uses priority to determine the execution order of the notifiers or listeners registered to the chain. PCI bus device hot add utilizes the notification mechanism.
The current code sets low priority (INT_MIN) to Intel dmar_pci_bus_notifier and postpones DMAR decoding after adding new device into IOMMU. The result is that struct device pointer cannot be found in DRHD search for the new device's DMAR/IOMMU. Subsequently, the device is put under the "catch-all" IOMMU instead of the correct one. This could cause system hang when device TLB invalidation is sent to the wrong IOMMU. Invalidation timeout error and hard lockup have been observed and data inconsistency/crush may occur as well.
This patch fixes the issue by setting a positive priority(1) for dmar_pci_bus_notifier while the priority of IOMMU bus notifier uses the default value(0), therefore DMAR decoding will be in advance of DRHD search for a new device to find the correct IOMMU.
Following is a 2-step example that triggers the bug by simulating PCI device hot add behavior in Intel Sapphire Rapids server.
echo 1 > /sys/bus/pci/devices/0000:6a:01.0/remove echo 1 > /sys/bus/pci/rescan
Fixes: 59ce0515cdaf ("iommu/vt-d: Update DRHD/RMRR/ATSR device scope") Cc: stable@vger.kernel.org # v3.15+ Reported-by: Zhang, Bernice bernice.zhang@intel.com Signed-off-by: Jacob Pan jacob.jun.pan@linux.intel.com Signed-off-by: Yian Chen yian.chen@intel.com Link: https://lore.kernel.org/r/20220521002115.1624069-1-yian.chen@intel.com Signed-off-by: Joerg Roedel jroedel@suse.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/iommu/dmar.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/iommu/dmar.c +++ b/drivers/iommu/dmar.c @@ -374,7 +374,7 @@ static int dmar_pci_bus_notifier(struct
static struct notifier_block dmar_pci_bus_nb = { .notifier_call = dmar_pci_bus_notifier, - .priority = INT_MIN, + .priority = 1, };
static struct dmar_drhd_unit *