On 6/10/25 02:45, Nicolin Chen wrote:
Per PCIe r6.3, sec 10.3.1 IMPLEMENTATION NOTE, software should disable ATS
before initiating a Function Level Reset.
Call iommu_dev_reset_prepare() before FLR and iommu_dev_reset_done() after,
in the two FLR Functions. This will dock the device at IOMMU_DOMAIN_BLOCKED
during the FLR function, which should allow the IOMMU driver to pause DMA
traffic and invode pci_disable_ats() and pci_enable_ats() respectively.
Add a warning if ATS isn't disabled, in which case IOMMU driver should fix
itself to disable ATS following the design in iommu_dev_reset_prepare().
Signed-off-by: Nicolin Chen<nicolinc@xxxxxxxxxx>
---
drivers/pci/pci.c | 42 ++++++++++++++++++++++++++++++++++++++----
1 file changed, 38 insertions(+), 4 deletions(-)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index e9448d55113b..61535435bde1 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -13,6 +13,7 @@
#include <linux/delay.h>
#include <linux/dmi.h>
#include <linux/init.h>
+#include <linux/iommu.h>
#include <linux/msi.h>
#include <linux/of.h>
#include <linux/pci.h>
@@ -4518,13 +4519,26 @@ EXPORT_SYMBOL(pci_wait_for_pending_transaction);
*/
int pcie_flr(struct pci_dev *dev)
{
+ int ret = 0;
+
if (!pci_wait_for_pending_transaction(dev))
pci_err(dev, "timed out waiting for pending transaction; performing function level reset anyway\n");
+ /*
+ * Per PCIe r6.3, sec 10.3.1 IMPLEMENTATION NOTE, software disables ATS
+ * before initiating a Function Level Reset. So notify the iommu driver
+ * that actually enabled ATS. Have to call it after waiting for pending
+ * DMA transaction.
+ */
+ if (iommu_dev_reset_prepare(&dev->dev))
+ pci_err(dev, "failed to stop IOMMU\n");
Need to abort here?
Thanks,
baolu
