[PATCH 2/2] iommu/vt-d: Fix NULL domain on device release

[Lu Baolu <baolu.lu@linux.intel.com>]

In the kdump kernel, the IOMMU operates in deferred_attach mode. In this
mode, info->domain may not yet be assigned by the time the release_device
function is called. It leads to the following crash in the crash kernel:

    BUG: kernel NULL pointer dereference, address: 000000000000003c
    ...
    RIP: 0010:do_raw_spin_lock+0xa/0xa0
    ...
    _raw_spin_lock_irqsave+0x1b/0x30
    intel_iommu_release_device+0x96/0x170
    iommu_deinit_device+0x39/0xf0
    __iommu_group_remove_device+0xa0/0xd0
    iommu_bus_notifier+0x55/0xb0
    notifier_call_chain+0x5a/0xd0
    blocking_notifier_call_chain+0x41/0x60
    bus_notify+0x34/0x50
    device_del+0x269/0x3d0
    pci_remove_bus_device+0x77/0x100
    p2sb_bar+0xae/0x1d0
    ...
    i801_probe+0x423/0x740

Use the release_domain mechanism to fix it.

Fixes: 586081d3f6b1 ("iommu/vt-d: Remove DEFER_DEVICE_DOMAIN_INFO")
Reported-by: Eric Badger <ebadger@purestorage.com>
Closes: https://lore.kernel.org/r/20240113181713.1817855-1-ebadger@purestorage.com
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 drivers/iommu/intel/iommu.c | 26 +-------------------------
 1 file changed, 1 insertion(+), 25 deletions(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 61bb35046ea4..2c04ea90d22f 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -3798,30 +3798,6 @@ static void domain_context_clear(struct device_domain_info *info)
 			       &domain_context_clear_one_cb, info);
 }
 
-static void dmar_remove_one_dev_info(struct device *dev)
-{
-	struct device_domain_info *info = dev_iommu_priv_get(dev);
-	struct dmar_domain *domain = info->domain;
-	struct intel_iommu *iommu = info->iommu;
-	unsigned long flags;
-
-	if (!dev_is_real_dma_subdevice(info->dev)) {
-		if (dev_is_pci(info->dev) && sm_supported(iommu))
-			intel_pasid_tear_down_entry(iommu, info->dev,
-					IOMMU_NO_PASID, false);
-
-		iommu_disable_pci_caps(info);
-		domain_context_clear(info);
-	}
-
-	spin_lock_irqsave(&domain->lock, flags);
-	list_del(&info->link);
-	spin_unlock_irqrestore(&domain->lock, flags);
-
-	domain_detach_iommu(domain, iommu);
-	info->domain = NULL;
-}
-
 /*
  * Clear the page table pointer in context or pasid table entries so that
  * all DMA requests without PASID from the device are blocked. If the page
@@ -4348,7 +4324,6 @@ static void intel_iommu_release_device(struct device *dev)
 {
 	struct device_domain_info *info = dev_iommu_priv_get(dev);
 
-	dmar_remove_one_dev_info(dev);
 	intel_pasid_free_table(dev);
 	intel_iommu_debugfs_remove_dev(info);
 	kfree(info);
@@ -4839,6 +4814,7 @@ static const struct iommu_dirty_ops intel_dirty_ops = {
 
 const struct iommu_ops intel_iommu_ops = {
 	.blocked_domain		= &blocking_domain,
+	.release_domain		= &blocking_domain,
 	.capable		= intel_iommu_capable,
 	.hw_info		= intel_iommu_hw_info,
 	.domain_alloc		= intel_iommu_domain_alloc,
-- 
2.34.1