[PATCH 1/1] iommu/vt-d: Restore context entry setup order for aliased devices

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

Commit 2031c469f816 ("iommu/vt-d: Add support for static identity domain")
changed the context entry setup during domain attachment from a
set-and-check policy to a clear-and-reset approach. This inadvertently
introduced a regression affecting PCI aliased devices behind PCIe-to-PCI
bridges.

Specifically, keyboard and touchpad stopped working on several Apple
Macbooks with below messages:

 kernel: platform pxa2xx-spi.3: Adding to iommu group 20
 kernel: input: Apple SPI Keyboard as
 /devices/pci0000:00/0000:00:1e.3/pxa2xx-spi.3/spi_master/spi2/spi-APP000D:00/input/input0
 kernel: DMAR: DRHD: handling fault status reg 3
 kernel: DMAR: [DMA Read NO_PASID] Request device [00:1e.3] fault addr
 0xffffa000 [fault reason 0x06] PTE Read access is not set
 kernel: DMAR: DRHD: handling fault status reg 3
 kernel: DMAR: [DMA Read NO_PASID] Request device [00:1e.3] fault addr
 0xffffa000 [fault reason 0x06] PTE Read access is not set
 kernel: applespi spi-APP000D:00: Error writing to device: 01 0e 00 00
 kernel: DMAR: DRHD: handling fault status reg 3
 kernel: DMAR: [DMA Read NO_PASID] Request device [00:1e.3] fault addr
 0xffffa000 [fault reason 0x06] PTE Read access is not set
 kernel: DMAR: DRHD: handling fault status reg 3
 kernel: applespi spi-APP000D:00: Error writing to device: 01 0e 00 00

Fix this by restoring the previous context setup order.

Fixes: 2031c469f816 ("iommu/vt-d: Add support for static identity domain")
Closes: https://lore.kernel.org/all/4dada48a-c5dd-4c30-9c85-5b03b0aa01f0@bfh.ch/
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 drivers/iommu/intel/iommu.c  | 11 +++++++++++
 drivers/iommu/intel/iommu.h  |  1 +
 drivers/iommu/intel/nested.c |  4 ++--
 3 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 49530d5d8c85..7aa3932251b2 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -1809,6 +1809,7 @@ static int dmar_domain_attach_device(struct dmar_domain *domain,
 		return ret;
 
 	info->domain = domain;
+	info->domain_attached = true;
 	spin_lock_irqsave(&domain->lock, flags);
 	list_add(&info->link, &domain->devices);
 	spin_unlock_irqrestore(&domain->lock, flags);
@@ -3206,6 +3207,10 @@ void device_block_translation(struct device *dev)
 	struct intel_iommu *iommu = info->iommu;
 	unsigned long flags;
 
+	/* Device in DMA blocking state. Noting to do. */
+	if (!info->domain_attached)
+		return;
+
 	if (info->domain)
 		cache_tag_unassign_domain(info->domain, dev, IOMMU_NO_PASID);
 
@@ -3217,6 +3222,9 @@ void device_block_translation(struct device *dev)
 			domain_context_clear(info);
 	}
 
+	/* Device now in DMA blocking state. */
+	info->domain_attached = false;
+
 	if (!info->domain)
 		return;
 
@@ -4302,6 +4310,9 @@ static int identity_domain_attach_dev(struct iommu_domain *domain, struct device
 	else
 		ret = device_setup_pass_through(dev);
 
+	if (!ret)
+		info->domain_attached = true;
+
 	return ret;
 }
 
diff --git a/drivers/iommu/intel/iommu.h b/drivers/iommu/intel/iommu.h
index cbfb8bb4c94a..3ddbcc603de2 100644
--- a/drivers/iommu/intel/iommu.h
+++ b/drivers/iommu/intel/iommu.h
@@ -774,6 +774,7 @@ struct device_domain_info {
 	u8 ats_supported:1;
 	u8 ats_enabled:1;
 	u8 dtlb_extra_inval:1;	/* Quirk for devices need extra flush */
+	u8 domain_attached:1;	/* Device has domain attached */
 	u8 ats_qdep;
 	unsigned int iopf_refcount;
 	struct device *dev; /* it's NULL for PCIe-to-PCI bridge */
diff --git a/drivers/iommu/intel/nested.c b/drivers/iommu/intel/nested.c
index d2a94025d0a0..fc312f649f9e 100644
--- a/drivers/iommu/intel/nested.c
+++ b/drivers/iommu/intel/nested.c
@@ -27,8 +27,7 @@ static int intel_nested_attach_dev(struct iommu_domain *domain,
 	unsigned long flags;
 	int ret = 0;
 
-	if (info->domain)
-		device_block_translation(dev);
+	device_block_translation(dev);
 
 	if (iommu->agaw < dmar_domain->s2_domain->agaw) {
 		dev_err_ratelimited(dev, "Adjusted guest address width not compatible\n");
@@ -66,6 +65,7 @@ static int intel_nested_attach_dev(struct iommu_domain *domain,
 		goto disable_iopf;
 
 	info->domain = dmar_domain;
+	info->domain_attached = true;
 	spin_lock_irqsave(&dmar_domain->lock, flags);
 	list_add(&info->link, &dmar_domain->devices);
 	spin_unlock_irqrestore(&dmar_domain->lock, flags);
-- 
2.43.0