[PATCH v2 2/3] iommu/vt-d: Check FL and SL capability sanity in scalable mode

[Lu Baolu]

An iommu domain could be allocated and mapped before it's attached to any
device. This requires that in scalable mode, when the domain is allocated,
the format (FL or SL) of the page table must be determined. In order to
achieve this, the platform should support consistent SL or FL capabilities
on all IOMMU's. This adds a check for this and aborts IOMMU probing if it
doesn't meet this requirement.

Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
---
 drivers/iommu/intel/cap_audit.h |  1 +
 drivers/iommu/intel/cap_audit.c | 13 +++++++++++++
 2 files changed, 14 insertions(+)

diff --git a/drivers/iommu/intel/cap_audit.h b/drivers/iommu/intel/cap_audit.h
index 74cfccae0e81..d07b75938961 100644
--- a/drivers/iommu/intel/cap_audit.h
+++ b/drivers/iommu/intel/cap_audit.h
@@ -111,6 +111,7 @@ bool intel_cap_smts_sanity(void);
 bool intel_cap_pasid_sanity(void);
 bool intel_cap_nest_sanity(void);
 bool intel_cap_flts_sanity(void);
+bool intel_cap_slts_sanity(void);
 
 static inline bool scalable_mode_support(void)
 {
diff --git a/drivers/iommu/intel/cap_audit.c b/drivers/iommu/intel/cap_audit.c
index b12e421a2f1a..040e4ae0e42b 100644
--- a/drivers/iommu/intel/cap_audit.c
+++ b/drivers/iommu/intel/cap_audit.c
@@ -163,6 +163,14 @@ static int cap_audit_static(struct intel_iommu *iommu, enum cap_audit_type type)
 			check_irq_capabilities(iommu, i);
 	}
 
+	/*
+	 * If the system is sane to support scalable mode, either SL or FL
+	 * should be sane.
+	 */
+	if (intel_cap_smts_sanity() &&
+	    !intel_cap_flts_sanity() && !intel_cap_slts_sanity())
+		return -EFAULT;
+
 out:
 	rcu_read_unlock();
 	return 0;
@@ -203,3 +211,8 @@ bool intel_cap_flts_sanity(void)
 {
 	return ecap_flts(intel_iommu_ecap_sanity);
 }
+
+bool intel_cap_slts_sanity(void)
+{
+	return ecap_slts(intel_iommu_ecap_sanity);
+}
-- 
2.25.1