[PATCH v3 04/14] iommu/ioasid: Support setting system-wide capacity

[Jacob Pan <jacob.pan.linux@gmail.com>]

IOASID is a system-wide resource that could vary on different systems.
The default capacity is 20 bits as defined in the PCI-E specifications.
This patch adds a function to allow adjusting system IOASID capacity.
For VT-d this is set during boot as part of the Intel IOMMU
initialization.

Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
---
 drivers/iommu/intel/iommu.c |  5 +++++
 drivers/iommu/ioasid.c      | 20 ++++++++++++++++++++
 include/linux/ioasid.h      | 11 +++++++++++
 3 files changed, 36 insertions(+)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 18ed3b3c70d7..e7bcb299e51e 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -42,6 +42,7 @@
 #include <linux/crash_dump.h>
 #include <linux/numa.h>
 #include <linux/swiotlb.h>
+#include <linux/ioasid.h>
 #include <asm/irq_remapping.h>
 #include <asm/cacheflush.h>
 #include <asm/iommu.h>
@@ -3331,6 +3332,10 @@ static int __init init_dmars(void)
 	if (ret)
 		goto free_iommu;
 
+	/* PASID is needed for scalable mode irrespective to SVM */
+	if (intel_iommu_sm)
+		ioasid_install_capacity(intel_pasid_max_id);
+
 	/*
 	 * for each drhd
 	 *   enable fault log
diff --git a/drivers/iommu/ioasid.c b/drivers/iommu/ioasid.c
index 6cfbdfb492e0..4277cb17e15b 100644
--- a/drivers/iommu/ioasid.c
+++ b/drivers/iommu/ioasid.c
@@ -10,6 +10,10 @@
 #include <linux/spinlock.h>
 #include <linux/xarray.h>
 
+/* Default to PCIe standard 20 bit PASID */
+#define PCI_PASID_MAX 0x100000
+static ioasid_t ioasid_capacity = PCI_PASID_MAX;
+static ioasid_t ioasid_capacity_avail = PCI_PASID_MAX;
 struct ioasid_data {
 	ioasid_t id;
 	struct ioasid_set *set;
@@ -17,6 +21,22 @@ struct ioasid_data {
 	struct rcu_head rcu;
 };
 
+void ioasid_install_capacity(ioasid_t total)
+{
+	if (ioasid_capacity && ioasid_capacity != PCI_PASID_MAX) {
+		pr_warn("IOASID capacity is already set.\n");
+		return;
+	}
+	ioasid_capacity = ioasid_capacity_avail = total;
+}
+EXPORT_SYMBOL_GPL(ioasid_install_capacity);
+
+ioasid_t ioasid_get_capacity(void)
+{
+	return ioasid_capacity;
+}
+EXPORT_SYMBOL_GPL(ioasid_get_capacity);
+
 /*
  * struct ioasid_allocator_data - Internal data structure to hold information
  * about an allocator. There are two types of allocators:
diff --git a/include/linux/ioasid.h b/include/linux/ioasid.h
index c7f649fa970a..7fc320656be2 100644
--- a/include/linux/ioasid.h
+++ b/include/linux/ioasid.h
@@ -32,6 +32,8 @@ struct ioasid_allocator_ops {
 #define DECLARE_IOASID_SET(name) struct ioasid_set name = { 0 }
 
 #if IS_ENABLED(CONFIG_IOASID)
+void ioasid_install_capacity(ioasid_t total);
+ioasid_t ioasid_get_capacity(void);
 ioasid_t ioasid_alloc(struct ioasid_set *set, ioasid_t min, ioasid_t max,
 		      void *private);
 void ioasid_free(ioasid_t ioasid);
@@ -42,6 +44,15 @@ void ioasid_unregister_allocator(struct ioasid_allocator_ops *allocator);
 int ioasid_attach_data(ioasid_t ioasid, void *data);
 void ioasid_detach_data(ioasid_t ioasid);
 #else /* !CONFIG_IOASID */
+static inline void ioasid_install_capacity(ioasid_t total)
+{
+}
+
+static inline ioasid_t ioasid_get_capacity(void)
+{
+	return 0;
+}
+
 static inline ioasid_t ioasid_alloc(struct ioasid_set *set, ioasid_t min,
 				    ioasid_t max, void *private)
 {
-- 
2.7.4