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From:   Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
To:     <linux-kernel@vger.kernel.org>, <iommu@lists.linux.dev>,
        <joro@8bytes.org>, <jgg@nvidia.com>
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        <pandoh@google.com>, <loganodell@google.com>,
        Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Subject: [RFC PATCH 3/6] iommu/amd: Introduce Guest-ID struct amd_iommu_vminfo
Date:   Tue, 12 Dec 2023 10:01:36 -0600
Message-ID: <20231212160139.174229-4-suravee.suthikulpanit@amd.com>
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AMD HW-vIOMMU feature requires IOMMU driver to specify a unique 16-bit
Guest ID (GID) for each VM. This ID is used to index into various
data structures for configuring the hardware.

Introduce amd_iommu_vminfo_hash hashtable to store per-vm configuration,
which uses 16-bit GID as a hash key along with helper functions.

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
---
 drivers/iommu/amd/amd_iommu.h       |  6 +++
 drivers/iommu/amd/amd_iommu_types.h |  6 +++
 drivers/iommu/amd/iommu.c           | 66 +++++++++++++++++++++++++++++
 3 files changed, 78 insertions(+)

diff --git a/drivers/iommu/amd/amd_iommu.h b/drivers/iommu/amd/amd_iommu.h
index 4118129f4a24..7783a933ad14 100644
--- a/drivers/iommu/amd/amd_iommu.h
+++ b/drivers/iommu/amd/amd_iommu.h
@@ -182,4 +182,10 @@ void amd_iommu_domain_set_pgtable(struct protection_domain *domain,
 struct dev_table_entry *get_dev_table(struct amd_iommu *iommu);
 
 extern bool amd_iommu_snp_en;
+
+/* AMD IOMMU GID */
+int amd_iommu_vminfo_alloc(struct amd_iommu *iommu, struct amd_iommu_vminfo *vminfo);
+void amd_iommu_vminfo_free(struct amd_iommu *iommu, struct amd_iommu_vminfo *vminfo);
+struct amd_iommu_vminfo *amd_iommu_get_vminfo(int gid);
+
 #endif
diff --git a/drivers/iommu/amd/amd_iommu_types.h b/drivers/iommu/amd/amd_iommu_types.h
index 956fd4658a4a..a00731673c50 100644
--- a/drivers/iommu/amd/amd_iommu_types.h
+++ b/drivers/iommu/amd/amd_iommu_types.h
@@ -16,6 +16,7 @@
 #include <linux/pci.h>
 #include <linux/irqreturn.h>
 #include <linux/io-pgtable.h>
+#include <linux/hashtable.h>
 
 /*
  * Maximum number of IOMMUs supported
@@ -1053,6 +1054,11 @@ struct amd_irte_ops {
 	void (*clear_allocated)(struct irq_remap_table *, int);
 };
 
+struct amd_iommu_vminfo {
+	u16 gid;
+	struct hlist_node hnode;
+};
+
 #ifdef CONFIG_IRQ_REMAP
 extern struct amd_irte_ops irte_32_ops;
 extern struct amd_irte_ops irte_128_ops;
diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index c41932e9f16a..d18b23ac6357 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -23,6 +23,7 @@
 #include <linux/amd-iommu.h>
 #include <linux/notifier.h>
 #include <linux/export.h>
+#include <linux/idr.h>
 #include <linux/irq.h>
 #include <linux/msi.h>
 #include <linux/irqdomain.h>
@@ -66,6 +67,16 @@ LIST_HEAD(acpihid_map);
 const struct iommu_ops amd_iommu_ops;
 static const struct iommu_dirty_ops amd_dirty_ops;
 
+/* VMInfo Hashtable */
+#define AMD_IOMMU_VMINFO_HASH_BITS	16
+DEFINE_HASHTABLE(amd_iommu_vminfo_hash, AMD_IOMMU_VMINFO_HASH_BITS);
+DEFINE_SPINLOCK(amd_iommu_vminfo_hash_lock);
+
+/* Global VMID */
+#define AMD_IOMMU_VMID_INVALID (-1U)
+static DEFINE_IDA(amd_iommu_global_vmid_ida);
+static u32 amd_iommu_latest_gid;
+
 int amd_iommu_max_glx_val = -1;
 
 /*
@@ -101,6 +112,61 @@ static inline bool domain_id_is_per_dev(struct protection_domain *pdom)
 	return (pdom && pdom->pd_mode != PD_MODE_V1);
 }
 
+int get_vmid(void)
+{
+	int ret;
+
+	ret = ida_alloc_range(&amd_iommu_global_vmid_ida, 1, 0xFFFF, GFP_KERNEL);
+	return ret < 0 ? AMD_IOMMU_VMID_INVALID : ret;
+}
+
+int amd_iommu_vminfo_alloc(struct amd_iommu *iommu, struct amd_iommu_vminfo *vminfo)
+{
+	u32 gid;
+	unsigned long flags;
+
+	spin_lock_irqsave(&amd_iommu_vminfo_hash_lock, flags);
+	gid = amd_iommu_latest_gid = get_vmid();
+	if (gid == AMD_IOMMU_VMID_INVALID)
+		return -EINVAL;
+
+	pr_debug("%s: gid=%u\n", __func__, gid);
+	vminfo->gid = gid;
+	hash_add(amd_iommu_vminfo_hash, &vminfo->hnode, vminfo->gid);
+	spin_unlock_irqrestore(&amd_iommu_vminfo_hash_lock, flags);
+	return 0;
+}
+
+void amd_iommu_vminfo_free(struct amd_iommu *iommu,
+			    struct amd_iommu_vminfo *vminfo)
+{
+	unsigned long flags;
+
+	pr_debug("%s: gid=%u\n", __func__, vminfo->gid);
+	spin_lock_irqsave(&amd_iommu_vminfo_hash_lock, flags);
+	hash_del(&vminfo->hnode);
+	ida_free(&amd_iommu_global_vmid_ida, vminfo->gid);
+	spin_unlock_irqrestore(&amd_iommu_vminfo_hash_lock, flags);
+}
+
+struct amd_iommu_vminfo *amd_iommu_get_vminfo(int gid)
+{
+	unsigned long flags;
+	struct amd_iommu_vminfo *tmp, *ptr = NULL;
+
+	spin_lock_irqsave(&amd_iommu_vminfo_hash_lock, flags);
+	hash_for_each_possible(amd_iommu_vminfo_hash, tmp, hnode, gid) {
+		if (tmp->gid == gid) {
+			ptr = tmp;
+			break;
+		}
+	}
+	if (!ptr)
+		pr_debug("%s : gid=%u not found\n", __func__, gid);
+	spin_unlock_irqrestore(&amd_iommu_vminfo_hash_lock, flags);
+	return ptr;
+}
+
 static inline int get_acpihid_device_id(struct device *dev,
 					struct acpihid_map_entry **entry)
 {
-- 
2.34.1