[PATCH] iommu/amd: Add support for X2APIC IOMMU interrupts

[Suthikulpanit, Suravee]

AMD IOMMU requires IntCapXT registers to be setup in order to generate
its own interrupts (for Event Log, PPR Log, and GA Log) with 32-bit
APIC destination ID. Without this support, AMD IOMMU MSI interrupts
will not be routed correctly when booting the system in X2APIC mode.

Cc: Joerg Roedel <joro@xxxxxxxxxx>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>
---
 drivers/iommu/amd_iommu_init.c  | 90 +++++++++++++++++++++++++++++++++++++++++
 drivers/iommu/amd_iommu_types.h |  9 +++++
 2 files changed, 99 insertions(+)

diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
index ff40ba7..a4c5b1e 100644
--- a/drivers/iommu/amd_iommu_init.c
+++ b/drivers/iommu/amd_iommu_init.c
@@ -35,6 +35,8 @@
 #include <linux/mem_encrypt.h>
 #include <asm/pci-direct.h>
 #include <asm/iommu.h>
+#include <asm/apic.h>
+#include <asm/msidef.h>
 #include <asm/gart.h>
 #include <asm/x86_init.h>
 #include <asm/iommu_table.h>
@@ -1935,6 +1937,90 @@ static int iommu_setup_msi(struct amd_iommu *iommu)
 	return 0;
 }
 
+#define XT_INT_DEST_MODE(x)	(((x) & 0x1ULL) << 2)
+#define XT_INT_DEST_LO(x)	(((x) & 0xFFFFFFULL) << 8)
+#define XT_INT_VEC(x)		(((x) & 0xFFULL) << 32)
+#define XT_INT_DEST_HI(x)	((((x) >> 24) & 0xFFULL) << 56)
+
+/**
+ * Setup the IntCapXT registers with interrupt routing information
+ * based on the PCI MSI capability block registers, accessed via
+ * MMIO MSI address low/hi and MSI data registers.
+ */
+static void iommu_update_intcapxt(struct amd_iommu *iommu)
+{
+	u64 val;
+	u32 addr_lo = readl(iommu->mmio_base + MMIO_MSI_ADDR_LO_OFFSET);
+	u32 addr_hi = readl(iommu->mmio_base + MMIO_MSI_ADDR_HI_OFFSET);
+	u32 data    = readl(iommu->mmio_base + MMIO_MSI_DATA_OFFSET);
+	bool dm     = (addr_lo >> MSI_ADDR_DEST_MODE_SHIFT) & 0x1;
+	u32 dest    = ((addr_lo >> MSI_ADDR_DEST_ID_SHIFT) & 0xFF);
+
+	if (x2apic_enabled())
+		dest |= MSI_ADDR_EXT_DEST_ID(addr_hi);
+
+	val = XT_INT_VEC(data & 0xFF) |
+	      XT_INT_DEST_MODE(dm) |
+	      XT_INT_DEST_LO(dest) |
+	      XT_INT_DEST_HI(dest);
+
+	/**
+	 * Current IOMMU implemtation uses the same IRQ for all
+	 * 3 IOMMU interrupts.
+	 */
+	writeq(val, iommu->mmio_base + MMIO_INTCAPXT_EVT_OFFSET);
+	writeq(val, iommu->mmio_base + MMIO_INTCAPXT_PPR_OFFSET);
+	writeq(val, iommu->mmio_base + MMIO_INTCAPXT_GALOG_OFFSET);
+}
+
+static void _irq_notifier_notify(struct irq_affinity_notify *notify,
+				 const cpumask_t *mask)
+{
+	struct amd_iommu *iommu;
+
+	for_each_iommu(iommu) {
+		if (iommu->dev->irq == notify->irq) {
+			iommu_update_intcapxt(iommu);
+			break;
+		}
+	}
+}
+
+static void _irq_notifier_release(struct kref *ref)
+{
+}
+
+static int iommu_init_intcapxt(struct amd_iommu *iommu)
+{
+	int ret;
+	struct irq_affinity_notify *notify = &iommu->intcapxt_notify;
+
+	/**
+	 * IntCapXT requires XTSup=1, which can be inferred
+	 * amd_iommu_xt_mode.
+	 */
+	if (amd_iommu_xt_mode != IRQ_REMAP_X2APIC_MODE)
+		return 0;
+
+	/**
+	 * Also, we need to setup notifier to update the IntCapXT registers
+	 * whenever the irq affinity is changed from user-space.
+	 */
+	notify->irq = iommu->dev->irq;
+	notify->notify = _irq_notifier_notify,
+	notify->release = _irq_notifier_release,
+	ret = irq_set_affinity_notifier(iommu->dev->irq, notify);
+	if (ret) {
+		pr_err("Failed to register irq affinity notifier (devid=%#x, irq %d)\n",
+		       iommu->devid, iommu->dev->irq);
+		return ret;
+	}
+
+	iommu_update_intcapxt(iommu);
+	iommu_feature_enable(iommu, CONTROL_INTCAPXT_EN);
+	return ret;
+}
+
 static int iommu_init_msi(struct amd_iommu *iommu)
 {
 	int ret;
@@ -1951,6 +2037,10 @@ static int iommu_init_msi(struct amd_iommu *iommu)
 		return ret;
 
 enable_faults:
+	ret = iommu_init_intcapxt(iommu);
+	if (ret)
+		return ret;
+
 	iommu_feature_enable(iommu, CONTROL_EVT_INT_EN);
 
 	if (iommu->ppr_log != NULL)
diff --git a/drivers/iommu/amd_iommu_types.h b/drivers/iommu/amd_iommu_types.h
index 87965e4..39be804f 100644
--- a/drivers/iommu/amd_iommu_types.h
+++ b/drivers/iommu/amd_iommu_types.h
@@ -72,6 +72,12 @@
 #define MMIO_PPR_LOG_OFFSET	0x0038
 #define MMIO_GA_LOG_BASE_OFFSET	0x00e0
 #define MMIO_GA_LOG_TAIL_OFFSET	0x00e8
+#define MMIO_MSI_ADDR_LO_OFFSET	0x015C
+#define MMIO_MSI_ADDR_HI_OFFSET	0x0160
+#define MMIO_MSI_DATA_OFFSET	0x0164
+#define MMIO_INTCAPXT_EVT_OFFSET	0x0170
+#define MMIO_INTCAPXT_PPR_OFFSET	0x0178
+#define MMIO_INTCAPXT_GALOG_OFFSET	0x0180
 #define MMIO_CMD_HEAD_OFFSET	0x2000
 #define MMIO_CMD_TAIL_OFFSET	0x2008
 #define MMIO_EVT_HEAD_OFFSET	0x2010
@@ -162,6 +168,7 @@
 #define CONTROL_GALOG_EN        0x1CULL
 #define CONTROL_GAINT_EN        0x1DULL
 #define CONTROL_XT_EN           0x32ULL
+#define CONTROL_INTCAPXT_EN     0x33ULL
 
 #define CTRL_INV_TO_MASK	(7 << CONTROL_INV_TIMEOUT)
 #define CTRL_INV_TO_NONE	0
@@ -604,6 +611,8 @@ struct amd_iommu {
 	/* DebugFS Info */
 	struct dentry *debugfs;
 #endif
+	/* IRQ notifier for IntCapXT interrupt */
+	struct irq_affinity_notify intcapxt_notify;
 };
 
 static inline struct amd_iommu *dev_to_amd_iommu(struct device *dev)
-- 
1.8.3.1