AMD IOMMU: add MSI interrupt support

The AMD IOMMU can generate interrupts for various reasons. This patch
adds the basic interrupt enabling infrastructure to the driver.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/Kconfig

@@ -553,6 +553,7 @@ config CALGARY_IOMMU_ENABLED_BY_DEFAULT
 config AMD_IOMMU
 	bool "AMD IOMMU support"
 	select SWIOTLB
+	select PCI_MSI
 	depends on X86_64 && PCI && ACPI
 	help
 	  With this option you can enable support for AMD IOMMU hardware in

arch/x86/kernel/amd_iommu.c

@@ -49,6 +49,17 @@ static int iommu_has_npcache(struct amd_iommu *iommu)
 	return iommu->cap & IOMMU_CAP_NPCACHE;
 }
 
+/****************************************************************************
+ *
+ * Interrupt handling functions
+ *
+ ****************************************************************************/
+
+irqreturn_t amd_iommu_int_handler(int irq, void *data)
+{
+	return IRQ_NONE;
+}
+
 /****************************************************************************
  *
  * IOMMU command queuing functions

arch/x86/kernel/amd_iommu_init.c

@@ -22,6 +22,8 @@
 #include <linux/gfp.h>
 #include <linux/list.h>
 #include <linux/sysdev.h>
+#include <linux/interrupt.h>
+#include <linux/msi.h>
 #include <asm/pci-direct.h>
 #include <asm/amd_iommu_types.h>
 #include <asm/amd_iommu.h>
@@ -515,17 +517,20 @@ static void __init set_device_exclusion_range(u16 devid, struct ivmd_header *m)
 static void __init init_iommu_from_pci(struct amd_iommu *iommu)
 {
 	int cap_ptr = iommu->cap_ptr;
-	u32 range;
+	u32 range, misc;
 
 	pci_read_config_dword(iommu->dev, cap_ptr + MMIO_CAP_HDR_OFFSET,
 			      &iommu->cap);
 	pci_read_config_dword(iommu->dev, cap_ptr + MMIO_RANGE_OFFSET,
 			      &range);
+	pci_read_config_dword(iommu->dev, cap_ptr + MMIO_MISC_OFFSET,
+			      &misc);
 
 	iommu->first_device = calc_devid(MMIO_GET_BUS(range),
 					 MMIO_GET_FD(range));
 	iommu->last_device = calc_devid(MMIO_GET_BUS(range),
 					MMIO_GET_LD(range));
+	iommu->evt_msi_num = MMIO_MSI_NUM(misc);
 }
 
 /*
@@ -696,6 +701,8 @@ static int __init init_iommu_one(struct amd_iommu *iommu, struct ivhd_header *h)
 	if (!iommu->evt_buf)
 		return -ENOMEM;
 
+	iommu->int_enabled = false;
+
 	init_iommu_from_pci(iommu);
 	init_iommu_from_acpi(iommu, h);
 	init_iommu_devices(iommu);
@@ -741,6 +748,95 @@ static int __init init_iommu_all(struct acpi_table_header *table)
 	return 0;
 }
 
+/****************************************************************************
+ *
+ * The following functions initialize the MSI interrupts for all IOMMUs
+ * in the system. Its a bit challenging because there could be multiple
+ * IOMMUs per PCI BDF but we can call pci_enable_msi(x) only once per
+ * pci_dev.
+ *
+ ****************************************************************************/
+
+static int __init iommu_setup_msix(struct amd_iommu *iommu)
+{
+	struct amd_iommu *curr;
+	struct msix_entry entries[32]; /* only 32 supported by AMD IOMMU */
+	int nvec = 0, i;
+
+	list_for_each_entry(curr, &amd_iommu_list, list) {
+		if (curr->dev == iommu->dev) {
+			entries[nvec].entry = curr->evt_msi_num;
+			entries[nvec].vector = 0;
+			curr->int_enabled = true;
+			nvec++;
+		}
+	}
+
+	if (pci_enable_msix(iommu->dev, entries, nvec)) {
+		pci_disable_msix(iommu->dev);
+		return 1;
+	}
+
+	for (i = 0; i < nvec; ++i) {
+		int r = request_irq(entries->vector, amd_iommu_int_handler,
+				    IRQF_SAMPLE_RANDOM,
+				    "AMD IOMMU",
+				    NULL);
+		if (r)
+			goto out_free;
+	}
+
+	return 0;
+
+out_free:
+	for (i -= 1; i >= 0; --i)
+		free_irq(entries->vector, NULL);
+
+	pci_disable_msix(iommu->dev);
+
+	return 1;
+}
+
+static int __init iommu_setup_msi(struct amd_iommu *iommu)
+{
+	int r;
+	struct amd_iommu *curr;
+
+	list_for_each_entry(curr, &amd_iommu_list, list) {
+		if (curr->dev == iommu->dev)
+			curr->int_enabled = true;
+	}
+
+
+	if (pci_enable_msi(iommu->dev))
+		return 1;
+
+	r = request_irq(iommu->dev->irq, amd_iommu_int_handler,
+			IRQF_SAMPLE_RANDOM,
+			"AMD IOMMU",
+			NULL);
+
+	if (r) {
+		pci_disable_msi(iommu->dev);
+		return 1;
+	}
+
+	return 0;
+}
+
+static int __init iommu_init_msi(struct amd_iommu *iommu)
+{
+	if (iommu->int_enabled)
+		return 0;
+
+	if (pci_find_capability(iommu->dev, PCI_CAP_ID_MSIX))
+		return iommu_setup_msix(iommu);
+	else if (pci_find_capability(iommu->dev, PCI_CAP_ID_MSI))
+		return iommu_setup_msi(iommu);
+
+	return 1;
+}
+
 /****************************************************************************
  *
  * The next functions belong to the third pass of parsing the ACPI
@@ -862,6 +958,7 @@ static void __init enable_iommus(void)
 
 	list_for_each_entry(iommu, &amd_iommu_list, list) {
 		iommu_set_exclusion_range(iommu);
+		iommu_init_msi(iommu);
 		iommu_enable(iommu);
 	}
 }

include/asm-x86/amd_iommu.h

@@ -20,10 +20,13 @@
 #ifndef _ASM_X86_AMD_IOMMU_H
 #define _ASM_X86_AMD_IOMMU_H
 
+#include <linux/irqreturn.h>
+
 #ifdef CONFIG_AMD_IOMMU
 extern int amd_iommu_init(void);
 extern int amd_iommu_init_dma_ops(void);
 extern void amd_iommu_detect(void);
+extern irqreturn_t amd_iommu_int_handler(int irq, void *data);
 #else
 static inline int amd_iommu_init(void) { return -ENODEV; }
 static inline void amd_iommu_detect(void) { }

include/asm-x86/amd_iommu_types.h

@@ -37,6 +37,7 @@
 /* Capability offsets used by the driver */
 #define MMIO_CAP_HDR_OFFSET	0x00
 #define MMIO_RANGE_OFFSET	0x0c
+#define MMIO_MISC_OFFSET	0x10
 
 /* Masks, shifts and macros to parse the device range capability */
 #define MMIO_RANGE_LD_MASK	0xff000000
@@ -48,6 +49,7 @@
 #define MMIO_GET_LD(x)  (((x) & MMIO_RANGE_LD_MASK) >> MMIO_RANGE_LD_SHIFT)
 #define MMIO_GET_FD(x)  (((x) & MMIO_RANGE_FD_MASK) >> MMIO_RANGE_FD_SHIFT)
 #define MMIO_GET_BUS(x) (((x) & MMIO_RANGE_BUS_MASK) >> MMIO_RANGE_BUS_SHIFT)
+#define MMIO_MSI_NUM(x)	((x) & 0x1f)
 
 /* Flag masks for the AMD IOMMU exclusion range */
 #define MMIO_EXCL_ENABLE_MASK 0x01ULL
@@ -255,10 +257,15 @@ struct amd_iommu {
 	u8 *evt_buf;
 	/* size of event buffer */
 	u32 evt_buf_size;
+	/* MSI number for event interrupt */
+	u16 evt_msi_num;
 
 	/* if one, we need to send a completion wait command */
 	int need_sync;
 
+	/* true if interrupts for this IOMMU are already enabled */
+	bool int_enabled;
+
 	/* default dma_ops domain for that IOMMU */
 	struct dma_ops_domain *default_dom;
 };