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>

5 files changed, 120 insertions, 1 deletions

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index ed92864d132..39fd3f42696 100644
--- a/arch/x86/Kconfig
+++ b/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
diff --git a/arch/x86/kernel/amd_iommu.c b/arch/x86/kernel/amd_iommu.c
index 15792ed082e..0e494b9d5f2 100644
--- a/arch/x86/kernel/amd_iommu.c
+++ b/arch/x86/kernel/amd_iommu.c
@@ -51,6 +51,17 @@ static int iommu_has_npcache(struct amd_iommu *iommu)
 
 /****************************************************************************
  *
+ * Interrupt handling functions
+ *
+ ****************************************************************************/
+
+irqreturn_t amd_iommu_int_handler(int irq, void *data)
+{
+        return IRQ_NONE;
+}
+
+/****************************************************************************
+ *
  * IOMMU command queuing functions
  *
  ****************************************************************************/
diff --git a/arch/x86/kernel/amd_iommu_init.c b/arch/x86/kernel/amd_iommu_init.c
index a7eb89d8923..14a06464a69 100644
--- a/arch/x86/kernel/amd_iommu_init.c
+++ b/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);
@@ -743,6 +750,95 @@ static int __init init_iommu_all(struct acpi_table_header *table)
 
 /****************************************************************************
  *
+ * 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
  * table. In this last pass the memory mapping requirements are
  * gathered (like exclusion and unity mapping reanges).
@@ -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);
         }
 }
diff --git a/include/asm-x86/amd_iommu.h b/include/asm-x86/amd_iommu.h
index 30a12049353..2fd97cb250c 100644
--- a/include/asm-x86/amd_iommu.h
+++ b/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) { }
diff --git a/include/asm-x86/amd_iommu_types.h b/include/asm-x86/amd_iommu_types.h
index a5629a21557..8533f09b34b 100644
--- a/include/asm-x86/amd_iommu_types.h
+++ b/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;
 };