AMD IOMMU: add event buffer allocation

This patch adds the allocation of a event buffer for each AMD IOMMU in
the system. The hardware will log events like device page faults or
other errors to this buffer once this is enabled.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/amd_iommu_init.c

@@ -417,6 +417,30 @@ static void __init free_command_buffer(struct amd_iommu *iommu)
 	free_pages((unsigned long)iommu->cmd_buf, get_order(CMD_BUFFER_SIZE));
 }
 
+/* allocates the memory where the IOMMU will log its events to */
+static u8 * __init alloc_event_buffer(struct amd_iommu *iommu)
+{
+	u64 entry;
+	iommu->evt_buf = (u8 *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
+						get_order(EVT_BUFFER_SIZE));
+
+	if (iommu->evt_buf == NULL)
+		return NULL;
+
+	entry = (u64)virt_to_phys(iommu->evt_buf) | EVT_LEN_MASK;
+	memcpy_toio(iommu->mmio_base + MMIO_EVT_BUF_OFFSET,
+		    &entry, sizeof(entry));
+
+	iommu->evt_buf_size = EVT_BUFFER_SIZE;
+
+	return iommu->evt_buf;
+}
+
+static void __init free_event_buffer(struct amd_iommu *iommu)
+{
+	free_pages((unsigned long)iommu->evt_buf, get_order(EVT_BUFFER_SIZE));
+}
+
 /* sets a specific bit in the device table entry. */
 static void set_dev_entry_bit(u16 devid, u8 bit)
 {
@@ -622,6 +646,7 @@ static int __init init_iommu_devices(struct amd_iommu *iommu)
 static void __init free_iommu_one(struct amd_iommu *iommu)
 {
 	free_command_buffer(iommu);
+	free_event_buffer(iommu);
 	iommu_unmap_mmio_space(iommu);
 }
 
@@ -661,6 +686,10 @@ static int __init init_iommu_one(struct amd_iommu *iommu, struct ivhd_header *h)
 	if (!iommu->cmd_buf)
 		return -ENOMEM;
 
+	iommu->evt_buf = alloc_event_buffer(iommu);
+	if (!iommu->evt_buf)
+		return -ENOMEM;
+
 	init_iommu_from_pci(iommu);
 	init_iommu_from_acpi(iommu, h);
 	init_iommu_devices(iommu);

include/asm-x86/amd_iommu_types.h

@@ -116,6 +116,10 @@
 #define MMIO_CMD_SIZE_SHIFT 56
 #define MMIO_CMD_SIZE_512 (0x9ULL << MMIO_CMD_SIZE_SHIFT)
 
+/* constants for event buffer handling */
+#define EVT_BUFFER_SIZE		8192 /* 512 entries */
+#define EVT_LEN_MASK		(0x9ULL << 56)
+
 #define PAGE_MODE_1_LEVEL 0x01
 #define PAGE_MODE_2_LEVEL 0x02
 #define PAGE_MODE_3_LEVEL 0x03
@@ -243,6 +247,11 @@ struct amd_iommu {
 	/* size of command buffer */
 	u32 cmd_buf_size;
 
+	/* event buffer virtual address */
+	u8 *evt_buf;
+	/* size of event buffer */
+	u32 evt_buf_size;
+
 	/* if one, we need to send a completion wait command */
 	int need_sync;