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x86, AMD IOMMU: use status bit instead of memory write-back for completion wait 

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Joerg Roedel 2008-08-14 19:55:15 +02:00 committed by Ingo Molnar
parent b635acec48
commit 519c31bacf
2 changed files with 14 additions and 7 deletions
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17
arch/x86/kernel/amd_iommu.c
View File

@ -101,16 +101,13 @@ static int iommu_queue_command(struct amd_iommu *iommu, struct iommu_cmd *cmd)
*/ */
static int iommu_completion_wait(struct amd_iommu *iommu) static int iommu_completion_wait(struct amd_iommu *iommu)
{ {
int ret; int ret, ready = 0;
unsigned status = 0;
struct iommu_cmd cmd; struct iommu_cmd cmd;
volatile u64 ready = 0;
unsigned long ready_phys = virt_to_phys(&ready);
unsigned long i = 0; unsigned long i = 0;
memset(&cmd, 0, sizeof(cmd)); memset(&cmd, 0, sizeof(cmd));
cmd.data[0] = LOW_U32(ready_phys) | CMD_COMPL_WAIT_STORE_MASK; cmd.data[0] = CMD_COMPL_WAIT_INT_MASK;
cmd.data[1] = upper_32_bits(ready_phys);
cmd.data[2] = 1; /* value written to 'ready' */
CMD_SET_TYPE(&cmd, CMD_COMPL_WAIT); CMD_SET_TYPE(&cmd, CMD_COMPL_WAIT);
iommu->need_sync = 0; iommu->need_sync = 0;
@ -122,9 +119,15 @@ static int iommu_completion_wait(struct amd_iommu *iommu)
while (!ready && (i < EXIT_LOOP_COUNT)) { while (!ready && (i < EXIT_LOOP_COUNT)) {
++i; ++i;
cpu_relax(); /* wait for the bit to become one */
status = readl(iommu->mmio_base + MMIO_STATUS_OFFSET);
ready = status & MMIO_STATUS_COM_WAIT_INT_MASK;
} }
/* set bit back to zero */
status &= ~MMIO_STATUS_COM_WAIT_INT_MASK;
writel(status, iommu->mmio_base + MMIO_STATUS_OFFSET);
if (unlikely((i == EXIT_LOOP_COUNT) && printk_ratelimit())) if (unlikely((i == EXIT_LOOP_COUNT) && printk_ratelimit()))
printk(KERN_WARNING "AMD IOMMU: Completion wait loop failed\n"); printk(KERN_WARNING "AMD IOMMU: Completion wait loop failed\n");

4
include/asm-x86/amd_iommu_types.h
View File

@ -69,6 +69,9 @@
#define MMIO_EVT_TAIL_OFFSET 0x2018 #define MMIO_EVT_TAIL_OFFSET 0x2018
#define MMIO_STATUS_OFFSET 0x2020 #define MMIO_STATUS_OFFSET 0x2020
/* MMIO status bits */
#define MMIO_STATUS_COM_WAIT_INT_MASK 0x04
/* feature control bits */ /* feature control bits */
#define CONTROL_IOMMU_EN 0x00ULL #define CONTROL_IOMMU_EN 0x00ULL
#define CONTROL_HT_TUN_EN 0x01ULL #define CONTROL_HT_TUN_EN 0x01ULL
@ -89,6 +92,7 @@
#define CMD_INV_IOMMU_PAGES 0x03 #define CMD_INV_IOMMU_PAGES 0x03
#define CMD_COMPL_WAIT_STORE_MASK 0x01 #define CMD_COMPL_WAIT_STORE_MASK 0x01
#define CMD_COMPL_WAIT_INT_MASK 0x02
#define CMD_INV_IOMMU_PAGES_SIZE_MASK 0x01 #define CMD_INV_IOMMU_PAGES_SIZE_MASK 0x01
#define CMD_INV_IOMMU_PAGES_PDE_MASK 0x02 #define CMD_INV_IOMMU_PAGES_PDE_MASK 0x02