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>
diff --git a/arch/x86/kernel/amd_iommu.c b/arch/x86/kernel/amd_iommu.c
index 22d7d05..028e945 100644
--- a/arch/x86/kernel/amd_iommu.c
+++ b/arch/x86/kernel/amd_iommu.c
@@ -101,16 +101,13 @@
*/
static int iommu_completion_wait(struct amd_iommu *iommu)
{
- int ret;
+ int ret, ready = 0;
+ unsigned status = 0;
struct iommu_cmd cmd;
- volatile u64 ready = 0;
- unsigned long ready_phys = virt_to_phys(&ready);
unsigned long i = 0;
memset(&cmd, 0, sizeof(cmd));
- cmd.data[0] = LOW_U32(ready_phys) | CMD_COMPL_WAIT_STORE_MASK;
- cmd.data[1] = upper_32_bits(ready_phys);
- cmd.data[2] = 1; /* value written to 'ready' */
+ cmd.data[0] = CMD_COMPL_WAIT_INT_MASK;
CMD_SET_TYPE(&cmd, CMD_COMPL_WAIT);
iommu->need_sync = 0;
@@ -122,9 +119,15 @@
while (!ready && (i < EXIT_LOOP_COUNT)) {
++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()))
printk(KERN_WARNING "AMD IOMMU: Completion wait loop failed\n");