AMD IOMMU: protect completion wait loop with iommu lock

The unlocked polling of the ComWaitInt bit in the IOMMU completion wait
path is racy. Protect it with the iommu lock.

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 a96d8c0..042fdc2 100644 (file)
--- a/arch/x86/kernel/amd_iommu.c
+++ b/arch/x86/kernel/amd_iommu.c
@@ -101,10 +101,10 @@ static int iommu_queue_command(struct amd_iommu *iommu, struct iommu_cmd *cmd)
  */
 static int iommu_completion_wait(struct amd_iommu *iommu)
 {
-       int ret, ready = 0;
+       int ret = 0, ready = 0;
        unsigned status = 0;
        struct iommu_cmd cmd;
-       unsigned long i = 0;
+       unsigned long flags, i = 0;
 
        memset(&cmd, 0, sizeof(cmd));
        cmd.data[0] = CMD_COMPL_WAIT_INT_MASK;
@@ -112,10 +112,12 @@ static int iommu_completion_wait(struct amd_iommu *iommu)
 
        iommu->need_sync = 0;
 
-       ret = iommu_queue_command(iommu, &cmd);
+       spin_lock_irqsave(&iommu->lock, flags);
+
+       ret = __iommu_queue_command(iommu, &cmd);
 
        if (ret)
-               return ret;
+               goto out;
 
        while (!ready && (i < EXIT_LOOP_COUNT)) {
                ++i;
@@ -130,6 +132,8 @@ static int iommu_completion_wait(struct amd_iommu *iommu)
 
        if (unlikely((i == EXIT_LOOP_COUNT) && printk_ratelimit()))
                printk(KERN_WARNING "AMD IOMMU: Completion wait loop failed\n");
+out:
+       spin_unlock_irqrestore(&iommu->lock, flags);
 
        return 0;
 }