iommu/amd: Fix loop timeout issue in iommu_ga_log_enable()

The polling loop for the register change in iommu_ga_log_enable() needs
to have a udelay() in it.  Otherwise the CPU might be faster than the
IOMMU hardware and wrongly trigger the WARN_ON() further down the code
stream.

Fixes: 8bda0cf ("iommu/amd: Detect and initialize guest vAPIC log")
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/amd/init.c

@@ -834,6 +834,7 @@ static int iommu_ga_log_enable(struct amd_iommu *iommu)
 		status = readl(iommu->mmio_base + MMIO_STATUS_OFFSET);
 		if (status & (MMIO_STATUS_GALOG_RUN_MASK))
 			break;
+		udelay(1);
 	}
 
 	if (WARN_ON(i >= LOOP_TIMEOUT))