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authorJoerg Roedel <jroedel@suse.de>2022-02-04 14:55:37 +0300
committerJoerg Roedel <jroedel@suse.de>2022-02-04 14:57:26 +0300
commit9b45a7738eec52bf0f5d8d3d54e822962781c5f2 (patch)
tree1fd8968308142638bdf4b4d5e35238471f01cafe
parent99e675d473eb8cf2deac1376a0f840222fc1adcf (diff)
downloadlinux-9b45a7738eec52bf0f5d8d3d54e822962781c5f2.tar.xz
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. Use a 10us for udelay(), has there is some hardware where activation of the GA log can take more than a 100ms. A future optimization should move the activation check of the GA log to the point where it gets used for the first time. But that is a bigger change and not suitable for a fix. Fixes: 8bda0cfbdc1a ("iommu/amd: Detect and initialize guest vAPIC log") Signed-off-by: Joerg Roedel <jroedel@suse.de> Link: https://lore.kernel.org/r/20220204115537.3894-1-joro@8bytes.org
-rw-r--r--drivers/iommu/amd/init.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index dc338acf3338..b10fb52ea442 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -21,6 +21,7 @@
#include <linux/export.h>
#include <linux/kmemleak.h>
#include <linux/cc_platform.h>
+#include <linux/iopoll.h>
#include <asm/pci-direct.h>
#include <asm/iommu.h>
#include <asm/apic.h>
@@ -834,6 +835,7 @@ 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(10);
}
if (WARN_ON(i >= LOOP_TIMEOUT))