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| author | Joerg Roedel <jroedel@suse.de> | 2022-02-04 12:55:37 +0100 |
|---|---|---|
| committer | Joerg Roedel <jroedel@suse.de> | 2022-02-04 12:57:26 +0100 |
| commit | 9b45a7738eec52bf0f5d8d3d54e822962781c5f2 (patch) | |
| tree | 1fd8968308142638bdf4b4d5e35238471f01cafe | |
| parent | 99e675d473eb8cf2deac1376a0f840222fc1adcf (diff) | |
| download | linux-dm-9b45a7738eec52bf0f5d8d3d54e822962781c5f2.tar.gz | |
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.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c index dc338acf33385b..b10fb52ea44288 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)) |