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| author | Joerg Roedel <jroedel@suse.de> | 2022-02-04 12:55:37 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-02-08 18:15:29 +0100 |
| commit | 90e970cfd682d40cbc5a5c39ee5889048541c1a6 (patch) | |
| tree | 4465b424f68dc972fb0df9e3864f27a3a6434cd2 | |
| parent | d4b746e60fd8eaa8016e144223abe91158edcdad (diff) | |
| download | linux-90e970cfd682d40cbc5a5c39ee5889048541c1a6.tar.gz linux-90e970cfd682d40cbc5a5c39ee5889048541c1a6.tar.bz2 linux-90e970cfd682d40cbc5a5c39ee5889048541c1a6.zip | |
iommu/amd: Fix loop timeout issue in iommu_ga_log_enable()
commit 9b45a7738eec52bf0f5d8d3d54e822962781c5f2 upstream.
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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/iommu/amd_iommu_init.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c index a3279f303b49..45c809f3d24f 100644 --- a/drivers/iommu/amd_iommu_init.c +++ b/drivers/iommu/amd_iommu_init.c @@ -28,6 +28,7 @@ #include <linux/amd-iommu.h> #include <linux/export.h> #include <linux/iommu.h> +#include <linux/iopoll.h> #include <asm/pci-direct.h> #include <asm/iommu.h> #include <asm/gart.h> @@ -715,6 +716,7 @@ 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 (i >= LOOP_TIMEOUT) |