| From 9b45a7738eec52bf0f5d8d3d54e822962781c5f2 Mon Sep 17 00:00:00 2001 |
| From: Joerg Roedel <jroedel@suse.de> |
| Date: Fri, 4 Feb 2022 12:55:37 +0100 |
| Subject: iommu/amd: Fix loop timeout issue in iommu_ga_log_enable() |
| |
| From: Joerg Roedel <jroedel@suse.de> |
| |
| 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> |
| --- |
| drivers/iommu/amd/init.c | 2 ++ |
| 1 file changed, 2 insertions(+) |
| |
| --- a/drivers/iommu/amd/init.c |
| +++ b/drivers/iommu/amd/init.c |
| @@ -20,6 +20,7 @@ |
| #include <linux/export.h> |
| #include <linux/kmemleak.h> |
| #include <linux/mem_encrypt.h> |
| +#include <linux/iopoll.h> |
| #include <asm/pci-direct.h> |
| #include <asm/iommu.h> |
| #include <asm/apic.h> |
| @@ -833,6 +834,7 @@ static int iommu_ga_log_enable(struct am |
| status = readl(iommu->mmio_base + MMIO_STATUS_OFFSET); |
| if (status & (MMIO_STATUS_GALOG_RUN_MASK)) |
| break; |
| + udelay(10); |
| } |
| |
| if (WARN_ON(i >= LOOP_TIMEOUT)) |