[PATCH] iommu/amd: Enable Guest Translation after reading IOMMU feature register

[PATCH] iommu/amd: Enable Guest Translation after reading IOMMU feature register

[Vasant Hegde]

Commit 8e0179733172 ("iommu/amd: Enable Guest Translation before
registering devices") moved IOMMU Guest Translation (GT) enablement to
early init path. It does feature check based on Global EFR value (got from
ACPI IVRS table). Later it adjusts EFR value based on IOMMU feature
register (late_iommu_features_init()).

It seems in some systems BIOS doesn't set gloabl EFR value properly.
This is causing mismatch. Hence move IOMMU GT enablement after
late_iommu_features_init() so that it does check based on IOMMU EFR
value.

Link: https://lore.kernel.org/linux-iommu/333e6eb6-361c-4afb-8107-2573324bf689@gmail.com/
Fixes: 8e0179733172 ("iommu/amd: Enable Guest Translation before registering devices")
Reported-by: Klara Modin <klarasmodin@gmail.com>
Signed-off-by: Vasant Hegde <vasant.hegde@amd.com>
Tested-by: Klara Modin <klarasmodin@gmail.com>
---
 drivers/iommu/amd/init.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index fd3e76e43699..b292181995b7 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -2046,6 +2046,8 @@ static int __init iommu_init_pci(struct amd_iommu *iommu)
 			amd_iommu_max_glx_val = glxval;
 		else
 			amd_iommu_max_glx_val = min(amd_iommu_max_glx_val, glxval);
+
+		iommu_enable_gt(iommu);
 	}
 
 	if (check_feature(FEATURE_PPR) && amd_iommu_alloc_ppr_log(iommu))
@@ -2732,7 +2734,6 @@ static void early_enable_iommu(struct amd_iommu *iommu)
 	iommu_enable_command_buffer(iommu);
 	iommu_enable_event_buffer(iommu);
 	iommu_set_exclusion_range(iommu);
-	iommu_enable_gt(iommu);
 	iommu_enable_ga(iommu);
 	iommu_enable_xt(iommu);
 	iommu_enable_irtcachedis(iommu);
@@ -2789,7 +2790,6 @@ static void early_enable_iommus(void)
 			iommu_disable_irtcachedis(iommu);
 			iommu_enable_command_buffer(iommu);
 			iommu_enable_event_buffer(iommu);
-			iommu_enable_gt(iommu);
 			iommu_enable_ga(iommu);
 			iommu_enable_xt(iommu);
 			iommu_enable_irtcachedis(iommu);
-- 
2.31.1

Re: [PATCH] iommu/amd: Enable Guest Translation after reading IOMMU feature register

[Joerg Roedel]

On Mon, May 06, 2024 at 08:20:39AM +0000, Vasant Hegde wrote:
> Commit 8e0179733172 ("iommu/amd: Enable Guest Translation before
> registering devices") moved IOMMU Guest Translation (GT) enablement to
> early init path. It does feature check based on Global EFR value (got from
> ACPI IVRS table). Later it adjusts EFR value based on IOMMU feature
> register (late_iommu_features_init()).
> 
> It seems in some systems BIOS doesn't set gloabl EFR value properly.
> This is causing mismatch. Hence move IOMMU GT enablement after
> late_iommu_features_init() so that it does check based on IOMMU EFR
> value.
> 
> Link: https://lore.kernel.org/linux-iommu/333e6eb6-361c-4afb-8107-2573324bf689@gmail.com/
> Fixes: 8e0179733172 ("iommu/amd: Enable Guest Translation before registering devices")
> Reported-by: Klara Modin <klarasmodin@gmail.com>
> Signed-off-by: Vasant Hegde <vasant.hegde@amd.com>
> Tested-by: Klara Modin <klarasmodin@gmail.com>
> ---
>  drivers/iommu/amd/init.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

Wow, that was quick. Applied now, thanks!