Re: [PATCH v3 3/3] iommu/amd: Remove ad-hoc checks that are never true

[Ankit Soni]

On Sun, Aug 23, 2026 at 06:20:17AM +0800, Rong Zhang wrote:
> The state transitions of the AMD IOMMU Initialization State Machine
> imply that some ad-hoc checks will never be true. In detail, they are
> only reachable if the previous state transitions have succeeded, but the
> conditions are only true if the previous state transitions have failed.
> 
> Therefore, remove the redundant ad-hoc checks.
> 
> Signed-off-by: Rong Zhang <i@xxxxxxxx>

Reviewed-by: Ankit Soni <Ankit.Soni@xxxxxxx>

> ---
>  drivers/iommu/amd/init.c | 13 +------------
>  1 file changed, 1 insertion(+), 12 deletions(-)
> 
> diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
> index 72b5b11b9d75..d81adb8efe0e 100644
> --- a/drivers/iommu/amd/init.c
> +++ b/drivers/iommu/amd/init.c
> @@ -163,7 +163,6 @@ int amd_iommu_gpt_level = PAGE_MODE_4_LEVEL;
>  int amd_iommu_guest_ir = AMD_IOMMU_GUEST_IR_VAPIC;
>  static int amd_iommu_xt_mode = IRQ_REMAP_XAPIC_MODE;
>  
> -static bool amd_iommu_detected;
>  static bool amd_iommu_disabled __initdata;
>  static bool amd_iommu_force_enable __initdata;
>  static bool amd_iommu_irtcachedis;
> @@ -3222,9 +3221,6 @@ static int __init early_amd_iommu_init(void)
>  	acpi_status status;
>  	u8 efr_hats, max_vasize;
>  
> -	if (!amd_iommu_detected)
> -		return -ENODEV;
> -
>  	status = acpi_get_table("IVRS", 0, &ivrs_base);
>  	if (status == AE_NOT_FOUND)
>  		return -ENODEV;
> @@ -3303,7 +3299,7 @@ static int __init early_amd_iommu_init(void)
>  	}
>  
>  	/* Disable any previously enabled IOMMUs */
> -	if (!is_kdump_kernel() || amd_iommu_disabled)
> +	if (!is_kdump_kernel())
>  		disable_iommus();
>  
>  	if (amd_iommu_irq_remap)
> @@ -3398,12 +3394,6 @@ static __init void iommu_snp_enable(void)
>  	if (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))
>  		return;
>  
> -	/* SNP support required IOMMU to be ON */
> -	if (no_iommu) {
> -		pr_warn("SNP: IOMMU disabled, SNP cannot be supported.\n");
> -		goto disable_snp;
> -	}
> -
>  	amd_iommu_snp_mode0_sup = check_feature2(FEATURE_SNP_PAGE_MODE0_SUP);
>  	/*
>  	 * If SNP page mode 0 is not enabled, then SNP support requires that IOMMU
> @@ -3716,7 +3706,6 @@ void __init amd_iommu_detect(void)
>  	if (ret)
>  		goto disable_snp;
>  
> -	amd_iommu_detected = true;
>  	iommu_detected = 1;
>  	x86_init.iommu.iommu_init = amd_iommu_init;
>  	return;
> 
> -- 
> 2.55.0
>