Re: [PATCH v3 2/2] iommu/amd: Adhere to IVINFO[VASIZE] for address limits

[Vasant Hegde <vasant.hegde@amd.com>]

On 3/9/2026 7:35 PM, Ankit Soni wrote:
> ACPI IVRS IVHD’s IVINFO field reports the maximum virtual address
> size (VASIZE) supported by the IOMMU. The AMD IOMMU driver currently
> caps this with pagetable level reported by EFR[HATS] when configuring
> paging domains (hw_max_vasz_lg2). On systems where firmware or VM
> advertises smaller or different limits, the driver may over-advertise
> capabilities and create domains outside the hardware’s actual bounds.


> 
> Signed-off-by: Ankit Soni <Ankit.Soni@amd.com>

Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>

-Vasant

> ---
>  drivers/iommu/amd/amd_iommu.h       |  2 +-
>  drivers/iommu/amd/amd_iommu_types.h |  1 +
>  drivers/iommu/amd/init.c            | 13 +++++++++----
>  drivers/iommu/amd/iommu.c           |  3 +--
>  4 files changed, 12 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/iommu/amd/amd_iommu.h b/drivers/iommu/amd/amd_iommu.h
> index 1342e764a548..f915938a3a08 100644
> --- a/drivers/iommu/amd/amd_iommu.h
> +++ b/drivers/iommu/amd/amd_iommu.h
> @@ -41,7 +41,7 @@ int amd_iommu_enable_faulting(unsigned int cpu);
>  extern int amd_iommu_guest_ir;
>  extern enum protection_domain_mode amd_iommu_pgtable;
>  extern int amd_iommu_gpt_level;
> -extern u8 amd_iommu_hpt_level;
> +extern u8 amd_iommu_hpt_vasize;
>  extern unsigned long amd_iommu_pgsize_bitmap;
>  extern bool amd_iommu_hatdis;
>  
> diff --git a/drivers/iommu/amd/amd_iommu_types.h b/drivers/iommu/amd/amd_iommu_types.h
> index c685d3771436..6a85a38d34bd 100644
> --- a/drivers/iommu/amd/amd_iommu_types.h
> +++ b/drivers/iommu/amd/amd_iommu_types.h
> @@ -395,6 +395,7 @@
>  #define IOMMU_IVINFO_OFFSET     36
>  #define IOMMU_IVINFO_EFRSUP     BIT(0)
>  #define IOMMU_IVINFO_DMA_REMAP  BIT(1)
> +#define IOMMU_IVINFO_VASIZE	GENMASK_ULL(21, 15)
>  
>  /* IOMMU Feature Reporting Field (for IVHD type 10h */
>  #define IOMMU_FEAT_GASUP_SHIFT	6
> diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
> index f3fd7f39efb4..e874a4135d5c 100644
> --- a/drivers/iommu/amd/init.c
> +++ b/drivers/iommu/amd/init.c
> @@ -152,8 +152,8 @@ bool amd_iommu_dump;
>  bool amd_iommu_irq_remap __read_mostly;
>  
>  enum protection_domain_mode amd_iommu_pgtable = PD_MODE_V1;
> -/* Host page table level */
> -u8 amd_iommu_hpt_level;
> +/* Virtual address size */
> +u8 amd_iommu_hpt_vasize;
>  /* Guest page table level */
>  int amd_iommu_gpt_level = PAGE_MODE_4_LEVEL;
>  
> @@ -3188,7 +3188,7 @@ static int __init early_amd_iommu_init(void)
>  	struct acpi_table_header *ivrs_base;
>  	int ret;
>  	acpi_status status;
> -	u8 efr_hats;
> +	u8 efr_hats, max_vasize;
>  
>  	if (!amd_iommu_detected)
>  		return -ENODEV;
> @@ -3218,6 +3218,10 @@ static int __init early_amd_iommu_init(void)
>  
>  	ivinfo_init(ivrs_base);
>  
> +	max_vasize = FIELD_GET(IOMMU_IVINFO_VASIZE, amd_iommu_ivinfo);
> +	if (!max_vasize)
> +		max_vasize = 64;
> +
>  	amd_iommu_target_ivhd_type = get_highest_supported_ivhd_type(ivrs_base);
>  	DUMP_printk("Using IVHD type %#x\n", amd_iommu_target_ivhd_type);
>  
> @@ -3240,7 +3244,8 @@ static int __init early_amd_iommu_init(void)
>  		 * efr[HATS] bits specify the maximum host translation level
>  		 * supported, with LEVEL 4 being initial max level.
>  		 */
> -		amd_iommu_hpt_level = efr_hats + PAGE_MODE_4_LEVEL;
> +		amd_iommu_hpt_vasize = min_t(unsigned int, max_vasize,
> +					 (efr_hats + PAGE_MODE_4_LEVEL - 1) * 9 + 21);
>  	} else {
>  		pr_warn_once(FW_BUG "Disable host address translation due to invalid translation level (%#x).\n",
>  			     efr_hats);
> diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
> index 81c4d7733872..e8d15ac9b2bd 100644
> --- a/drivers/iommu/amd/iommu.c
> +++ b/drivers/iommu/amd/iommu.c
> @@ -2712,8 +2712,7 @@ static struct iommu_domain *amd_iommu_domain_alloc_paging_v1(struct device *dev,
>  	else
>  		cfg.common.features |= BIT(PT_FEAT_FLUSH_RANGE);
>  
> -	cfg.common.hw_max_vasz_lg2 =
> -		min(64, (amd_iommu_hpt_level - 1) * 9 + 21);
> +	cfg.common.hw_max_vasz_lg2 = amd_iommu_hpt_vasize;
>  	cfg.common.hw_max_oasz_lg2 = 52;
>  	cfg.starting_level = 2;
>  	domain->domain.ops = &amdv1_ops;