Re: [RFC v2 03/22] intel_iommu: modify x-scalable-mode to be string option

[Peter Xu]

On Thu, Oct 24, 2019 at 08:34:24AM -0400, Liu Yi L wrote:
> Intel VT-d 3.0 introduces scalable mode, and it has a bunch of capabilities
> related to scalable mode translation, thus there are multiple combinations.
> While this vIOMMU implementation wants simplify it for user by providing
> typical combinations. User could config it by "x-scalable-mode" option. The
> usage is as below:
> 
> "-device intel-iommu,x-scalable-mode=["legacy"|"modern"]"
> 
>  - "legacy": gives support for SL page table
>  - "modern": gives support for FL page table, pasid, virtual command
>  -  if not configured, means no scalable mode support, if not proper
>     configured, will throw error
> 
> Cc: Kevin Tian <address@hidden>
> Cc: Jacob Pan <address@hidden>
> Cc: Peter Xu <address@hidden>
> Cc: Yi Sun <address@hidden>
> Signed-off-by: Liu Yi L <address@hidden>
> Signed-off-by: Yi Sun <address@hidden>
> ---
>  hw/i386/intel_iommu.c          | 15 +++++++++++++--
>  hw/i386/intel_iommu_internal.h |  3 +++
>  include/hw/i386/intel_iommu.h  |  2 +-
>  3 files changed, 17 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
> index 771bed2..4a1a07a 100644
> --- a/hw/i386/intel_iommu.c
> +++ b/hw/i386/intel_iommu.c
> @@ -3019,7 +3019,7 @@ static Property vtd_properties[] = {
>      DEFINE_PROP_UINT8("aw-bits", IntelIOMMUState, aw_bits,
>                        VTD_HOST_ADDRESS_WIDTH),
>      DEFINE_PROP_BOOL("caching-mode", IntelIOMMUState, caching_mode, FALSE),
> -    DEFINE_PROP_BOOL("x-scalable-mode", IntelIOMMUState, scalable_mode, 
> FALSE),
> +    DEFINE_PROP_STRING("x-scalable-mode", IntelIOMMUState, scalable_mode),
>      DEFINE_PROP_BOOL("dma-drain", IntelIOMMUState, dma_drain, true),
>      DEFINE_PROP_END_OF_LIST(),
>  };
> @@ -3581,7 +3581,12 @@ static void vtd_init(IntelIOMMUState *s)
>  
>      /* TODO: read cap/ecap from host to decide which cap to be exposed. */
>      if (s->scalable_mode) {
> -        s->ecap |= VTD_ECAP_SMTS | VTD_ECAP_SRS | VTD_ECAP_SLTS;
> +        if (!strcmp(s->scalable_mode, "legacy")) {
> +            s->ecap |= VTD_ECAP_SMTS | VTD_ECAP_SRS | VTD_ECAP_SLTS;
> +        } else if (!strcmp(s->scalable_mode, "modern")) {
> +            s->ecap |= VTD_ECAP_SMTS | VTD_ECAP_SRS | VTD_ECAP_PASID
> +                       | VTD_ECAP_FLTS | VTD_ECAP_PSS;
> +        }

Shall we do this string op only once in vtd_decide_config() then keep
it somewhere?

Something like:

  - s->scalable_mode_str to keep the string
  - s->scalable_mode still as a bool to cache the global enablement
  - s->scalable_modern as a bool to keep the mode

?

These could be used in some MMIO path (I think) and parsing strings
always could be a bit overkill.

>      }
>  
>      vtd_reset_caches(s);
> @@ -3700,6 +3705,12 @@ static bool vtd_decide_config(IntelIOMMUState *s, 
> Error **errp)
>          return false;
>      }
>  
> +    if (s->scalable_mode &&
> +        (strcmp(s->scalable_mode, "modern") &&
> +         strcmp(s->scalable_mode, "legacy"))) {
> +            error_setg(errp, "Invalid x-scalable-mode config");
> +    }
> +
>      return true;
>  }
>  
> diff --git a/hw/i386/intel_iommu_internal.h b/hw/i386/intel_iommu_internal.h
> index c1235a7..be7b30a 100644
> --- a/hw/i386/intel_iommu_internal.h
> +++ b/hw/i386/intel_iommu_internal.h
> @@ -190,8 +190,11 @@
>  #define VTD_ECAP_PT                 (1ULL << 6)
>  #define VTD_ECAP_MHMV               (15ULL << 20)
>  #define VTD_ECAP_SRS                (1ULL << 31)
> +#define VTD_ECAP_PSS                (19ULL << 35)
> +#define VTD_ECAP_PASID              (1ULL << 40)
>  #define VTD_ECAP_SMTS               (1ULL << 43)
>  #define VTD_ECAP_SLTS               (1ULL << 46)
> +#define VTD_ECAP_FLTS               (1ULL << 47)
>  
>  /* CAP_REG */
>  /* (offset >> 4) << 24 */
> diff --git a/include/hw/i386/intel_iommu.h b/include/hw/i386/intel_iommu.h
> index 66b931e..6062588 100644
> --- a/include/hw/i386/intel_iommu.h
> +++ b/include/hw/i386/intel_iommu.h
> @@ -231,7 +231,7 @@ struct IntelIOMMUState {
>      uint32_t version;
>  
>      bool caching_mode;              /* RO - is cap CM enabled? */
> -    bool scalable_mode;             /* RO - is Scalable Mode supported? */
> +    char *scalable_mode;            /* RO - Scalable Mode model */
>  
>      dma_addr_t root;                /* Current root table pointer */
>      bool root_scalable;             /* Type of root table (scalable or not) 
> */
> -- 
> 2.7.4
> 

Regards,

-- 
Peter Xu