Re: [PATCH v1 16/17] intel_iommu: Modify x-scalable-mode to be string option

[CLEMENT MATHIEU--DRIF]

On 18/07/2024 10:16, Zhenzhong Duan wrote:
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>
> From: Yi Liu <yi.l.liu@intel.com>
>
> 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 to 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"|"off"]"
>
>   - "legacy": gives support for stage-2 page table
>   - "modern": gives support for stage-1 page table
>   - "off": no scalable mode support
>   -  if not configured, means no scalable mode support, if not proper
>      configured, will throw error
s/proper/properly
Maybe we could split and rephrase the last bullet point to make it clear 
that "off" is equivalent to not using the option at all
>
> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
> Signed-off-by: Yi Sun <yi.y.sun@linux.intel.com>
> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
> ---
>   include/hw/i386/intel_iommu.h |  1 +
>   hw/i386/intel_iommu.c         | 24 +++++++++++++++++++++++-
>   2 files changed, 24 insertions(+), 1 deletion(-)
>
> diff --git a/include/hw/i386/intel_iommu.h b/include/hw/i386/intel_iommu.h
> index 48134bda11..650641544c 100644
> --- a/include/hw/i386/intel_iommu.h
> +++ b/include/hw/i386/intel_iommu.h
> @@ -263,6 +263,7 @@ struct IntelIOMMUState {
>
>       bool caching_mode;              /* RO - is cap CM enabled? */
>       bool scalable_mode;             /* RO - is Scalable Mode supported? */
> +    char *scalable_mode_str;        /* RO - admin's Scalable Mode config */
>       bool scalable_modern;           /* RO - is modern SM supported? */
>       bool snoop_control;             /* RO - is SNP filed supported? */
>
> diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
> index 2804c3628a..14d05fce1d 100644
> --- a/hw/i386/intel_iommu.c
> +++ b/hw/i386/intel_iommu.c
> @@ -3770,7 +3770,7 @@ static Property vtd_properties[] = {
>       DEFINE_PROP_UINT8("aw-bits", IntelIOMMUState, aw_bits,
>                         VTD_HOST_AW_AUTO),
>       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_str),
>       DEFINE_PROP_BOOL("snoop-control", IntelIOMMUState, snoop_control, 
> false),
>       DEFINE_PROP_BOOL("x-pasid-mode", IntelIOMMUState, pasid, false),
>       DEFINE_PROP_BOOL("dma-drain", IntelIOMMUState, dma_drain, true),
> @@ -4686,6 +4686,28 @@ static bool vtd_decide_config(IntelIOMMUState *s, 
> Error **errp)
>           }
>       }
>
> +    if (s->scalable_mode_str &&
> +        (strcmp(s->scalable_mode_str, "off") &&
> +         strcmp(s->scalable_mode_str, "modern") &&
> +         strcmp(s->scalable_mode_str, "legacy"))) {
> +        error_setg(errp, "Invalid x-scalable-mode config,"
> +                         "Please use \"modern\", \"legacy\" or \"off\"");
> +        return false;
> +    }
> +
> +    if (s->scalable_mode_str &&
> +        !strcmp(s->scalable_mode_str, "legacy")) {
> +        s->scalable_mode = true;
> +        s->scalable_modern = false;
> +    } else if (s->scalable_mode_str &&
> +        !strcmp(s->scalable_mode_str, "modern")) {
> +        s->scalable_mode = true;
> +        s->scalable_modern = true;
> +    } else {
> +        s->scalable_mode = false;
> +        s->scalable_modern = false;
> +    }
> +
>       if (s->aw_bits == VTD_HOST_AW_AUTO) {
>           if (s->scalable_modern) {
>               s->aw_bits = VTD_HOST_AW_48BIT;
> --
> 2.34.1
>
LGTM