Re: [PATCH v2 1/6] xen: introduce XEN_DOMCTL_CDF_directmap

[Julien Grall <julien@xxxxxxx>]

Hi Penny,

On 15/10/2021 04:09, Penny Zheng wrote:
> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
> index 0167731ab0..37e2d62d47 100644
> --- a/xen/arch/arm/domain_build.c
> +++ b/xen/arch/arm/domain_build.c
> @@ -3069,8 +3069,10 @@ static int __init construct_dom0(struct domain *d)
>   void __init create_dom0(void)
>   {
>       struct domain *dom0;
> +    /* DOM0 has always its memory directly mapped. */
>       struct xen_domctl_createdomain dom0_cfg = {
> -        .flags = XEN_DOMCTL_CDF_hvm | XEN_DOMCTL_CDF_hap,
> +        .flags = XEN_DOMCTL_CDF_hvm | XEN_DOMCTL_CDF_hap |
> +                 XEN_DOMCTL_CDF_directmap,
>           .max_evtchn_port = -1,
>           .max_grant_frames = gnttab_dom0_frames(),
>           .max_maptrack_frames = -1,
> diff --git a/xen/common/domain.c b/xen/common/domain.c
> index 8b53c49d1e..7a6131db74 100644
> --- a/xen/common/domain.c
> +++ b/xen/common/domain.c
> @@ -486,7 +486,8 @@ static int sanitise_domain_config(struct 
> xen_domctl_createdomain *config)
>            ~(XEN_DOMCTL_CDF_hvm | XEN_DOMCTL_CDF_hap |
>              XEN_DOMCTL_CDF_s3_integrity | XEN_DOMCTL_CDF_oos_off |
>              XEN_DOMCTL_CDF_xs_domain | XEN_DOMCTL_CDF_iommu |
> -           XEN_DOMCTL_CDF_nested_virt | XEN_DOMCTL_CDF_vpmu) )
> +           XEN_DOMCTL_CDF_nested_virt | XEN_DOMCTL_CDF_vpmu |
> +           XEN_DOMCTL_CDF_directmap) )
>       {
>           dprintk(XENLOG_INFO, "Unknown CDF flags %#x\n", config->flags);
>           return -EINVAL;
> diff --git a/xen/include/asm-arm/domain.h b/xen/include/asm-arm/domain.h
> index 14e575288f..fc42c6a310 100644
> --- a/xen/include/asm-arm/domain.h
> +++ b/xen/include/asm-arm/domain.h
> @@ -29,8 +29,8 @@ enum domain_type {
>   #define is_64bit_domain(d) (0)
>   #endif
>   
> -/* The hardware domain has always its memory direct mapped. */
> -#define is_domain_direct_mapped(d) is_hardware_domain(d)
> +/* Check if domain is direct-map memory map. */
> +#define is_domain_direct_mapped(d) (d->options & XEN_DOMCTL_CDF_directmap)
>   
>   struct vtimer {
>       struct vcpu *v;
> diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h
> index 238384b5ae..b505a0db51 100644
> --- a/xen/include/public/domctl.h
> +++ b/xen/include/public/domctl.h
> @@ -72,9 +72,11 @@ struct xen_domctl_createdomain {
>   #define XEN_DOMCTL_CDF_nested_virt    (1U << _XEN_DOMCTL_CDF_nested_virt)
>   /* Should we expose the vPMU to the guest? */
>   #define XEN_DOMCTL_CDF_vpmu           (1U << 7)
> +/* If this domain has its memory directly mapped? (ARM only) */
> +#define XEN_DOMCTL_CDF_directmap      (1U << 8)
>   
>   /* Max XEN_DOMCTL_CDF_* constant.  Used for ABI checking. */
> -#define XEN_DOMCTL_CDF_MAX XEN_DOMCTL_CDF_vpmu
> +#define XEN_DOMCTL_CDF_MAX XEN_DOMCTL_CDF_directmap
In the previous version, this flag was only settable for domain created 
by Xen. Now this is also settable by the toolstack. I don't think the 
toolstack can sensibly use this flag (at least in the current state).
So can you explain why this flag is exposed to the toolstack?

Cheers,

--
Julien Grall