Re: [Xen-devel] [PATCH v8 4/6] remove late (on-demand) construction of IOMMU page tables

From: Julien Grall <julien.grall@arm.com>
To: Paul Durrant <paul.durrant@citrix.com>, xen-devel@lists.xenproject.org
Cc: "Petre Pircalabu" <ppircalabu@bitdefender.com>,
	"Stefano Stabellini" <sstabellini@kernel.org>,
	"Wei Liu" <wl@xen.org>,
	"Razvan Cojocaru" <rcojocaru@bitdefender.com>,
	"Konrad Rzeszutek Wilk" <konrad.wilk@oracle.com>,
	"George Dunlap" <George.Dunlap@eu.citrix.com>,
	"Andrew Cooper" <andrew.cooper3@citrix.com>,
	"Ian Jackson" <ian.jackson@eu.citrix.com>,
	"Tim Deegan" <tim@xen.org>,
	"Tamas K Lengyel" <tamas@tklengyel.com>,
	"Jan Beulich" <jbeulich@suse.com>,
	"Alexandru Isaila" <aisaila@bitdefender.com>,
	"Volodymyr Babchuk" <Volodymyr_Babchuk@epam.com>,
	"Roger Pau Monné" <roger.pau@citrix.com>
Subject: Re: [Xen-devel] [PATCH v8 4/6] remove late (on-demand) construction of IOMMU page tables
Date: Thu, 5 Sep 2019 21:21:28 +0100	[thread overview]
Message-ID: <32f4990a-5806-04b8-9bbe-6bdb232bf8e9@arm.com> (raw)
In-Reply-To: <20190902145014.36442-5-paul.durrant@citrix.com>

Hi,

On 9/2/19 3:50 PM, Paul Durrant wrote:
> diff --git a/tools/libxl/libxl_mem.c b/tools/libxl/libxl_mem.c
> index 448a2af8fd..fd6f33312e 100644
> --- a/tools/libxl/libxl_mem.c
> +++ b/tools/libxl/libxl_mem.c
> @@ -461,15 +461,17 @@ int libxl_domain_need_memory(libxl_ctx *ctx,
>       if (rc) goto out;
>   
>       *need_memkb = b_info->target_memkb;
> +    *need_memkb += b_info->shadow_memkb + b_info->iommu_memkb;

AFAICT, iommu_memkb will be non-0 even when the IOMMU share the 
page-table with the CPUs. If so, why is this required for that case?

> +
>       switch (b_info->type) {
>       case LIBXL_DOMAIN_TYPE_PVH:
>       case LIBXL_DOMAIN_TYPE_HVM:
> -        *need_memkb += b_info->shadow_memkb + LIBXL_HVM_EXTRA_MEMORY;
> +        *need_memkb += LIBXL_HVM_EXTRA_MEMORY;
>           if (libxl_defbool_val(b_info->device_model_stubdomain))
>               *need_memkb += 32 * 1024;
>           break;
>       case LIBXL_DOMAIN_TYPE_PV:
> -        *need_memkb += b_info->shadow_memkb + LIBXL_PV_EXTRA_MEMORY;
> +        *need_memkb += LIBXL_PV_EXTRA_MEMORY;
>           break;
>       default:
>           rc = ERROR_INVAL;
> diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
> index b61399ce36..d94b7453cb 100644
> --- a/tools/libxl/libxl_types.idl
> +++ b/tools/libxl/libxl_types.idl
> @@ -486,6 +486,7 @@ libxl_domain_build_info = Struct("domain_build_info",[
>       ("target_memkb",    MemKB),
>       ("video_memkb",     MemKB),
>       ("shadow_memkb",    MemKB),
> +    ("iommu_memkb",     MemKB),

I think you want a corresponding LIBXL_HAVE in libxl.h to tell external 
toolstack whether the field exist.

>       ("rtc_timeoffset",  uint32),
>       ("exec_ssidref",    uint32),
>       ("exec_ssid_label", string),

Cheers,

-- 
Julien Grall

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