Re: [RFC PATCH 03/20] intel_iommu: add "svm" option

Peter Xu
2017-04-27T10:53:17Z

On Wed, Apr 26, 2017 at 06:06:33PM +0800, Liu, Yi L wrote:
> Expose "Shared Virtual Memory" to guest by using "svm" option.
> Also use "svm" to expose SVM related capabilities to guest.
> e.g. "-device intel-iommu, svm=on"
>
> Signed-off-by: Liu, Yi L <yi.l.liu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
> ---
> hw/i386/intel_iommu.c | 10 ++++++++++
> hw/i386/intel_iommu_internal.h | 5 +++++
> include/hw/i386/intel_iommu.h | 1 +
> 3 files changed, 16 insertions(+)
>
> diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
> index bf98fa5..ba1e7eb 100644
> --- a/hw/i386/intel_iommu.c
> +++ b/hw/i386/intel_iommu.c
> @@ -2453,6 +2453,7 @@ static Property vtd_properties[] = {
> DEFINE_PROP_BOOL("x-buggy-eim", IntelIOMMUState, buggy_eim, false),
> DEFINE_PROP_BOOL("caching-mode", IntelIOMMUState, caching_mode, FALSE),
> DEFINE_PROP_BOOL("ecs", IntelIOMMUState, ecs, FALSE),
> + DEFINE_PROP_BOOL("svm", IntelIOMMUState, svm, FALSE),
> DEFINE_PROP_END_OF_LIST(),
> };
>
> @@ -2973,6 +2974,15 @@ static void vtd_init(IntelIOMMUState *s)
> s->ecap |= VTD_ECAP_ECS;
> }
>
> + if (s->svm) {
> + if (!s->ecs || !x86_iommu->pt_supported || !s->caching_mode) {
> + error_report("Need to set ecs, pt, caching-mode for svm");
> + exit(1);
> + }
> + s->cap |= VTD_CAP_DWD | VTD_CAP_DRD;
> + s->ecap |= VTD_ECAP_PRS | VTD_ECAP_PTS | VTD_ECAP_PASID28;
> + }
> +
> if (s->caching_mode) {
> s->cap |= VTD_CAP_CM;
> }
> diff --git a/hw/i386/intel_iommu_internal.h b/hw/i386/intel_iommu_internal.h
> index 71a1c1e..f2a7d12 100644
> --- a/hw/i386/intel_iommu_internal.h
> +++ b/hw/i386/intel_iommu_internal.h
> @@ -191,6 +191,9 @@
> #define VTD_ECAP_PT (1ULL << 6)
> #define VTD_ECAP_MHMV (15ULL << 20)
> #define VTD_ECAP_ECS (1ULL << 24)
> +#define VTD_ECAP_PASID28 (1ULL << 28)

Could I ask what's this bit? On my spec, it says this bit is reserved
and defunct (spec version: June 2016).

> +#define VTD_ECAP_PRS (1ULL << 29)
> +#define VTD_ECAP_PTS (0xeULL << 35)

Would it better we avoid using 0xe here, or at least add some comment?

>
> /* CAP_REG */
> /* (offset >> 4) << 24 */
> @@ -207,6 +210,8 @@
> #define VTD_CAP_PSI (1ULL << 39)
> #define VTD_CAP_SLLPS ((1ULL << 34) | (1ULL << 35))
> #define VTD_CAP_CM (1ULL << 7)
> +#define VTD_CAP_DWD (1ULL << 54)
> +#define VTD_CAP_DRD (1ULL << 55)

Just to confirm: after this series, we should support drain read/write
then, right?

Thanks,

>
> /* Supported Adjusted Guest Address Widths */
> #define VTD_CAP_SAGAW_SHIFT 8
> diff --git a/include/hw/i386/intel_iommu.h b/include/hw/i386/intel_iommu.h
> index ae21fe5..8981615 100644
> --- a/include/hw/i386/intel_iommu.h
> +++ b/include/hw/i386/intel_iommu.h
> @@ -267,6 +267,7 @@ struct IntelIOMMUState {
>
> bool caching_mode; /* RO - is cap CM enabled? */
> bool ecs; /* Extended Context Support */
> + bool svm; /* Shared Virtual Memory */
>
> dma_addr_t root; /* Current root table pointer */
> bool root_extended; /* Type of root table (extended or not) */
> --
> 1.9.1
>

--
Peter Xu