Re: [Xen-devel] [PATCH v13 0/4] add per-domain IOMMU control

[Oleksandr <olekstysh@xxxxxxxxx>]

On 25.09.19 19:10, Paul Durrant wrote:

Hi Paul

> > -----Original Message-----
> > From: Oleksandr <olekstysh@xxxxxxxxx>
> > Sent: 25 September 2019 16:50
> > To: Paul Durrant <Paul.Durrant@xxxxxxxxxx>; 'Jan Beulich' <jbeulich@xxxxxxxx>
> > Cc: Petre Pircalabu <ppircalabu@xxxxxxxxxxxxxxx>; Stefano Stabellini 
> > <sstabellini@xxxxxxxxxx>; Wei Liu
> > <wl@xxxxxxx>; KonradRzeszutek Wilk <konrad.wilk@xxxxxxxxxx>; Andrew Cooper
> > <Andrew.Cooper3@xxxxxxxxxx>; David Scott <dave@xxxxxxxxxx>; Tim (Xen.org) 
> > <tim@xxxxxxx>; George Dunlap
> > <George.Dunlap@xxxxxxxxxx>; Tamas K Lengyel <tamas@xxxxxxxxxxxxx>; Ian Jackson
> > <Ian.Jackson@xxxxxxxxxx>; Anthony Perard <anthony.perard@xxxxxxxxxx>; 
> > xen-devel@xxxxxxxxxxxxxxxxxxxx;
> > Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>; Roger Pau Monne 
> > <roger.pau@xxxxxxxxxx>; Julien Grall
> > <julien.grall@xxxxxxx>
> > Subject: Re: [Xen-devel] [PATCH v13 0/4] add per-domain IOMMU control
> >
> >
> > [CC Julien]
> >
> >
> > Hi Paul
> >
> > I may mistake, but looks like
> >
> > 80ff3d338dc93260b41ffeeebb0f852c2edef9ce iommu: tidy up
> > iommu_use_hap_pt() and need_iommu_pt_sync() macros
> >
> > triggers ASSERT_UNREACHABLE on Arm if no IOMMU has been found (I built
> > with my platform's IOMMU driver disabled: # CONFIG_IPMMU_VMSA is not set) .
> >
> > So, iommu_setup() calls clear_iommu_hap_pt_share() with
> > iommu_hap_pt_share being set (CONFIG_IOMMU_FORCE_PT_SHARE=y) which,
> > actually, triggers ASSERT.
> Here a minimal patch, leaving 'force pt share' in place. Does this avoid the 
> problem?
>
> ---8<---
> diff --git a/xen/common/sysctl.c b/xen/common/sysctl.c
> index e8763c7fdf..f88a285e7f 100644
> --- a/xen/common/sysctl.c
> +++ b/xen/common/sysctl.c
> @@ -268,9 +268,11 @@ long do_sysctl(XEN_GUEST_HANDLE_PARAM(xen_sysctl_t) 
> u_sysctl)
>           pi->max_mfn = get_upper_mfn_bound();
>           arch_do_physinfo(pi);
>           if ( iommu_enabled )
> +        {
>               pi->capabilities |= XEN_SYSCTL_PHYSCAP_directio;
> -        if ( iommu_hap_pt_share )
> -            pi->capabilities |= XEN_SYSCTL_PHYSCAP_iommu_hap_pt_share;
> +            if ( iommu_hap_pt_share )
> +                pi->capabilities |= XEN_SYSCTL_PHYSCAP_iommu_hap_pt_share;
> +        }
>
>           if ( copy_to_guest(u_sysctl, op, 1) )
>               ret = -EFAULT;
> diff --git a/xen/include/xen/iommu.h b/xen/include/xen/iommu.h
> index 7c3003f3f1..6a10a24128 100644
> --- a/xen/include/xen/iommu.h
> +++ b/xen/include/xen/iommu.h
> @@ -68,8 +68,6 @@ static inline void clear_iommu_hap_pt_share(void)
>   {
>   #ifndef iommu_hap_pt_share
>       iommu_hap_pt_share = false;
> -#elif iommu_hap_pt_share
> -    ASSERT_UNREACHABLE();
>   #endif
>   }
> ---8<---
>
>    Paul
Thank you for the patch, but I need some time to check it (now I have 
some troubles with starting guest VM). I will inform you once I check.

--
Regards,

Oleksandr Tyshchenko


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