Re: [Xen-devel] [PATCH V3] xen/altp2m: set access_required properly for all altp2ms

[George Dunlap <george.dunlap@xxxxxxxxxx>]

On 06/28/2018 08:54 AM, Razvan Cojocaru wrote:
> For the hostp2m, access_required starts off as 0, then it can be
> set with xc_domain_set_access_required(). However, all the altp2ms
> set it to 1 on init, and ignore both the hostp2m and the hypercall.
> This patch sets access_required to the value from the hostp2m
> on altp2m init, and propagates the values received via hypercall
> to all the active altp2ms, when applicable.
> 
> Signed-off-by: Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>

Reviewed-by: George Dunlap <george.dunlap@xxxxxxxxxx>

> 
> ---
> Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> Cc: Julien Grall <julien.grall@xxxxxxx>
> Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Cc: George Dunlap <George.Dunlap@xxxxxxxxxxxxx>
> Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
> Cc: Jan Beulich <jbeulich@xxxxxxxx>
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> Cc: Tim Deegan <tim@xxxxxxx>
> Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
> Cc: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
> Cc: Tamas K Lengyel <tamas@xxxxxxxxxxxxx>
> ---
> Changes since V2:
>  - Renamed arch_domain_set_access_required() to
>    arch_p2m_set_access_required() (requested by Wei Liu).
>  - Added ASSERT(atomic_read(&d->pause_count)) to
>    arch_p2m_set_access_required() (requested by Wei Liu).
> ---
>  xen/arch/arm/mem_access.c    |  6 ++++++
>  xen/arch/x86/mm/mem_access.c | 20 ++++++++++++++++++++
>  xen/arch/x86/mm/p2m.c        |  3 ++-
>  xen/common/domctl.c          |  4 ++--
>  xen/include/xen/domain.h     |  2 ++
>  5 files changed, 32 insertions(+), 3 deletions(-)
> 
> diff --git a/xen/arch/arm/mem_access.c b/xen/arch/arm/mem_access.c
> index ae2686f..ba4ec78 100644
> --- a/xen/arch/arm/mem_access.c
> +++ b/xen/arch/arm/mem_access.c
> @@ -453,6 +453,12 @@ int p2m_get_mem_access(struct domain *d, gfn_t gfn,
>      return ret;
>  }
>  
> +void arch_p2m_set_access_required(struct domain *d, bool access_required)
> +{
> +    ASSERT(atomic_read(&d->pause_count));
> +    p2m_get_hostp2m(d)->access_required = access_required;
> +}
> +
>  /*
>   * Local variables:
>   * mode: C
> diff --git a/xen/arch/x86/mm/mem_access.c b/xen/arch/x86/mm/mem_access.c
> index c0cd017..464be49 100644
> --- a/xen/arch/x86/mm/mem_access.c
> +++ b/xen/arch/x86/mm/mem_access.c
> @@ -465,6 +465,26 @@ int p2m_get_mem_access(struct domain *d, gfn_t gfn, 
> xenmem_access_t *access)
>      return _p2m_get_mem_access(p2m, gfn, access);
>  }
>  
> +void arch_p2m_set_access_required(struct domain *d, bool access_required)
> +{
> +    unsigned int i;
> +
> +    ASSERT(atomic_read(&d->pause_count));
> +
> +    p2m_get_hostp2m(d)->access_required = access_required;
> +
> +    if ( !altp2m_active(d) )
> +        return;
> +
> +    for ( i = 0; i < MAX_ALTP2M; i++ )
> +    {
> +        struct p2m_domain *p2m = d->arch.altp2m_p2m[i];
> +
> +        if ( p2m )
> +            p2m->access_required = access_required;
> +    }
> +}
> +
>  /*
>   * Local variables:
>   * mode: C
> diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
> index c53cab4..8e9fbb5 100644
> --- a/xen/arch/x86/mm/p2m.c
> +++ b/xen/arch/x86/mm/p2m.c
> @@ -199,6 +199,7 @@ static int p2m_init_altp2m(struct domain *d)
>  {
>      unsigned int i;
>      struct p2m_domain *p2m;
> +    struct p2m_domain *hostp2m = p2m_get_hostp2m(d);
>  
>      mm_lock_init(&d->arch.altp2m_list_lock);
>      for ( i = 0; i < MAX_ALTP2M; i++ )
> @@ -210,7 +211,7 @@ static int p2m_init_altp2m(struct domain *d)
>              return -ENOMEM;
>          }
>          p2m->p2m_class = p2m_alternate;
> -        p2m->access_required = 1;
> +        p2m->access_required = hostp2m->access_required;
>          _atomic_set(&p2m->active_vcpus, 0);
>      }
>  
> diff --git a/xen/common/domctl.c b/xen/common/domctl.c
> index 9b7bc08..789b30d 100644
> --- a/xen/common/domctl.c
> +++ b/xen/common/domctl.c
> @@ -1092,8 +1092,8 @@ long do_domctl(XEN_GUEST_HANDLE_PARAM(xen_domctl_t) 
> u_domctl)
>          else
>          {
>              domain_pause(d);
> -            p2m_get_hostp2m(d)->access_required =
> -                op->u.access_required.access_required;
> +            arch_p2m_set_access_required(d,
> +                op->u.access_required.access_required);
>              domain_unpause(d);
>          }
>          break;
> diff --git a/xen/include/xen/domain.h b/xen/include/xen/domain.h
> index 177cb35..f35e360 100644
> --- a/xen/include/xen/domain.h
> +++ b/xen/include/xen/domain.h
> @@ -66,6 +66,8 @@ void arch_domain_unpause(struct domain *d);
>  
>  int arch_domain_soft_reset(struct domain *d);
>  
> +void arch_p2m_set_access_required(struct domain *d, bool access_required);
> +
>  int arch_set_info_guest(struct vcpu *, vcpu_guest_context_u);
>  void arch_get_info_guest(struct vcpu *, vcpu_guest_context_u);
>  
> 


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