Re: [Xen-devel] [PATCH 2/3] x86/mm: Consolidate all Xen L2 slot writing into init_xen_pae_l2_slots()

[George Dunlap <george.dunlap@xxxxxxxxxx>]

On 10/12/2017 02:54 PM, Andrew Cooper wrote:
> Having all of this logic together makes it easier to follow Xen's virtual
> setup across the whole system.
> 
> No functional change.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

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

> ---
> CC: Jan Beulich <JBeulich@xxxxxxxx>
> CC: Tim Deegan <tim@xxxxxxx>
> CC: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
> CC: Wei Liu <wei.liu2@xxxxxxxxxx>
> CC: Julien Grall <julien.grall@xxxxxxx>
> ---
>  xen/arch/x86/mm.c              | 16 +++++++++-------
>  xen/arch/x86/mm/shadow/multi.c | 42 
> +++++++++++++++---------------------------
>  xen/include/asm-x86/mm.h       |  1 +
>  3 files changed, 25 insertions(+), 34 deletions(-)
> 
> diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
> index f90a42a..ea4af16 100644
> --- a/xen/arch/x86/mm.c
> +++ b/xen/arch/x86/mm.c
> @@ -1433,13 +1433,7 @@ static int alloc_l2_table(struct page_info *page, 
> unsigned long type,
>      }
>  
>      if ( rc >= 0 && (type & PGT_pae_xen_l2) )
> -    {
> -        /* Xen private mappings. */
> -        memcpy(&pl2e[COMPAT_L2_PAGETABLE_FIRST_XEN_SLOT(d)],
> -               &compat_idle_pg_table_l2[
> -                   l2_table_offset(HIRO_COMPAT_MPT_VIRT_START)],
> -               COMPAT_L2_PAGETABLE_XEN_SLOTS(d) * sizeof(*pl2e));
> -    }
> +        init_xen_pae_l2_slots(pl2e, d);
>  
>      unmap_domain_page(pl2e);
>      return rc > 0 ? 0 : rc;
> @@ -1518,6 +1512,14 @@ static int alloc_l3_table(struct page_info *page)
>      return rc > 0 ? 0 : rc;
>  }
>  
> +void init_xen_pae_l2_slots(l2_pgentry_t *l2t, const struct domain *d)
> +{
> +    memcpy(&l2t[COMPAT_L2_PAGETABLE_FIRST_XEN_SLOT(d)],
> +           &compat_idle_pg_table_l2[
> +               l2_table_offset(HIRO_COMPAT_MPT_VIRT_START)],
> +           COMPAT_L2_PAGETABLE_XEN_SLOTS(d) * sizeof(*l2t));
> +}
> +
>  /*
>   * This function must write all ROOT_PAGETABLE_PV_XEN_SLOTS, to clobber any
>   * values a guest may have left there from alloc_l4_table().
> diff --git a/xen/arch/x86/mm/shadow/multi.c b/xen/arch/x86/mm/shadow/multi.c
> index d540af1..1b76e0c 100644
> --- a/xen/arch/x86/mm/shadow/multi.c
> +++ b/xen/arch/x86/mm/shadow/multi.c
> @@ -1521,31 +1521,6 @@ void sh_install_xen_entries_in_l4(struct domain *d, 
> mfn_t gl4mfn, mfn_t sl4mfn)
>  }
>  #endif
>  
> -#if GUEST_PAGING_LEVELS >= 3
> -// For 3-on-3 PV guests, we need to make sure the xen mappings are in
> -// place, which means that we need to populate the l2h entry in the l3
> -// table.
> -
> -static void sh_install_xen_entries_in_l2h(struct domain *d, mfn_t sl2hmfn)
> -{
> -    shadow_l2e_t *sl2e;
> -
> -    if ( !is_pv_32bit_domain(d) )
> -        return;
> -
> -    sl2e = map_domain_page(sl2hmfn);
> -    BUILD_BUG_ON(sizeof (l2_pgentry_t) != sizeof (shadow_l2e_t));
> -
> -    /* Copy the common Xen mappings from the idle domain */
> -    memcpy(
> -        &sl2e[COMPAT_L2_PAGETABLE_FIRST_XEN_SLOT(d)],
> -        
> &compat_idle_pg_table_l2[l2_table_offset(HIRO_COMPAT_MPT_VIRT_START)],
> -        COMPAT_L2_PAGETABLE_XEN_SLOTS(d) * sizeof(*sl2e));
> -
> -    unmap_domain_page(sl2e);
> -}
> -#endif
> -
>  
>  /**************************************************************************/
>  /* Create a shadow of a given guest page.
> @@ -1610,7 +1585,14 @@ sh_make_shadow(struct vcpu *v, mfn_t gmfn, u32 
> shadow_type)
>  #endif
>  #if GUEST_PAGING_LEVELS >= 3
>          case SH_type_l2h_shadow:
> -            sh_install_xen_entries_in_l2h(v->domain, smfn);
> +            BUILD_BUG_ON(sizeof(l2_pgentry_t) != sizeof(shadow_l2e_t));
> +            if ( is_pv_32bit_domain(d) )
> +            {
> +                shadow_l2e_t *l2t = map_domain_page(smfn);
> +
> +                init_xen_pae_l2_slots(l2t, d);
> +                unmap_domain_page(l2t);
> +            }
>              break;
>  #endif
>          default: /* Do nothing */ break;
> @@ -1677,6 +1659,8 @@ sh_make_monitor_table(struct vcpu *v)
>  
>              if ( is_pv_32bit_domain(d) )
>              {
> +                l2_pgentry_t *l2t;
> +
>                  /* For 32-bit PV guests, we need to map the 32-bit Xen
>                   * area into its usual VAs in the monitor tables */
>                  m3mfn = shadow_alloc(d, SH_type_monitor_table, 0);
> @@ -1687,7 +1671,11 @@ sh_make_monitor_table(struct vcpu *v)
>                  mfn_to_page(m2mfn)->shadow_flags = 2;
>                  l3e = map_domain_page(m3mfn);
>                  l3e[3] = l3e_from_mfn(m2mfn, _PAGE_PRESENT);
> -                sh_install_xen_entries_in_l2h(d, m2mfn);
> +
> +                l2t = map_domain_page(m2mfn);
> +                init_xen_pae_l2_slots(l2t, d);
> +                unmap_domain_page(l2t);
> +
>                  unmap_domain_page(l3e);
>              }
>  
> diff --git a/xen/include/asm-x86/mm.h b/xen/include/asm-x86/mm.h
> index eeac4d7..da3c5e2 100644
> --- a/xen/include/asm-x86/mm.h
> +++ b/xen/include/asm-x86/mm.h
> @@ -340,6 +340,7 @@ static inline void *__page_to_virt(const struct page_info 
> *pg)
>  int free_page_type(struct page_info *page, unsigned long type,
>                     int preemptible);
>  
> +void init_xen_pae_l2_slots(l2_pgentry_t *l2t, const struct domain *d);
>  void init_guest_l4_table(l4_pgentry_t[], const struct domain *,
>                           bool_t zap_ro_mpt);
>  bool fill_ro_mpt(mfn_t mfn);
> 


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