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Re: [Xen-devel] [PATCH v2] x86/MM: Introduce a p2m class.



On 30/01/15 00:43, Ed White wrote:
> Use the class to differentiate between host and nested p2m's, and
> potentially other classes in the future.
>
> Fix p2m class checks that implicitly assume nested and host are
> the only two classes that will ever exist.
>
> Signed-off-by: Ed White <edmund.h.white@xxxxxxxxx>
> Acked-by: Tim Deegan <tim@xxxxxxx>

Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

>
> ---
>
> Changes in v2:
>     - prepend missing area prefix to description
>     - don't give enum members specific numeric values
>     - constify p2m passed into class checkers
> ---
>  xen/arch/x86/hvm/hvm.c           |  2 +-
>  xen/arch/x86/mm/guest_walk.c     |  2 +-
>  xen/arch/x86/mm/hap/guest_walk.c |  4 ++--
>  xen/arch/x86/mm/p2m-ept.c        |  4 ++--
>  xen/arch/x86/mm/p2m.c            | 10 ++++++----
>  xen/include/asm-x86/p2m.h        | 17 ++++++++++++++++-
>  6 files changed, 28 insertions(+), 11 deletions(-)
>
> diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
> index c7984d1..4c38a40 100644
> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -2859,7 +2859,7 @@ int hvm_hap_nested_page_fault(paddr_t gpa, unsigned 
> long gla,
>      /* Mem sharing: unshare the page and try again */
>      if ( npfec.write_access && (p2mt == p2m_ram_shared) )
>      {
> -        ASSERT(!p2m_is_nestedp2m(p2m));
> +        ASSERT(p2m_is_hostp2m(p2m));
>          sharing_enomem = 
>              (mem_sharing_unshare_page(p2m->domain, gfn, 0) < 0);
>          rc = 1;
> diff --git a/xen/arch/x86/mm/guest_walk.c b/xen/arch/x86/mm/guest_walk.c
> index 1b26175..d8f5a35 100644
> --- a/xen/arch/x86/mm/guest_walk.c
> +++ b/xen/arch/x86/mm/guest_walk.c
> @@ -99,7 +99,7 @@ void *map_domain_gfn(struct p2m_domain *p2m, gfn_t gfn, 
> mfn_t *mfn,
>                                   q);
>      if ( p2m_is_paging(*p2mt) )
>      {
> -        ASSERT(!p2m_is_nestedp2m(p2m));
> +        ASSERT(p2m_is_hostp2m(p2m));
>          if ( page )
>              put_page(page);
>          p2m_mem_paging_populate(p2m->domain, gfn_x(gfn));
> diff --git a/xen/arch/x86/mm/hap/guest_walk.c 
> b/xen/arch/x86/mm/hap/guest_walk.c
> index 25d9792..381a196 100644
> --- a/xen/arch/x86/mm/hap/guest_walk.c
> +++ b/xen/arch/x86/mm/hap/guest_walk.c
> @@ -64,7 +64,7 @@ unsigned long hap_p2m_ga_to_gfn(GUEST_PAGING_LEVELS)(
>                                       &p2mt, NULL, P2M_ALLOC | P2M_UNSHARE);
>      if ( p2m_is_paging(p2mt) )
>      {
> -        ASSERT(!p2m_is_nestedp2m(p2m));
> +        ASSERT(p2m_is_hostp2m(p2m));
>          pfec[0] = PFEC_page_paged;
>          if ( top_page )
>              put_page(top_page);
> @@ -106,7 +106,7 @@ unsigned long hap_p2m_ga_to_gfn(GUEST_PAGING_LEVELS)(
>              put_page(page);
>          if ( p2m_is_paging(p2mt) )
>          {
> -            ASSERT(!p2m_is_nestedp2m(p2m));
> +            ASSERT(p2m_is_hostp2m(p2m));
>              pfec[0] = PFEC_page_paged;
>              p2m_mem_paging_populate(p2m->domain, gfn_x(gfn));
>              return INVALID_GFN;
> diff --git a/xen/arch/x86/mm/p2m-ept.c b/xen/arch/x86/mm/p2m-ept.c
> index e21a92d..c2d7720 100644
> --- a/xen/arch/x86/mm/p2m-ept.c
> +++ b/xen/arch/x86/mm/p2m-ept.c
> @@ -769,8 +769,8 @@ out:
>      if ( needs_sync != sync_off )
>          ept_sync_domain(p2m);
>  
> -    /* For non-nested p2m, may need to change VT-d page table.*/
> -    if ( rc == 0 && !p2m_is_nestedp2m(p2m) && need_iommu(d) &&
> +    /* For host p2m, may need to change VT-d page table.*/
> +    if ( rc == 0 && p2m_is_hostp2m(p2m) && need_iommu(d) &&
>           need_modify_vtd_table )
>      {
>          if ( iommu_hap_pt_share )
> diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
> index efa49dd..4434b9a 100644
> --- a/xen/arch/x86/mm/p2m.c
> +++ b/xen/arch/x86/mm/p2m.c
> @@ -71,6 +71,7 @@ static int p2m_initialise(struct domain *d, struct 
> p2m_domain *p2m)
>  
>      p2m->domain = d;
>      p2m->default_access = p2m_access_rwx;
> +    p2m->p2m_class = p2m_host;
>  
>      p2m->np2m_base = P2M_BASE_EADDR;
>  
> @@ -158,6 +159,7 @@ static int p2m_init_nestedp2m(struct domain *d)
>              p2m_teardown_nestedp2m(d);
>              return -ENOMEM;
>          }
> +        p2m->p2m_class = p2m_nested;
>          p2m->write_p2m_entry = nestedp2m_write_p2m_entry;
>          list_add(&p2m->np2m_list, &p2m_get_hostp2m(d)->np2m_list);
>      }
> @@ -202,7 +204,7 @@ int p2m_init(struct domain *d)
>  int p2m_is_logdirty_range(struct p2m_domain *p2m, unsigned long start,
>                            unsigned long end)
>  {
> -    ASSERT(!p2m_is_nestedp2m(p2m));
> +    ASSERT(p2m_is_hostp2m(p2m));
>      if ( p2m->global_logdirty ||
>           rangeset_contains_range(p2m->logdirty_ranges, start, end) )
>          return 1;
> @@ -263,7 +265,7 @@ mfn_t __get_gfn_type_access(struct p2m_domain *p2m, 
> unsigned long gfn,
>  
>      if ( (q & P2M_UNSHARE) && p2m_is_shared(*t) )
>      {
> -        ASSERT(!p2m_is_nestedp2m(p2m));
> +        ASSERT(p2m_is_hostp2m(p2m));
>          /* Try to unshare. If we fail, communicate ENOMEM without
>           * sleeping. */
>          if ( mem_sharing_unshare_page(p2m->domain, gfn, 0) < 0 )
> @@ -431,7 +433,7 @@ int p2m_alloc_table(struct p2m_domain *p2m)
>  
>      p2m_lock(p2m);
>  
> -    if ( !p2m_is_nestedp2m(p2m)
> +    if ( p2m_is_hostp2m(p2m)
>           && !page_list_empty(&d->page_list) )
>      {
>          P2M_ERROR("dom %d already has memory allocated\n", d->domain_id);
> @@ -1708,7 +1710,7 @@ p2m_flush_table(struct p2m_domain *p2m)
>  
>      /* "Host" p2m tables can have shared entries &c that need a bit more 
>       * care when discarding them */
> -    ASSERT(p2m_is_nestedp2m(p2m));
> +    ASSERT(!p2m_is_hostp2m(p2m));
>      /* Nested p2m's do not do pod, hence the asserts (and no pod lock)*/
>      ASSERT(page_list_empty(&p2m->pod.super));
>      ASSERT(page_list_empty(&p2m->pod.single));
> diff --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h
> index 2cf73ca..8742725 100644
> --- a/xen/include/asm-x86/p2m.h
> +++ b/xen/include/asm-x86/p2m.h
> @@ -172,6 +172,11 @@ typedef unsigned int p2m_query_t;
>                               (P2M_RAM_TYPES | P2M_GRANT_TYPES |  \
>                                p2m_to_mask(p2m_map_foreign)))
>  
> +typedef enum {
> +    p2m_host,
> +    p2m_nested,
> +} p2m_class_t;
> +
>  /* Per-p2m-table state */
>  struct p2m_domain {
>      /* Lock that protects updates to the p2m */
> @@ -188,6 +193,8 @@ struct p2m_domain {
>  
>      struct domain     *domain;   /* back pointer to domain */
>  
> +    p2m_class_t       p2m_class; /* host/nested/? */
> +
>      /* Nested p2ms only: nested p2m base value that this p2m shadows.
>       * This can be cleared to P2M_BASE_EADDR under the per-p2m lock but
>       * needs both the per-p2m lock and the per-domain nestedp2m lock
> @@ -297,7 +304,15 @@ struct p2m_domain *p2m_get_nestedp2m(struct vcpu *v, 
> uint64_t np2m_base);
>   */
>  struct p2m_domain *p2m_get_p2m(struct vcpu *v);
>  
> -#define p2m_is_nestedp2m(p2m)   ((p2m) != p2m_get_hostp2m((p2m->domain)))
> +static inline bool_t p2m_is_hostp2m(const struct p2m_domain *p2m)
> +{
> +    return p2m->p2m_class == p2m_host;
> +}
> +
> +static inline bool_t p2m_is_nestedp2m(const struct p2m_domain *p2m)
> +{
> +    return p2m->p2m_class == p2m_nested;
> +}
>  
>  #define p2m_get_pagetable(p2m)  ((p2m)->phys_table)
>  


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