Re: [Xen-devel] [PATCH 2/2] x86/p2m: make p2m_alloc_ptp() return an MFN

[George Dunlap <george.dunlap@xxxxxxxxxx>]

On 21/06/17 11:25, Jan Beulich wrote:
> None of the callers really needs the struct page_info pointer.
> 
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

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

> 
> --- a/xen/arch/x86/mm/p2m.c
> +++ b/xen/arch/x86/mm/p2m.c
> @@ -569,7 +569,7 @@ int p2m_set_entry(struct p2m_domain *p2m
>      return rc;
>  }
>  
> -struct page_info *p2m_alloc_ptp(struct p2m_domain *p2m, unsigned long type)
> +mfn_t p2m_alloc_ptp(struct p2m_domain *p2m, unsigned long type)
>  {
>      struct page_info *pg;
>  
> @@ -577,13 +577,13 @@ struct page_info *p2m_alloc_ptp(struct p
>      ASSERT(p2m->domain);
>      ASSERT(p2m->domain->arch.paging.alloc_page);
>      pg = p2m->domain->arch.paging.alloc_page(p2m->domain);
> -    if (pg == NULL)
> -        return NULL;
> +    if ( !pg )
> +        return INVALID_MFN;
>  
>      page_list_add_tail(pg, &p2m->pages);
>      pg->u.inuse.type_info = type | 1 | PGT_validated;
>  
> -    return pg;
> +    return page_to_mfn(pg);
>  }
>  
>  void p2m_free_ptp(struct p2m_domain *p2m, struct page_info *pg)
> @@ -609,7 +609,7 @@ void p2m_free_ptp(struct p2m_domain *p2m
>   */
>  int p2m_alloc_table(struct p2m_domain *p2m)
>  {
> -    struct page_info *p2m_top;
> +    mfn_t top_mfn;
>      struct domain *d = p2m->domain;
>      int rc = 0;
>  
> @@ -632,14 +632,14 @@ int p2m_alloc_table(struct p2m_domain *p
>  
>      P2M_PRINTK("allocating p2m table\n");
>  
> -    p2m_top = p2m_alloc_ptp(p2m, PGT_l4_page_table);
> -    if ( p2m_top == NULL )
> +    top_mfn = p2m_alloc_ptp(p2m, PGT_l4_page_table);
> +    if ( mfn_eq(top_mfn, INVALID_MFN) )
>      {
>          p2m_unlock(p2m);
>          return -ENOMEM;
>      }
>  
> -    p2m->phys_table = pagetable_from_mfn(page_to_mfn(p2m_top));
> +    p2m->phys_table = pagetable_from_mfn(top_mfn);
>  
>      if ( hap_enabled(d) )
>          iommu_share_p2m_table(d);
> --- a/xen/arch/x86/mm/p2m-ept.c
> +++ b/xen/arch/x86/mm/p2m-ept.c
> @@ -225,16 +225,16 @@ static void ept_p2m_type_to_flags(struct
>  /* Fill in middle levels of ept table */
>  static int ept_set_middle_entry(struct p2m_domain *p2m, ept_entry_t 
> *ept_entry)
>  {
> -    struct page_info *pg;
> +    mfn_t mfn;
>      ept_entry_t *table;
>      unsigned int i;
>  
> -    pg = p2m_alloc_ptp(p2m, 0);
> -    if ( pg == NULL )
> +    mfn = p2m_alloc_ptp(p2m, 0);
> +    if ( mfn_eq(mfn, INVALID_MFN) )
>          return 0;
>  
>      ept_entry->epte = 0;
> -    ept_entry->mfn = page_to_mfn(pg);
> +    ept_entry->mfn = mfn_x(mfn);
>      ept_entry->access = p2m->default_access;
>  
>      ept_entry->r = ept_entry->w = ept_entry->x = 1;
> @@ -243,7 +243,7 @@ static int ept_set_middle_entry(struct p
>  
>      ept_entry->suppress_ve = 1;
>  
> -    table = __map_domain_page(pg);
> +    table = map_domain_page(mfn);
>  
>      for ( i = 0; i < EPT_PAGETABLE_ENTRIES; i++ )
>          table[i].suppress_ve = 1;
> --- a/xen/arch/x86/mm/p2m-pt.c
> +++ b/xen/arch/x86/mm/p2m-pt.c
> @@ -195,7 +195,7 @@ p2m_next_level(struct p2m_domain *p2m, v
>      l1_pgentry_t *p2m_entry;
>      l1_pgentry_t new_entry;
>      void *next;
> -    struct page_info *pg;
> +    mfn_t mfn;
>      unsigned int i, flags;
>      unsigned long pfn;
>  
> @@ -206,12 +206,11 @@ p2m_next_level(struct p2m_domain *p2m, v
>      /* PoD/paging: Not present doesn't imply empty. */
>      if ( !l1e_get_flags(*p2m_entry) )
>      {
> -        pg = p2m_alloc_ptp(p2m, type);
> -        if ( pg == NULL )
> +        mfn = p2m_alloc_ptp(p2m, type);
> +        if ( mfn_eq(mfn, INVALID_MFN) )
>              return -ENOMEM;
>  
> -        new_entry = l1e_from_pfn(mfn_x(page_to_mfn(pg)),
> -                                 P2M_BASE_FLAGS | _PAGE_RW);
> +        new_entry = l1e_from_pfn(mfn_x(mfn), P2M_BASE_FLAGS | _PAGE_RW);
>  
>          switch ( type ) {
>          case PGT_l3_page_table:
> @@ -239,11 +238,11 @@ p2m_next_level(struct p2m_domain *p2m, v
>      /* split 1GB pages into 2MB pages */
>      if ( type == PGT_l2_page_table && (flags & _PAGE_PSE) )
>      {
> -        pg = p2m_alloc_ptp(p2m, PGT_l2_page_table);
> -        if ( pg == NULL )
> +        mfn = p2m_alloc_ptp(p2m, PGT_l2_page_table);
> +        if ( mfn_eq(mfn, INVALID_MFN) )
>              return -ENOMEM;
>  
> -        l1_entry = __map_domain_page(pg);
> +        l1_entry = map_domain_page(mfn);
>          for ( i = 0; i < L2_PAGETABLE_ENTRIES; i++ )
>          {
>              new_entry = l1e_from_pfn(pfn | (i * L1_PAGETABLE_ENTRIES), 
> flags);
> @@ -251,8 +250,7 @@ p2m_next_level(struct p2m_domain *p2m, v
>              p2m->write_p2m_entry(p2m, gfn, l1_entry + i, new_entry, 2);
>          }
>          unmap_domain_page(l1_entry);
> -        new_entry = l1e_from_pfn(mfn_x(page_to_mfn(pg)),
> -                                 P2M_BASE_FLAGS | _PAGE_RW); /* disable PSE 
> */
> +        new_entry = l1e_from_pfn(mfn_x(mfn), P2M_BASE_FLAGS | _PAGE_RW);
>          p2m_add_iommu_flags(&new_entry, 2, IOMMUF_readable|IOMMUF_writable);
>          p2m->write_p2m_entry(p2m, gfn, p2m_entry, new_entry, 3);
>      }
> @@ -261,8 +259,8 @@ p2m_next_level(struct p2m_domain *p2m, v
>      /* split single 2MB large page into 4KB page in P2M table */
>      if ( type == PGT_l1_page_table && (flags & _PAGE_PSE) )
>      {
> -        pg = p2m_alloc_ptp(p2m, PGT_l1_page_table);
> -        if ( pg == NULL )
> +        mfn = p2m_alloc_ptp(p2m, PGT_l1_page_table);
> +        if ( mfn_eq(mfn, INVALID_MFN) )
>              return -ENOMEM;
>  
>          /* New splintered mappings inherit the flags of the old superpage, 
> @@ -272,7 +270,7 @@ p2m_next_level(struct p2m_domain *p2m, v
>          else
>              flags &= ~_PAGE_PSE; /* Clear _PAGE_PSE (== _PAGE_PAT) */
>          
> -        l1_entry = __map_domain_page(pg);
> +        l1_entry = map_domain_page(mfn);
>          for ( i = 0; i < L1_PAGETABLE_ENTRIES; i++ )
>          {
>              new_entry = l1e_from_pfn(pfn | i, flags);
> @@ -281,8 +279,7 @@ p2m_next_level(struct p2m_domain *p2m, v
>          }
>          unmap_domain_page(l1_entry);
>          
> -        new_entry = l1e_from_pfn(mfn_x(page_to_mfn(pg)),
> -                                 P2M_BASE_FLAGS | _PAGE_RW);
> +        new_entry = l1e_from_pfn(mfn_x(mfn), P2M_BASE_FLAGS | _PAGE_RW);
>          p2m_add_iommu_flags(&new_entry, 1, IOMMUF_readable|IOMMUF_writable);
>          p2m->write_p2m_entry(p2m, gfn, p2m_entry, new_entry, 2);
>      }
> --- a/xen/include/asm-x86/p2m.h
> +++ b/xen/include/asm-x86/p2m.h
> @@ -684,7 +684,7 @@ void p2m_mem_paging_resume(struct domain
>   * Internal functions, only called by other p2m code
>   */
>  
> -struct page_info *p2m_alloc_ptp(struct p2m_domain *p2m, unsigned long type);
> +mfn_t p2m_alloc_ptp(struct p2m_domain *p2m, unsigned long type);
>  void p2m_free_ptp(struct p2m_domain *p2m, struct page_info *pg);
>  
>  /* Directly set a p2m entry: only for use by p2m code. Does not need
> 
> 


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