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Re: [Xen-devel] [PATCH V13 1/7] xen/arm: p2m changes for mem_access support



On Fri, 6 Mar 2015, Tamas K Lengyel wrote:
> Add necessary changes for page table construction routines to pass
> the default access information. We store the p2m_access_t info in a
> Radix tree as the PTE lacks enough software programmable bits.
> 
> Signed-off-by: Tamas K Lengyel <tklengyel@xxxxxxxxxxxxx>
> ---
> v13: - Rename access_in_use to mem_access_enabled.
>      - Define p2m_get_mem_access function prototype but
>         return -ENOSYS for now.
> v11: - Move including common/mem_event.h down the series.
> v10: - Typo fix and drop reshuffling things that no longer need
>       shuffling.
> v8: - Drop lock inputs as common mem_access_check is postponed.
>     - Resurrect the radix tree with an extra boolean access_in_use flag
>       to indicate if the tree is empty to avoid lookups.
> v7: - Remove radix tree init/destroy and move p2m_access_t store to page_info.
>     - Add p2m_gpfn_lock/unlock functions.
>     - Add bool_t lock input to p2m_lookup and apply_p2m_changes so the caller
>       can specify if locking should be performed. This is needed in order to
>       support mem_access_check from common.
> v6: - Move mem_event header include to first patch that needs it.
> v5: - #include grouping style-fix.
> v4: - Move p2m_get_hostp2m definition here.
> ---
>  xen/arch/arm/p2m.c              | 52 
> +++++++++++++++++++++++++++--------------
>  xen/include/asm-arm/domain.h    |  1 +
>  xen/include/asm-arm/p2m.h       | 35 ++++++++++++++++++++++++++-
>  xen/include/asm-arm/processor.h |  2 +-
>  4 files changed, 70 insertions(+), 20 deletions(-)
> 
> diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> index 8809f5a..137e5a0 100644
> --- a/xen/arch/arm/p2m.c
> +++ b/xen/arch/arm/p2m.c
> @@ -305,7 +305,7 @@ static void p2m_set_permission(lpae_t *e, p2m_type_t t, 
> p2m_access_t a)
>  }
>  
>  static lpae_t mfn_to_p2m_entry(unsigned long mfn, unsigned int mattr,
> -                               p2m_type_t t)
> +                               p2m_type_t t, p2m_access_t a)
>  {
>      paddr_t pa = ((paddr_t) mfn) << PAGE_SHIFT;
>      /* sh, xn and write bit will be defined in the following switches
> @@ -335,8 +335,7 @@ static lpae_t mfn_to_p2m_entry(unsigned long mfn, 
> unsigned int mattr,
>          break;
>      }
>  
> -    /* We pass p2m_access_rwx as a placeholder for now. */
> -    p2m_set_permission(&e, t, p2m_access_rwx);
> +    p2m_set_permission(&e, t, a);
>  
>      ASSERT(!(pa & ~PAGE_MASK));
>      ASSERT(!(pa & ~PADDR_MASK));
> @@ -394,7 +393,7 @@ static int p2m_create_table(struct domain *d, lpae_t 
> *entry,
>           for ( i=0 ; i < LPAE_ENTRIES; i++ )
>           {
>               pte = mfn_to_p2m_entry(base_pfn + (i<<(level_shift-LPAE_SHIFT)),
> -                                    MATTR_MEM, t);
> +                                    MATTR_MEM, t, p2m->default_access);
>  
>               /*
>                * First and second level super pages set p2m.table = 0, but
> @@ -414,7 +413,8 @@ static int p2m_create_table(struct domain *d, lpae_t 
> *entry,
>  
>      unmap_domain_page(p);
>  
> -    pte = mfn_to_p2m_entry(page_to_mfn(page), MATTR_MEM, p2m_invalid);
> +    pte = mfn_to_p2m_entry(page_to_mfn(page), MATTR_MEM, p2m_invalid,
> +                           p2m->default_access);
>  
>      p2m_write_pte(entry, pte, flush_cache);
>  
> @@ -537,7 +537,8 @@ static int apply_one_level(struct domain *d,
>                             paddr_t *maddr,
>                             bool_t *flush,
>                             int mattr,
> -                           p2m_type_t t)
> +                           p2m_type_t t,
> +                           p2m_access_t a)
>  {
>      const paddr_t level_size = level_sizes[level];
>      const paddr_t level_mask = level_masks[level];
> @@ -566,7 +567,7 @@ static int apply_one_level(struct domain *d,
>              page = alloc_domheap_pages(d, level_shift - PAGE_SHIFT, 0);
>              if ( page )
>              {
> -                pte = mfn_to_p2m_entry(page_to_mfn(page), mattr, t);
> +                pte = mfn_to_p2m_entry(page_to_mfn(page), mattr, t, a);
>                  if ( level < 3 )
>                      pte.p2m.table = 0;
>                  p2m_write_pte(entry, pte, flush_cache);
> @@ -601,7 +602,7 @@ static int apply_one_level(struct domain *d,
>               (level == 3 || !p2m_table(orig_pte)) )
>          {
>              /* New mapping is superpage aligned, make it */
> -            pte = mfn_to_p2m_entry(*maddr >> PAGE_SHIFT, mattr, t);
> +            pte = mfn_to_p2m_entry(*maddr >> PAGE_SHIFT, mattr, t, a);
>              if ( level < 3 )
>                  pte.p2m.table = 0; /* Superpage entry */
>  
> @@ -770,7 +771,9 @@ static int apply_p2m_changes(struct domain *d,
>                       paddr_t end_gpaddr,
>                       paddr_t maddr,
>                       int mattr,
> -                     p2m_type_t t)
> +                     uint32_t mask,

What is this for? It is not used and you always pass 0 here and in a
later patch ~0.


> +                     p2m_type_t t,
> +                     p2m_access_t a)
>  {
>      int rc, ret;
>      struct p2m_domain *p2m = &d->arch.p2m;
> @@ -863,7 +866,7 @@ static int apply_p2m_changes(struct domain *d,
>                                    level, flush_pt, op,
>                                    start_gpaddr, end_gpaddr,
>                                    &addr, &maddr, &flush,
> -                                  mattr, t);
> +                                  mattr, t, a);
>              if ( ret < 0 ) { rc = ret ; goto out; }
>              count += ret;
>              /* L3 had better have done something! We cannot descend any 
> further */
> @@ -921,7 +924,7 @@ out:
>           */
>          apply_p2m_changes(d, REMOVE,
>                            start_gpaddr, addr + level_sizes[level], 
> orig_maddr,
> -                          mattr, p2m_invalid);
> +                          mattr, 0, p2m_invalid, d->arch.p2m.default_access);
>      }
>  
>      for ( level = P2M_ROOT_LEVEL; level < 4; level ++ )
> @@ -940,7 +943,8 @@ int p2m_populate_ram(struct domain *d,
>                       paddr_t end)
>  {
>      return apply_p2m_changes(d, ALLOCATE, start, end,
> -                             0, MATTR_MEM, p2m_ram_rw);
> +                             0, MATTR_MEM, 0, p2m_ram_rw,
> +                             d->arch.p2m.default_access);
>  }
>  
>  int map_mmio_regions(struct domain *d,
> @@ -952,7 +956,8 @@ int map_mmio_regions(struct domain *d,
>                               pfn_to_paddr(start_gfn),
>                               pfn_to_paddr(start_gfn + nr),
>                               pfn_to_paddr(mfn),
> -                             MATTR_DEV, p2m_mmio_direct);
> +                             MATTR_DEV, 0, p2m_mmio_direct,
> +                             d->arch.p2m.default_access);
>  }
>  
>  int unmap_mmio_regions(struct domain *d,
> @@ -964,7 +969,8 @@ int unmap_mmio_regions(struct domain *d,
>                               pfn_to_paddr(start_gfn),
>                               pfn_to_paddr(start_gfn + nr),
>                               pfn_to_paddr(mfn),
> -                             MATTR_DEV, p2m_invalid);
> +                             MATTR_DEV, 0, p2m_invalid,
> +                             d->arch.p2m.default_access);
>  }
>  
>  int guest_physmap_add_entry(struct domain *d,
> @@ -976,7 +982,8 @@ int guest_physmap_add_entry(struct domain *d,
>      return apply_p2m_changes(d, INSERT,
>                               pfn_to_paddr(gpfn),
>                               pfn_to_paddr(gpfn + (1 << page_order)),
> -                             pfn_to_paddr(mfn), MATTR_MEM, t);
> +                             pfn_to_paddr(mfn), MATTR_MEM, 0, t,
> +                             d->arch.p2m.default_access);
>  }
>  
>  void guest_physmap_remove_page(struct domain *d,
> @@ -986,7 +993,8 @@ void guest_physmap_remove_page(struct domain *d,
>      apply_p2m_changes(d, REMOVE,
>                        pfn_to_paddr(gpfn),
>                        pfn_to_paddr(gpfn + (1<<page_order)),
> -                      pfn_to_paddr(mfn), MATTR_MEM, p2m_invalid);
> +                      pfn_to_paddr(mfn), MATTR_MEM, 0, p2m_invalid,
> +                      d->arch.p2m.default_access);
>  }
>  
>  int p2m_alloc_table(struct domain *d)
> @@ -1090,6 +1098,8 @@ void p2m_teardown(struct domain *d)
>  
>      p2m_free_vmid(d);
>  
> +    radix_tree_destroy(&p2m->mem_access_settings, NULL);
> +
>      spin_unlock(&p2m->lock);
>  }
>  
> @@ -1115,6 +1125,10 @@ int p2m_init(struct domain *d)
>      p2m->max_mapped_gfn = 0;
>      p2m->lowest_mapped_gfn = ULONG_MAX;
>  
> +    p2m->default_access = p2m_access_rwx;
> +    p2m->mem_access_enabled = false;
> +    radix_tree_init(&p2m->mem_access_settings);
> +
>  err:
>      spin_unlock(&p2m->lock);
>  
> @@ -1129,7 +1143,8 @@ int relinquish_p2m_mapping(struct domain *d)
>                                pfn_to_paddr(p2m->lowest_mapped_gfn),
>                                pfn_to_paddr(p2m->max_mapped_gfn),
>                                pfn_to_paddr(INVALID_MFN),
> -                              MATTR_MEM, p2m_invalid);
> +                              MATTR_MEM, 0, p2m_invalid,
> +                              d->arch.p2m.default_access);
>  }
>  
>  int p2m_cache_flush(struct domain *d, xen_pfn_t start_mfn, xen_pfn_t end_mfn)
> @@ -1143,7 +1158,8 @@ int p2m_cache_flush(struct domain *d, xen_pfn_t 
> start_mfn, xen_pfn_t end_mfn)
>                               pfn_to_paddr(start_mfn),
>                               pfn_to_paddr(end_mfn),
>                               pfn_to_paddr(INVALID_MFN),
> -                             MATTR_MEM, p2m_invalid);
> +                             MATTR_MEM, 0, p2m_invalid,
> +                             d->arch.p2m.default_access);
>  }
>  
>  unsigned long gmfn_to_mfn(struct domain *d, unsigned long gpfn)
> diff --git a/xen/include/asm-arm/domain.h b/xen/include/asm-arm/domain.h
> index 9e0419e..f1a087e 100644
> --- a/xen/include/asm-arm/domain.h
> +++ b/xen/include/asm-arm/domain.h
> @@ -17,6 +17,7 @@ struct hvm_domain
>  {
>      uint64_t              params[HVM_NR_PARAMS];
>      struct hvm_iommu      iommu;
> +    bool_t                introspection_enabled;
>  }  __cacheline_aligned;
>  
>  #ifdef CONFIG_ARM_64
> diff --git a/xen/include/asm-arm/p2m.h b/xen/include/asm-arm/p2m.h
> index da36504..7583d9b 100644
> --- a/xen/include/asm-arm/p2m.h
> +++ b/xen/include/asm-arm/p2m.h
> @@ -2,8 +2,9 @@
>  #define _XEN_P2M_H
>  
>  #include <xen/mm.h>
> -
> +#include <xen/radix-tree.h>
>  #include <xen/p2m-common.h>
> +#include <public/memory.h>
>  
>  #define paddr_bits PADDR_BITS
>  
> @@ -48,6 +49,18 @@ struct p2m_domain {
>      /* If true, and an access fault comes in and there is no mem_event 
> listener,
>       * pause domain. Otherwise, remove access restrictions. */
>      bool_t access_required;
> +
> +    /* Defines if mem_access is in use for the domain. */
> +    bool_t mem_access_enabled;
> +
> +    /* Default P2M access type for each page in the the domain: new pages,
> +     * swapped in pages, cleared pages, and pages that are ambiguously
> +     * retyped get this access type. See definition of p2m_access_t. */
> +    p2m_access_t default_access;
> +
> +    /* Radix tree to store the p2m_access_t settings as the pte's don't have
> +     * enough available bits to store this information. */
> +    struct radix_tree_root mem_access_settings;
>  };
>  
>  /* List of possible type for each page in the p2m entry.
> @@ -217,6 +230,26 @@ static inline int get_page_and_type(struct page_info 
> *page,
>  /* get host p2m table */
>  #define p2m_get_hostp2m(d) (&(d)->arch.p2m)
>  
> +/* mem_event and mem_access are supported on any ARM guest */
> +static inline bool_t p2m_mem_access_sanity_check(struct domain *d)
> +{
> +    return 1;
> +}
> +
> +static inline bool_t p2m_mem_event_sanity_check(struct domain *d)
> +{
> +    return 1;
> +}
> +
> +/* Get access type for a pfn
> + * If pfn == -1ul, gets the default access type */
> +static inline
> +int p2m_get_mem_access(struct domain *d, unsigned long pfn,
> +                       xenmem_access_t *access)
> +{
> +    return -ENOSYS;
> +}
> +
>  #endif /* _XEN_P2M_H */
>  
>  /*
> diff --git a/xen/include/asm-arm/processor.h b/xen/include/asm-arm/processor.h
> index fcd26fb..cf7ab7c 100644
> --- a/xen/include/asm-arm/processor.h
> +++ b/xen/include/asm-arm/processor.h
> @@ -441,7 +441,7 @@ union hsr {
>      struct hsr_dabt {
>          unsigned long dfsc:6;  /* Data Fault Status Code */
>          unsigned long write:1; /* Write / not Read */
> -        unsigned long s1ptw:1; /* */
> +        unsigned long s1ptw:1; /* Stage 2 fault during stage 1 translation */
>          unsigned long cache:1; /* Cache Maintenance */
>          unsigned long eat:1;   /* External Abort Type */
>  #ifdef CONFIG_ARM_32
> -- 
> 2.1.4
> 

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