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Re: [Xen-devel] [PATCH 11/22] xen/arm: p2m: Find the memory attributes based on the p2m type



On Wed, 27 Jul 2016, Julien Grall wrote:
> Hi,
> 
> On 20/07/16 17:10, Julien Grall wrote:
> > Currently, mfn_to_p2m_entry is relying on the caller to provide the
> > correct memory attribute and will deduce the sharability based on it.
> > 
> > Some of the callers, such as p2m_create_table, are using same memory
> > attribute regardless the underlying p2m type. For instance, this will
> > lead to use change the memory attribute from MATTR_DEV to MATTR_MEM when
> > a MMIO superpage is shattered.
> > 
> > Furthermore, it makes more difficult to support different shareability
> > with the same memory attribute.
> > 
> > All the memory attributes could be deduced via the p2m type. This will
> > simplify the code by dropping one parameter.
> 
> I just noticed that I forgot to add my Signed-off-by. Stefano, can you add my
> Signed-off-by while committing?

I could, but given that you need to resend some of the patches anyway,
it might be easier for me to wait for the next version.

 
> > ---
> >     I am not sure whether p2m_direct_mmio_c (cacheable MMIO) should use
> >     the outer-shareability or inner-shareability. Any opinions?
> > ---
> >  xen/arch/arm/p2m.c | 55
> > ++++++++++++++++++++++++------------------------------
> >  1 file changed, 24 insertions(+), 31 deletions(-)
> > 
> > diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> > index 999de2b..2f50b4f 100644
> > --- a/xen/arch/arm/p2m.c
> > +++ b/xen/arch/arm/p2m.c
> > @@ -325,8 +325,7 @@ static void p2m_set_permission(lpae_t *e, p2m_type_t t,
> > p2m_access_t a)
> >      }
> >  }
> > 
> > -static lpae_t mfn_to_p2m_entry(mfn_t mfn, unsigned int mattr,
> > -                               p2m_type_t t, p2m_access_t a)
> > +static lpae_t mfn_to_p2m_entry(mfn_t mfn, p2m_type_t t, p2m_access_t a)
> >  {
> >      /*
> >       * sh, xn and write bit will be defined in the following switches
> > @@ -335,7 +334,6 @@ static lpae_t mfn_to_p2m_entry(mfn_t mfn, unsigned int
> > mattr,
> >      lpae_t e = (lpae_t) {
> >          .p2m.af = 1,
> >          .p2m.read = 1,
> > -        .p2m.mattr = mattr,
> >          .p2m.table = 1,
> >          .p2m.valid = 1,
> >          .p2m.type = t,
> > @@ -343,18 +341,21 @@ static lpae_t mfn_to_p2m_entry(mfn_t mfn, unsigned int
> > mattr,
> > 
> >      BUILD_BUG_ON(p2m_max_real_type > (1 << 4));
> > 
> > -    switch (mattr)
> > +    switch ( t )
> >      {
> > -    case MATTR_MEM:
> > -        e.p2m.sh = LPAE_SH_INNER;
> > +    case p2m_mmio_direct_nc:
> > +        e.p2m.mattr = MATTR_DEV;
> > +        e.p2m.sh = LPAE_SH_OUTER;
> >          break;
> > 
> > -    case MATTR_DEV:
> > +    case p2m_mmio_direct_c:
> > +        e.p2m.mattr = MATTR_MEM;
> >          e.p2m.sh = LPAE_SH_OUTER;
> >          break;
> > +
> >      default:
> > -        BUG();
> > -        break;
> > +        e.p2m.mattr = MATTR_MEM;
> > +        e.p2m.sh = LPAE_SH_INNER;
> >      }
> > 
> >      p2m_set_permission(&e, t, a);
> > @@ -421,7 +422,7 @@ static int p2m_create_table(struct domain *d, lpae_t
> > *entry,
> >           */
> >           for ( i=0 ; i < LPAE_ENTRIES; i++ )
> >           {
> > -             pte = mfn_to_p2m_entry(mfn, MATTR_MEM, t,
> > p2m->default_access);
> > +             pte = mfn_to_p2m_entry(mfn, t, p2m->default_access);
> > 
> >               mfn = mfn_add(mfn, 1UL << (level_shift - LPAE_SHIFT));
> > 
> > @@ -445,7 +446,7 @@ static int p2m_create_table(struct domain *d, lpae_t
> > *entry,
> > 
> >      unmap_domain_page(p);
> > 
> > -    pte = mfn_to_p2m_entry(_mfn(page_to_mfn(page)), MATTR_MEM, p2m_invalid,
> > +    pte = mfn_to_p2m_entry(_mfn(page_to_mfn(page)), p2m_invalid,
> >                             p2m->default_access);
> > 
> >      p2m_write_pte(entry, pte, flush_cache);
> > @@ -666,7 +667,6 @@ static int apply_one_level(struct domain *d,
> >                             paddr_t *addr,
> >                             paddr_t *maddr,
> >                             bool_t *flush,
> > -                           int mattr,
> >                             p2m_type_t t,
> >                             p2m_access_t a)
> >  {
> > @@ -695,7 +695,7 @@ static int apply_one_level(struct domain *d,
> >                  return rc;
> > 
> >              /* New mapping is superpage aligned, make it */
> > -            pte = mfn_to_p2m_entry(_mfn(*maddr >> PAGE_SHIFT), mattr, t,
> > a);
> > +            pte = mfn_to_p2m_entry(_mfn(*maddr >> PAGE_SHIFT), t, a);
> >              if ( level < 3 )
> >                  pte.p2m.table = 0; /* Superpage entry */
> > 
> > @@ -915,7 +915,6 @@ static int apply_p2m_changes(struct domain *d,
> >                       gfn_t sgfn,
> >                       unsigned long nr,
> >                       mfn_t smfn,
> > -                     int mattr,
> >                       uint32_t mask,
> >                       p2m_type_t t,
> >                       p2m_access_t a)
> > @@ -1054,7 +1053,7 @@ static int apply_p2m_changes(struct domain *d,
> >                                    level, flush_pt, op,
> >                                    start_gpaddr, end_gpaddr,
> >                                    &addr, &maddr, &flush,
> > -                                  mattr, t, a);
> > +                                  t, a);
> >              if ( ret < 0 ) { rc = ret ; goto out; }
> >              count += ret;
> > 
> > @@ -1163,7 +1162,7 @@ out:
> >           * mapping.
> >           */
> >          apply_p2m_changes(d, REMOVE, sgfn, gfn - gfn_x(sgfn), smfn,
> > -                          mattr, 0, p2m_invalid,
> > d->arch.p2m.default_access);
> > +                          0, p2m_invalid, d->arch.p2m.default_access);
> >      }
> > 
> >      return rc;
> > @@ -1173,10 +1172,10 @@ static inline int p2m_insert_mapping(struct domain
> > *d,
> >                                       gfn_t start_gfn,
> >                                       unsigned long nr,
> >                                       mfn_t mfn,
> > -                                     int mattr, p2m_type_t t)
> > +                                     p2m_type_t t)
> >  {
> >      return apply_p2m_changes(d, INSERT, start_gfn, nr, mfn,
> > -                             mattr, 0, t, d->arch.p2m.default_access);
> > +                             0, t, d->arch.p2m.default_access);
> >  }
> > 
> >  static inline int p2m_remove_mapping(struct domain *d,
> > @@ -1186,8 +1185,7 @@ static inline int p2m_remove_mapping(struct domain *d,
> >  {
> >      return apply_p2m_changes(d, REMOVE, start_gfn, nr, mfn,
> >                               /* arguments below not used when removing
> > mapping */
> > -                             MATTR_MEM, 0, p2m_invalid,
> > -                             d->arch.p2m.default_access);
> > +                             0, p2m_invalid, d->arch.p2m.default_access);
> >  }
> > 
> >  int map_regions_rw_cache(struct domain *d,
> > @@ -1195,8 +1193,7 @@ int map_regions_rw_cache(struct domain *d,
> >                           unsigned long nr,
> >                           mfn_t mfn)
> >  {
> > -    return p2m_insert_mapping(d, gfn, nr, mfn,
> > -                              MATTR_MEM, p2m_mmio_direct_c);
> > +    return p2m_insert_mapping(d, gfn, nr, mfn, p2m_mmio_direct_c);
> >  }
> > 
> >  int unmap_regions_rw_cache(struct domain *d,
> > @@ -1212,8 +1209,7 @@ int map_mmio_regions(struct domain *d,
> >                       unsigned long nr,
> >                       mfn_t mfn)
> >  {
> > -    return p2m_insert_mapping(d, start_gfn, nr, mfn,
> > -                              MATTR_DEV, p2m_mmio_direct_nc);
> > +    return p2m_insert_mapping(d, start_gfn, nr, mfn, p2m_mmio_direct_nc);
> >  }
> > 
> >  int unmap_mmio_regions(struct domain *d,
> > @@ -1251,8 +1247,7 @@ int guest_physmap_add_entry(struct domain *d,
> >                              unsigned long page_order,
> >                              p2m_type_t t)
> >  {
> > -    return p2m_insert_mapping(d, gfn, (1 << page_order), mfn,
> > -                              MATTR_MEM, t);
> > +    return p2m_insert_mapping(d, gfn, (1 << page_order), mfn, t);
> >  }
> > 
> >  void guest_physmap_remove_page(struct domain *d,
> > @@ -1412,7 +1407,7 @@ int relinquish_p2m_mapping(struct domain *d)
> >      nr = gfn_x(p2m->max_mapped_gfn) - gfn_x(p2m->lowest_mapped_gfn);
> > 
> >      return apply_p2m_changes(d, RELINQUISH, p2m->lowest_mapped_gfn, nr,
> > -                             INVALID_MFN, MATTR_MEM, 0, p2m_invalid,
> > +                             INVALID_MFN, 0, p2m_invalid,
> >                               d->arch.p2m.default_access);
> >  }
> > 
> > @@ -1425,8 +1420,7 @@ int p2m_cache_flush(struct domain *d, gfn_t start,
> > unsigned long nr)
> >      end = gfn_min(end, p2m->max_mapped_gfn);
> > 
> >      return apply_p2m_changes(d, CACHEFLUSH, start, nr, INVALID_MFN,
> > -                             MATTR_MEM, 0, p2m_invalid,
> > -                             d->arch.p2m.default_access);
> > +                             0, p2m_invalid, d->arch.p2m.default_access);
> >  }
> > 
> >  mfn_t gfn_to_mfn(struct domain *d, gfn_t gfn)
> > @@ -1827,8 +1821,7 @@ long p2m_set_mem_access(struct domain *d, gfn_t gfn,
> > uint32_t nr,
> >      }
> > 
> >      rc = apply_p2m_changes(d, MEMACCESS, gfn_add(gfn, start),
> > -                           (nr - start), INVALID_MFN,
> > -                           MATTR_MEM, mask, 0, a);
> > +                           (nr - start), INVALID_MFN, mask, 0, a);
> >      if ( rc < 0 )
> >          return rc;
> >      else if ( rc > 0 )
> > 
> 
> -- 
> Julien Grall
> 

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