Re: [Xen-devel] [PATCH v2 1/8] xen: move XENMAPSPACE_grant_table code into grant_table.c

[Juergen Gross <jgross@xxxxxxxx>]

On 06/09/17 10:34, Paul Durrant wrote:
>> -----Original Message-----
>> From: Xen-devel [mailto:xen-devel-bounces@xxxxxxxxxxxxx] On Behalf Of
>> Juergen Gross
>> Sent: 06 September 2017 09:26
>> To: xen-devel@xxxxxxxxxxxxx
>> Cc: Juergen Gross <jgross@xxxxxxxx>; sstabellini@xxxxxxxxxx; Wei Liu
>> <wei.liu2@xxxxxxxxxx>; George Dunlap <George.Dunlap@xxxxxxxxxx>;
>> Andrew Cooper <Andrew.Cooper3@xxxxxxxxxx>; Ian Jackson
>> <Ian.Jackson@xxxxxxxxxx>; Tim (Xen.org) <tim@xxxxxxx>;
>> jbeulich@xxxxxxxx
>> Subject: [Xen-devel] [PATCH v2 1/8] xen: move XENMAPSPACE_grant_table
>> code into grant_table.c
>>
>> The x86 and arm versions of XENMAPSPACE_grant_table handling are nearly
>> identical. Move the code into a function in grant_table.c and add an
>> architecture dependant hook to handle the differences.
>>
>> This at once fixes a bug in the arm code which didn't unlock the grant
>> table in error case.
> 
> You also move to greater use of type-safe mfn in x86 
> xenmem_add_to_physmap_one(), which is a good thing :-). Might be worth a 
> mention in the commit comment though.

Yeah. And I should remove the paragraph with the error on ARM, as it
is no longer true.


Juergen

> 
> Reviewed-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
> 
>>
>> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
>> ---
>> V2:
>> - rebased to staging
>> ---
>>  xen/arch/arm/mm.c                 | 36 ++++------------------------------
>>  xen/arch/x86/mm.c                 | 41 
>> ++++++++++-----------------------------
>>  xen/common/grant_table.c          | 38
>> ++++++++++++++++++++++++++++++++++++
>>  xen/include/asm-arm/grant_table.h |  7 +++++++
>>  xen/include/asm-x86/grant_table.h |  5 +++++
>>  xen/include/xen/grant_table.h     |  3 +++
>>  6 files changed, 67 insertions(+), 63 deletions(-)
>>
>> diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
>> index b39677eac9..3db0e3bdea 100644
>> --- a/xen/arch/arm/mm.c
>> +++ b/xen/arch/arm/mm.c
>> @@ -1229,39 +1229,11 @@ int xenmem_add_to_physmap_one(
>>      switch ( space )
>>      {
>>      case XENMAPSPACE_grant_table:
>> -        grant_write_lock(d->grant_table);
>> -
>> -        if ( d->grant_table->gt_version == 0 )
>> -            d->grant_table->gt_version = 1;
>> -
>> -        if ( d->grant_table->gt_version == 2 &&
>> -                (idx & XENMAPIDX_grant_table_status) )
>> -        {
>> -            idx &= ~XENMAPIDX_grant_table_status;
>> -            if ( idx < nr_status_frames(d->grant_table) )
>> -                mfn = virt_to_mfn(d->grant_table->status[idx]);
>> -        }
>> -        else
>> -        {
>> -            if ( (idx >= nr_grant_frames(d->grant_table)) &&
>> -                 (idx < max_grant_frames) )
>> -                gnttab_grow_table(d, idx + 1);
>> -
>> -            if ( idx < nr_grant_frames(d->grant_table) )
>> -                mfn = virt_to_mfn(d->grant_table->shared_raw[idx]);
>> -        }
>> -
>> -        if ( !mfn_eq(mfn, INVALID_MFN) )
>> -        {
>> -            d->arch.grant_table_gfn[idx] = gfn;
>> -
>> -            t = p2m_ram_rw;
>> -        }
>> -
>> -        grant_write_unlock(d->grant_table);
>> +        rc = gnttab_map_frame(d, idx, gfn, &mfn);
>> +        if ( rc )
>> +            return rc;
>>
>> -        if ( mfn_eq(mfn, INVALID_MFN) )
>> -            return -EINVAL;
>> +        t = p2m_ram_rw;
>>
>>          break;
>>      case XENMAPSPACE_shared_info:
>> diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
>> index e5a029c9be..3d899e4a8e 100644
>> --- a/xen/arch/x86/mm.c
>> +++ b/xen/arch/x86/mm.c
>> @@ -4631,40 +4631,19 @@ int xenmem_add_to_physmap_one(
>>  {
>>      struct page_info *page = NULL;
>>      unsigned long gfn = 0; /* gcc ... */
>> -    unsigned long prev_mfn, mfn = 0, old_gpfn;
>> +    unsigned long prev_mfn, old_gpfn;
>>      int rc = 0;
>> +    mfn_t mfn = INVALID_MFN;
>>      p2m_type_t p2mt;
>>
>>      switch ( space )
>>      {
>>          case XENMAPSPACE_shared_info:
>>              if ( idx == 0 )
>> -                mfn = virt_to_mfn(d->shared_info);
>> +                mfn = _mfn(virt_to_mfn(d->shared_info));
>>              break;
>>          case XENMAPSPACE_grant_table:
>> -            grant_write_lock(d->grant_table);
>> -
>> -            if ( d->grant_table->gt_version == 0 )
>> -                d->grant_table->gt_version = 1;
>> -
>> -            if ( d->grant_table->gt_version == 2 &&
>> -                 (idx & XENMAPIDX_grant_table_status) )
>> -            {
>> -                idx &= ~XENMAPIDX_grant_table_status;
>> -                if ( idx < nr_status_frames(d->grant_table) )
>> -                    mfn = virt_to_mfn(d->grant_table->status[idx]);
>> -            }
>> -            else
>> -            {
>> -                if ( (idx >= nr_grant_frames(d->grant_table)) &&
>> -                     (idx < max_grant_frames) )
>> -                    gnttab_grow_table(d, idx + 1);
>> -
>> -                if ( idx < nr_grant_frames(d->grant_table) )
>> -                    mfn = virt_to_mfn(d->grant_table->shared_raw[idx]);
>> -            }
>> -
>> -            grant_write_unlock(d->grant_table);
>> +            gnttab_map_frame(d, idx, gpfn, &mfn);
>>              break;
>>          case XENMAPSPACE_gmfn_range:
>>          case XENMAPSPACE_gmfn:
>> @@ -4681,8 +4660,8 @@ int xenmem_add_to_physmap_one(
>>              }
>>              if ( !get_page_from_mfn(_mfn(idx), d) )
>>                  break;
>> -            mfn = idx;
>> -            page = mfn_to_page(_mfn(mfn));
>> +            mfn = _mfn(idx);
>> +            page = mfn_to_page(mfn);
>>              break;
>>          }
>>          case XENMAPSPACE_gmfn_foreign:
>> @@ -4691,7 +4670,7 @@ int xenmem_add_to_physmap_one(
>>              break;
>>      }
>>
>> -    if ( !paging_mode_translate(d) || (mfn == 0) )
>> +    if ( !paging_mode_translate(d) || mfn_eq(mfn, INVALID_MFN) )
>>      {
>>          rc = -EINVAL;
>>          goto put_both;
>> @@ -4715,16 +4694,16 @@ int xenmem_add_to_physmap_one(
>>          goto put_both;
>>
>>      /* Unmap from old location, if any. */
>> -    old_gpfn = get_gpfn_from_mfn(mfn);
>> +    old_gpfn = get_gpfn_from_mfn(mfn_x(mfn));
>>      ASSERT( old_gpfn != SHARED_M2P_ENTRY );
>>      if ( space == XENMAPSPACE_gmfn || space ==
>> XENMAPSPACE_gmfn_range )
>>          ASSERT( old_gpfn == gfn );
>>      if ( old_gpfn != INVALID_M2P_ENTRY )
>> -        rc = guest_physmap_remove_page(d, _gfn(old_gpfn), _mfn(mfn),
>> PAGE_ORDER_4K);
>> +        rc = guest_physmap_remove_page(d, _gfn(old_gpfn), mfn,
>> PAGE_ORDER_4K);
>>
>>      /* Map at new location. */
>>      if ( !rc )
>> -        rc = guest_physmap_add_page(d, gpfn, _mfn(mfn), PAGE_ORDER_4K);
>> +        rc = guest_physmap_add_page(d, gpfn, mfn, PAGE_ORDER_4K);
>>
>>   put_both:
>>      /* In the XENMAPSPACE_gmfn, we took a ref of the gfn at the top */
>> diff --git a/xen/common/grant_table.c b/xen/common/grant_table.c
>> index fb3859ce8e..4c2e9e40a5 100644
>> --- a/xen/common/grant_table.c
>> +++ b/xen/common/grant_table.c
>> @@ -3607,6 +3607,44 @@ int mem_sharing_gref_to_gfn(struct grant_table
>> *gt, grant_ref_t ref,
>>  }
>>  #endif
>>
>> +int gnttab_map_frame(struct domain *d, unsigned long idx, gfn_t gfn,
>> +                     mfn_t *mfn)
>> +{
>> +    int rc = 0;
>> +    struct grant_table *gt = d->grant_table;
>> +
>> +    grant_write_lock(gt);
>> +
>> +    if ( gt->gt_version == 0 )
>> +        gt->gt_version = 1;
>> +
>> +    if ( gt->gt_version == 2 &&
>> +         (idx & XENMAPIDX_grant_table_status) )
>> +    {
>> +        idx &= ~XENMAPIDX_grant_table_status;
>> +        if ( idx < nr_status_frames(gt) )
>> +            *mfn = _mfn(virt_to_mfn(gt->status[idx]));
>> +        else
>> +            rc = -EINVAL;
>> +    }
>> +    else
>> +    {
>> +        if ( (idx >= nr_grant_frames(gt)) && (idx < max_grant_frames) )
>> +            gnttab_grow_table(d, idx + 1);
>> +
>> +        if ( idx < nr_grant_frames(gt) )
>> +            *mfn = _mfn(virt_to_mfn(gt->shared_raw[idx]));
>> +        else
>> +            rc = -EINVAL;
>> +    }
>> +
>> +    gnttab_set_frame_gfn(d, idx, gfn);
>> +
>> +    grant_write_unlock(gt);
>> +
>> +    return rc;
>> +}
>> +
>>  static void gnttab_usage_print(struct domain *rd)
>>  {
>>      int first = 1;
>> diff --git a/xen/include/asm-arm/grant_table.h b/xen/include/asm-
>> arm/grant_table.h
>> index bc4d61a940..0a248a765a 100644
>> --- a/xen/include/asm-arm/grant_table.h
>> +++ b/xen/include/asm-arm/grant_table.h
>> @@ -2,6 +2,7 @@
>>  #define __ASM_GRANT_TABLE_H__
>>
>>  #include <xen/grant_table.h>
>> +#include <xen/sched.h>
>>
>>  #define INITIAL_NR_GRANT_FRAMES 4
>>
>> @@ -21,6 +22,12 @@ static inline int replace_grant_supported(void)
>>      return 1;
>>  }
>>
>> +static inline void gnttab_set_frame_gfn(struct domain *d, unsigned long
>> idx,
>> +                                        gfn_t gfn)
>> +{
>> +    d->arch.grant_table_gfn[idx] = gfn;
>> +}
>> +
>>  #define gnttab_create_shared_page(d, t, i)                               \
>>      do {                                                                 \
>>          share_xen_page_with_guest(                                       \
>> diff --git a/xen/include/asm-x86/grant_table.h b/xen/include/asm-
>> x86/grant_table.h
>> index 33b2f88b96..c865999a33 100644
>> --- a/xen/include/asm-x86/grant_table.h
>> +++ b/xen/include/asm-x86/grant_table.h
>> @@ -75,6 +75,11 @@ static inline void gnttab_clear_flag(unsigned int nr,
>> uint16_t *st)
>>      asm volatile ("lock btrw %w1,%0" : "=m" (*st) : "Ir" (nr), "m" (*st));
>>  }
>>
>> +static inline void gnttab_set_frame_gfn(struct domain *d, unsigned long
>> idx,
>> +                                        gfn_t gfn)
>> +{
>> +}
>> +
>>  /* Foreign mappings of HHVM-guest pages do not modify the type count. */
>>  #define gnttab_host_mapping_get_page_type(ro, ld, rd)   \
>>      (!(ro) && (((ld) == (rd)) || !paging_mode_external(rd)))
>> diff --git a/xen/include/xen/grant_table.h b/xen/include/xen/grant_table.h
>> index af269a108d..43ec6c4d80 100644
>> --- a/xen/include/xen/grant_table.h
>> +++ b/xen/include/xen/grant_table.h
>> @@ -136,4 +136,7 @@ static inline unsigned int grant_to_status_frames(int
>> grant_frames)
>>  int mem_sharing_gref_to_gfn(struct grant_table *gt, grant_ref_t ref,
>>                              gfn_t *gfn, uint16_t *status);
>>
>> +int gnttab_map_frame(struct domain *d, unsigned long idx, gfn_t gfn,
>> +                     mfn_t *mfn);
>> +
>>  #endif /* __XEN_GRANT_TABLE_H__ */
>> --
>> 2.12.3
>>
>>
>> _______________________________________________
>> Xen-devel mailing list
>> Xen-devel@xxxxxxxxxxxxx
>> https://lists.xen.org/xen-devel


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