Re: [PATCH v3] x86/arm/mm: use gfn instead of pfn in p2m_get_mem_access/p2m_set_mem_access

[Razvan Cojocaru <rcojocaru@bitdefender.com>]

On 06/26/2015 06:17 PM, Vitaly Kuznetsov wrote:
> 'pfn' and 'start_pfn' are ambiguous, both these functions expect GFNs as input.
> 
> On x86 the interface of p2m_set_mem_access() in p2m.c doesn't match the
> declaration in p2m-common.h as 'pfn' is being used instead of 'start_pfn'.
> 
> On ARM both p2m_set_mem_access and p2m_get_mem_access interfaces don't match
> declarations from p2m-common.h: p2m_set_mem_access uses 'pfn' instead of
> 'start_pfn' and p2m_get_mem_access uses 'gpfn' instead of 'pfn'.
> 
> There is also an issue in p2m_get_mem_access on x86: 'gfn' parameter passed to
> gfn_lock/gfn_unlock is not defined. This code compiles only because of a
> coincidence: gfn_lock/gfn_unlock are currently macros which don't use their
> second argument.
> 
> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> ---
> Changes since v2:
> - Instead of adding start_ prefix on ARM remove it on x86 [Jan Beulich,
>   Ian Campbell, Razvan Cojocaru]
> 
> Changes since v1:
> - This patch is a successor of '[PATCH] x86/mm: use existing 'pfn' in
>   p2m_get_mem_access', instead of fixing gfn_lock/gfn_unlock arguments we do
>   s/pfn/gfn/g for both p2m_get_mem_access/p2m_set_mem_access [Andrew Cooper,
>   Jan Beulich]
> 
> P.S.
> - The patch was compile-tested on x86 only.
> ---
>  xen/arch/arm/p2m.c           | 12 ++++++------
>  xen/arch/x86/mm/p2m.c        | 24 ++++++++++++------------
>  xen/include/xen/p2m-common.h | 12 ++++++------
>  3 files changed, 24 insertions(+), 24 deletions(-)
> 
> diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> index 903fa3f..54c238c 100644
> --- a/xen/arch/arm/p2m.c
> +++ b/xen/arch/arm/p2m.c
> @@ -1709,9 +1709,9 @@ bool_t p2m_mem_access_check(paddr_t gpa, vaddr_t gla, const struct npfec npfec)
>  
>  /*
>   * Set access type for a region of pfns.
> - * If start_pfn == -1ul, sets the default access type.
> + * If gfn == -1ul, sets the default access type.
>   */
> -long p2m_set_mem_access(struct domain *d, unsigned long pfn, uint32_t nr,
> +long p2m_set_mem_access(struct domain *d, unsigned long gfn, uint32_t nr,
>                          uint32_t start, uint32_t mask, xenmem_access_t access)
>  {
>      struct p2m_domain *p2m = p2m_get_hostp2m(d);
> @@ -1752,14 +1752,14 @@ long p2m_set_mem_access(struct domain *d, unsigned long pfn, uint32_t nr,
>      p2m->mem_access_enabled = true;
>  
>      /* If request to set default access. */
> -    if ( pfn == ~0ul )
> +    if ( gfn == ~0ul )
>      {
>          p2m->default_access = a;
>          return 0;
>      }
>  
>      rc = apply_p2m_changes(d, MEMACCESS,
> -                           pfn_to_paddr(pfn+start), pfn_to_paddr(pfn+nr),
> +                           pfn_to_paddr(gfn + start), pfn_to_paddr(gfn + nr),
>                             0, MATTR_MEM, mask, 0, a);
>      if ( rc < 0 )
>          return rc;
> @@ -1769,14 +1769,14 @@ long p2m_set_mem_access(struct domain *d, unsigned long pfn, uint32_t nr,
>      return 0;
>  }
>  
> -int p2m_get_mem_access(struct domain *d, unsigned long gpfn,
> +int p2m_get_mem_access(struct domain *d, unsigned long gfn,
>                         xenmem_access_t *access)
>  {
>      int ret;
>      struct p2m_domain *p2m = p2m_get_hostp2m(d);
>  
>      spin_lock(&p2m->lock);
> -    ret = __p2m_get_mem_access(d, gpfn, access);
> +    ret = __p2m_get_mem_access(d, gfn, access);
>      spin_unlock(&p2m->lock);
>  
>      return ret;
> diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
> index 1fd1194..0d01f89 100644
> --- a/xen/arch/x86/mm/p2m.c
> +++ b/xen/arch/x86/mm/p2m.c
> @@ -1600,9 +1600,9 @@ bool_t p2m_mem_access_check(paddr_t gpa, unsigned long gla,
>      return (p2ma == p2m_access_n2rwx);
>  }
>  
> -/* Set access type for a region of pfns.
> - * If start_pfn == -1ul, sets the default access type */

This multiline comment does not follow the current coding style (please
see the first multiline comment of the patch for an example of proper
style: sentences end with '.', and lines with text never contain /* or */).

This is of course not something you've introduced, but it's something
that can be corrected while passing through there. Though, if nobody
else minds I wouldn't bump the patch version over it.

> -long p2m_set_mem_access(struct domain *d, unsigned long pfn, uint32_t nr,
> +/* Set access type for a region of gfns.
> + * If gfn == -1ul, sets the default access type */

Comment coding style.

> +long p2m_set_mem_access(struct domain *d, unsigned long gfn, uint32_t nr,
>                          uint32_t start, uint32_t mask, xenmem_access_t access)
>  {
>      struct p2m_domain *p2m = p2m_get_hostp2m(d);
> @@ -1639,17 +1639,17 @@ long p2m_set_mem_access(struct domain *d, unsigned long pfn, uint32_t nr,
>      }
>  
>      /* If request to set default access */
> -    if ( pfn == ~0ul )
> +    if ( gfn == ~0ul )
>      {
>          p2m->default_access = a;
>          return 0;
>      }
>  
>      p2m_lock(p2m);
> -    for ( pfn += start; nr > start; ++pfn )
> +    for ( gfn += start; nr > start; ++gfn )
>      {
> -        mfn = p2m->get_entry(p2m, pfn, &t, &_a, 0, NULL);
> -        rc = p2m->set_entry(p2m, pfn, mfn, PAGE_ORDER_4K, t, a);
> +        mfn = p2m->get_entry(p2m, gfn, &t, &_a, 0, NULL);
> +        rc = p2m->set_entry(p2m, gfn, mfn, PAGE_ORDER_4K, t, a);
>          if ( rc )
>              break;
>  
> @@ -1664,9 +1664,9 @@ long p2m_set_mem_access(struct domain *d, unsigned long pfn, uint32_t nr,
>      return rc;
>  }
>  
> -/* Get access type for a pfn
> - * If pfn == -1ul, gets the default access type */

Comment coding style.

> -int p2m_get_mem_access(struct domain *d, unsigned long pfn, 
> +/* Get access type for a gfn
> + * If gfn == -1ul, gets the default access type */

Comment coding style.

> +int p2m_get_mem_access(struct domain *d, unsigned long gfn,
>                         xenmem_access_t *access)
>  {
>      struct p2m_domain *p2m = p2m_get_hostp2m(d);
> @@ -1690,14 +1690,14 @@ int p2m_get_mem_access(struct domain *d, unsigned long pfn,
>      };
>  
>      /* If request to get default access */
> -    if ( pfn == ~0ull ) 
> +    if ( gfn == ~0ull )
>      {
>          *access = memaccess[p2m->default_access];
>          return 0;
>      }
>  
>      gfn_lock(p2m, gfn, 0);
> -    mfn = p2m->get_entry(p2m, pfn, &t, &a, 0, NULL);
> +    mfn = p2m->get_entry(p2m, gfn, &t, &a, 0, NULL);
>      gfn_unlock(p2m, gfn, 0);
>  
>      if ( mfn_x(mfn) == INVALID_MFN )
> diff --git a/xen/include/xen/p2m-common.h b/xen/include/xen/p2m-common.h
> index bd36826..1e7e583 100644
> --- a/xen/include/xen/p2m-common.h
> +++ b/xen/include/xen/p2m-common.h
> @@ -45,17 +45,17 @@ int unmap_mmio_regions(struct domain *d,
>                         unsigned long mfn);
>  
>  /*
> - * Set access type for a region of pfns.
> - * If start_pfn == -1ul, sets the default access type.
> + * Set access type for a region of gfns.
> + * If gfn == -1ul, sets the default access type.
>   */
> -long p2m_set_mem_access(struct domain *d, unsigned long start_pfn, uint32_t nr,
> +long p2m_set_mem_access(struct domain *d, unsigned long gfn, uint32_t nr,
>                          uint32_t start, uint32_t mask, xenmem_access_t access);
>  
>  /*
> - * Get access type for a pfn.
> - * If pfn == -1ul, gets the default access type.
> + * Get access type for a gfn.
> + * If gfn == -1ul, gets the default access type.
>   */
> -int p2m_get_mem_access(struct domain *d, unsigned long pfn,
> +int p2m_get_mem_access(struct domain *d, unsigned long gfn,
>                         xenmem_access_t *access);
>  
>  #endif /* _XEN_P2M_COMMON_H */

Other than the multiline comments coding style,

Reviewed-by: Razvan Cojocaru <rcojocaru@bitdefender.com>


Cheers,
Razvan