Re: [Xen-devel] [PATCH v3 23/38] arm/p2m: Cosmetic fixes -- __p2m_get_mem_access

[Julien Grall <julien.grall@xxxxxxx>]

Hello Sergej,

On 16/08/2016 23:16, Sergej Proskurin wrote:
> This commit extends the function prototypes of the functions:
> * __p2m_get_mem_access
> * p2m_mem_access_check_and_get_page
>
> We extend the function prototype of "__p2m_get_mem_access" to hold an
> argument of type "struct p2m_domain*", as we need to distinguish between
> the host's p2m and different altp2m views. While doing so, we needed to
> extend the function's prototype of "p2m_mem_access_check_and_get_page"
> to hold an argument of type "struct vcpu*".
Please details in the commit message why it is necessary to pass a 
"struct vcpu *" to p2m_mem_access_check_and_get_page.
Regards,

> Signed-off-by: Sergej Proskurin <proskurin@xxxxxxxxxxxxx>
> ---
> Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> Cc: Julien Grall <julien.grall@xxxxxxx>
> ---
> v3: Changed the parameter of "p2m_mem_access_check_and_get_page"
>     from "struct p2m_domain*" to "struct vcpu*".
> ---
>  xen/arch/arm/p2m.c | 15 +++++++--------
>  1 file changed, 7 insertions(+), 8 deletions(-)
>
> diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> index 06f7eb8..5819ae0 100644
> --- a/xen/arch/arm/p2m.c
> +++ b/xen/arch/arm/p2m.c
> @@ -606,10 +606,9 @@ static int p2m_create_table(struct p2m_domain *p2m, lpae_t 
> *entry)
>      return 0;
>  }
>
> -static int __p2m_get_mem_access(struct domain *d, gfn_t gfn,
> +static int __p2m_get_mem_access(struct p2m_domain *p2m, gfn_t gfn,
>                                  xenmem_access_t *access)
>  {
> -    struct p2m_domain *p2m = p2m_get_hostp2m(d);
>      void *i;
>      unsigned int index;
>
> @@ -1471,7 +1470,7 @@ mfn_t gfn_to_mfn(struct domain *d, gfn_t gfn)
>   * we indeed found a conflicting mem_access setting.
>   */
>  static struct page_info*
> -p2m_mem_access_check_and_get_page(vaddr_t gva, unsigned long flag)
> +p2m_mem_access_check_and_get_page(struct vcpu *v, vaddr_t gva, unsigned long 
> flag)
>  {
>      long rc;
>      paddr_t ipa;
> @@ -1480,7 +1479,7 @@ p2m_mem_access_check_and_get_page(vaddr_t gva, unsigned 
> long flag)
>      xenmem_access_t xma;
>      p2m_type_t t;
>      struct page_info *page = NULL;
> -    struct p2m_domain *p2m = p2m_get_hostp2m(current->domain);
> +    struct p2m_domain *p2m = p2m_get_hostp2m(v->domain);
>
>      rc = gva_to_ipa(gva, &ipa, flag);
>      if ( rc < 0 )
> @@ -1492,7 +1491,7 @@ p2m_mem_access_check_and_get_page(vaddr_t gva, unsigned 
> long flag)
>       * We do this first as this is faster in the default case when no
>       * permission is set on the page.
>       */
> -    rc = __p2m_get_mem_access(current->domain, gfn, &xma);
> +    rc = __p2m_get_mem_access(p2m, gfn, &xma);
>      if ( rc < 0 )
>          goto err;
>
> @@ -1556,7 +1555,7 @@ p2m_mem_access_check_and_get_page(vaddr_t gva, unsigned 
> long flag)
>
>      page = mfn_to_page(mfn_x(mfn));
>
> -    if ( unlikely(!get_page(page, current->domain)) )
> +    if ( unlikely(!get_page(page, v->domain)) )
>          page = NULL;
>
>  err:
> @@ -1614,7 +1613,7 @@ struct page_info *get_page_from_gva(struct vcpu *v, 
> vaddr_t va,
>
>  err:
>      if ( !page && p2m->mem_access_enabled )
> -        page = p2m_mem_access_check_and_get_page(va, flags);
> +        page = p2m_mem_access_check_and_get_page(v, va, flags);
>
>      p2m_read_unlock(p2m);
>
> @@ -1927,7 +1926,7 @@ int p2m_get_mem_access(struct domain *d, gfn_t gfn,
>      struct p2m_domain *p2m = p2m_get_hostp2m(d);
>
>      p2m_read_lock(p2m);
> -    ret = __p2m_get_mem_access(d, gfn, access);
> +    ret = __p2m_get_mem_access(p2m, gfn, access);
>      p2m_read_unlock(p2m);
>
>      return ret;
--
Julien Grall

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