Re: [Xen-devel] [PATCH for-4.5 v8 12/19] xen/arm: p2m changes for mem_access support

[Tamas K Lengyel <tamas.lengyel@xxxxxxxxxxxx>]

On Wed, Sep 24, 2014 at 4:40 PM, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:

On Tue, 2014-09-23 at 15:14 +0200, Tamas K Lengyel wrote:
> Add p2m_access_t to struct page_info and add necessary changes for
> page table construction routines to pass the default access information.
> We store the p2m_access_t info in page_info as the PTE lacks enough
> software programmable bits.

The last bit of this is now out of date.

Ack.

 

> diff --git a/xen/include/asm-arm/domain.h b/xen/include/asm-arm/domain.h
> index 787e93c..3d69152 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;

I've not found the user of this yet, but is it not somewhat redundant
with p2m->access_in_use?

It's used by mem_event memop for XEN_DOMCTL_MEM_EVENT_OP_ACCESS_DISABLE. I just added this one field to the hvm_domain for compat reasons instead of abstracting setting that value to 0 and adding an empty inline for ARM. This looked like less trouble.

 

>  }  __cacheline_aligned;
>
>  #ifdef CONFIG_ARM_64
> diff --git a/xen/include/asm-arm/p2m.h b/xen/include/asm-arm/p2m.h
> index 27225c4..dba0df5 100644
> --- a/xen/include/asm-arm/p2m.h
> +++ b/xen/include/asm-arm/p2m.h

> +/* Look up a GFN and take a reference count on the backing page. */
> +typedef unsigned int p2m_query_t;
> +#define P2M_ALLOC    (1u<<0)   /* Populate PoD and paged-out entries */
> +#define P2M_UNSHARE  (1u<<1)   /* Break CoW sharing */

Are the a result of something going wrong in a rebase? The comment here
refers to get_page_from_gfn which you've left behind, so it is out of
context now.

I don't think your other changes here require any of this to move, do
they?

Ack, these are just artifacts from the previous iteration.

 

> +    /* Defines if mem_access is in use for the domain to avoid uneccessary radix

"unnecessary"

Ack.

 

> +     * lookups. */
> +    bool_t access_in_use;

> @@ -77,6 +97,7 @@ void p2m_mem_event_emulate_check(struct domain *d,
>      /* Not supported on ARM. */
>  };
>
> +static inline
>  void p2m_enable_msr_exit_interception(struct domain *d)

I think this must belong in a previous patch which added this fn?

Ian.

Yes and has been since renamed and fixed.

Thanks!
Tamas

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