Re: [Qemu-devel] [Patch] Support translating Guest physical address to Host virtual address.

[Anthony Liguori <aliguori@linux.vnet.ibm.com>]

On 01/26/2010 09:25 PM, Zheng, Jiajia wrote:
> Add command p2v to translate Guest physical address to Host virtual address.
>    

For what purpose?

> Signed-off-by: Max Asbock<masbock@linux.vnet.ibm.com>
> 		Jiajia Zheng<jiajia.zheng@intel.com>
> ---
> diff --git a/monitor.c b/monitor.c
> index b33b01f..83d9ac7 100644
> --- a/monitor.c
> +++ b/monitor.c
> @@ -668,6 +668,11 @@ static void do_info_uuid(Monitor *mon, QObject **ret_data)
>       *ret_data = qobject_from_jsonf("{ 'UUID': %s }", uuid);
>   }
>
> +static void do_info_p2v(Monitor *mon)
> +{
> +    monitor_printf(mon, "p2v implemented\n");
> +}
>    

These should be implemented as QMP commands.

>   /* get the current CPU defined by the user */
>   static int mon_set_cpu(int cpu_index)
>   {
> @@ -2283,6 +2288,14 @@ static void do_inject_mce(Monitor *mon, const QDict *qdict)
>               break;
>           }
>   }
> +static void do_p2v(Monitor *mon, const QDict *qdict)
> +{
> +    target_long size = 4096;
> +    target_long addr = qdict_get_int(qdict, "addr");
> +
> +    monitor_printf(mon, "Guest physical address %p is mapped at host virtual address %p\n", (void *)addr, cpu_physical_memory_map( (target_phys_addr_t)addr, (target_phys_addr_t *)&size, 0));
>    

This isn't quite right.  It assumes TARGET_PAGE_SIZE is 4k which is 
certainly not always true.  It also assumes that 
cpu_physical_memory_map() something that has some meaning which isn't 
necessarily the case.  It could be a pointer to a bounce buffer.

Could you give an end-to-end description of how you expect this 
mechanism to be used so we can work out a more appropriate set of 
interfaces.  I assume this is MCE related.

Regards,

Anthony Liguori