Re: [PATCH -v2] Monitor command: pfa2hva, translate guest physical address to host virtual address

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

On 11/01/2010 11:09 AM, Marcelo Tosatti wrote:
> On Tue, Oct 26, 2010 at 10:39:48AM +0800, Huang Ying wrote:
>    
>> Author: Max Asbock<masbock@linux.vnet.ibm.com>
>>
>> Add command pfa2hva to translate guest physical address to host
>> virtual address.
>>
>> The pfa2hva command provides one step in a chain of translations from
>> guest virtual to guest physical to host virtual to host physical. Host
>> physical is then used to inject a machine check error. As a
>> consequence the HWPOISON code on the host and the MCE injection code
>> in qemu-kvm are exercised.
>>
>> v2:
>>
>> - Add QMP support
>>      
>
> Looks good to me. Anthony?
>    

The translation is not stable so this is really a bad interface.

It definitely shouldn't be a QMP command and I don't think it's 
generally useful enough that it should be a monitor command.

It's impossible to use correctly as a general interface.

I gave this feedback when it was initially submitted.

Regards,

Anthony Liguori

>> Signed-off-by: Max Asbock<masbock@linux.vnet.ibm.com>
>> Signed-off-by: Jiajia Zheng<jiajia.zheng@intel.com>
>> Signed-off-by: Huang Ying<ying.huang@intel.com>
>> ---
>>   hmp-commands.hx |   15 +++++++++++++++
>>   monitor.c       |   22 ++++++++++++++++++++++
>>   qmp-commands.hx |   27 +++++++++++++++++++++++++++
>>   3 files changed, 64 insertions(+)
>>
>> --- a/monitor.c
>> +++ b/monitor.c
>> @@ -2272,6 +2272,28 @@ static void do_inject_mce(Monitor *mon,
>>   }
>>   #endif
>>
>> +static void do_pfa2hva_print(Monitor *mon, const QObject *data)
>> +{
>> +    QInt *qint;
>> +
>> +    qint = qobject_to_qint(data);
>> +    monitor_printf(mon, "0x%lx\n", (unsigned long)qint->value);
>> +}
>> +
>> +static int do_pfa2hva(Monitor *mon, const QDict *qdict, QObject **ret_data)
>> +{
>> +    target_phys_addr_t paddr;
>> +    target_phys_addr_t size = TARGET_PAGE_SIZE;
>> +    void *vaddr;
>> +
>> +    paddr = qdict_get_int(qdict, "addr");
>> +    vaddr = cpu_physical_memory_map(paddr,&size, 0);
>> +    cpu_physical_memory_unmap(vaddr, size, 0, 0);
>> +    *ret_data = qobject_from_jsonf("%ld", (unsigned long)vaddr);
>> +
>> +    return 0;
>> +}
>> +
>>   static int do_getfd(Monitor *mon, const QDict *qdict, QObject **ret_data)
>>   {
>>       const char *fdname = qdict_get_str(qdict, "fdname");
>> --- a/hmp-commands.hx
>> +++ b/hmp-commands.hx
>> @@ -293,6 +293,21 @@ Start gdbserver session (default @var{po
>>   ETEXI
>>
>>       {
>> +        .name       = "pfa2hva",
>> +        .args_type  = "fmt:/,addr:l",
>> +        .params     = "/fmt addr",
>> +        .help       = "translate guest physical 'addr' to host virtual address",
>> +        .user_print = do_pfa2hva_print,
>> +        .mhandler.cmd_new = do_pfa2hva,
>> +    },
>> +
>> +STEXI
>> +@item pfa2hva @var{addr}
>> +@findex pfa2hva
>> +Translate guest physical @var{addr} to host virtual address.
>> +ETEXI
>> +
>> +    {
>>           .name       = "x",
>>           .args_type  = "fmt:/,addr:l",
>>           .params     = "/fmt addr",
>> --- a/qmp-commands.hx
>> +++ b/qmp-commands.hx
>> @@ -738,6 +738,33 @@ Example:
>>   EQMP
>>
>>       {
>> +        .name       = "pfa2hva",
>> +        .args_type  = "addr:l",
>> +        .params     = "addr",
>> +        .help       = "translate guest physical 'addr' to host virtual address",
>> +        .user_print = do_pfa2hva_print,
>> +        .mhandler.cmd_new = do_pfa2hva,
>> +    },
>> +
>> +SQMP
>> +pfa2hva
>> +---
>> +
>> +Translate guest physical 'addr' to host virtual address.
>> +
>> +Arguments:
>> +
>> +- "addr": the guest physical address
>> +
>> +Example:
>> +
>> +->  { "execute": "pfa2hva",
>> +		"arguments": { "addr": 196608 } }
>> +<- { "return": 139888084717568 }
>> +
>> +EQMP
>> +
>> +    {
>>           .name       = "qmp_capabilities",
>>           .args_type  = "",
>>           .params     = "",
>>
>>