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Re: [Xen-devel] [PATCH for-4.12] x86/vpmu: Improve documentation and parsing for vpmu=


  • To: Jan Beulich <JBeulich@xxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
  • From: Juergen Gross <jgross@xxxxxxxx>
  • Date: Mon, 4 Feb 2019 17:10:00 +0100
  • Autocrypt: addr=jgross@xxxxxxxx; prefer-encrypt=mutual; keydata= xsBNBFOMcBYBCACgGjqjoGvbEouQZw/ToiBg9W98AlM2QHV+iNHsEs7kxWhKMjrioyspZKOB ycWxw3ie3j9uvg9EOB3aN4xiTv4qbnGiTr3oJhkB1gsb6ToJQZ8uxGq2kaV2KL9650I1SJve dYm8Of8Zd621lSmoKOwlNClALZNew72NjJLEzTalU1OdT7/i1TXkH09XSSI8mEQ/ouNcMvIJ NwQpd369y9bfIhWUiVXEK7MlRgUG6MvIj6Y3Am/BBLUVbDa4+gmzDC9ezlZkTZG2t14zWPvx XP3FAp2pkW0xqG7/377qptDmrk42GlSKN4z76ELnLxussxc7I2hx18NUcbP8+uty4bMxABEB AAHNHkp1ZXJnZW4gR3Jvc3MgPGpncm9zc0BzdXNlLmRlPsLAeQQTAQIAIwUCU4xw6wIbAwcL CQgHAwIBBhUIAgkKCwQWAgMBAh4BAheAAAoJELDendYovxMvi4UH/Ri+OXlObzqMANruTd4N zmVBAZgx1VW6jLc8JZjQuJPSsd/a+bNr3BZeLV6lu4Pf1Yl2Log129EX1KWYiFFvPbIiq5M5 kOXTO8Eas4CaScCvAZ9jCMQCgK3pFqYgirwTgfwnPtxFxO/F3ZcS8jovza5khkSKL9JGq8Nk czDTruQ/oy0WUHdUr9uwEfiD9yPFOGqp4S6cISuzBMvaAiC5YGdUGXuPZKXLpnGSjkZswUzY d9BVSitRL5ldsQCg6GhDoEAeIhUC4SQnT9SOWkoDOSFRXZ+7+WIBGLiWMd+yKDdRG5RyP/8f 3tgGiB6cyuYfPDRGsELGjUaTUq3H2xZgIPfOwE0EU4xwFgEIAMsx+gDjgzAY4H1hPVXgoLK8 B93sTQFN9oC6tsb46VpxyLPfJ3T1A6Z6MVkLoCejKTJ3K9MUsBZhxIJ0hIyvzwI6aYJsnOew cCiCN7FeKJ/oA1RSUemPGUcIJwQuZlTOiY0OcQ5PFkV5YxMUX1F/aTYXROXgTmSaw0aC1Jpo w7Ss1mg4SIP/tR88/d1+HwkJDVW1RSxC1PWzGizwRv8eauImGdpNnseneO2BNWRXTJumAWDD pYxpGSsGHXuZXTPZqOOZpsHtInFyi5KRHSFyk2Xigzvh3b9WqhbgHHHE4PUVw0I5sIQt8hJq 5nH5dPqz4ITtCL9zjiJsExHuHKN3NZsAEQEAAcLAXwQYAQIACQUCU4xwFgIbDAAKCRCw3p3W KL8TL0P4B/9YWver5uD/y/m0KScK2f3Z3mXJhME23vGBbMNlfwbr+meDMrJZ950CuWWnQ+d+ Ahe0w1X7e3wuLVODzjcReQ/v7b4JD3wwHxe+88tgB9byc0NXzlPJWBaWV01yB2/uefVKryAf AHYEd0gCRhx7eESgNBe3+YqWAQawunMlycsqKa09dBDL1PFRosF708ic9346GLHRc6Vj5SRA UTHnQqLetIOXZm3a2eQ1gpQK9MmruO86Vo93p39bS1mqnLLspVrL4rhoyhsOyh0Hd28QCzpJ wKeHTd0MAWAirmewHXWPco8p1Wg+V+5xfZzuQY0f4tQxvOpXpt4gQ1817GQ5/Ed/wsDtBBgB CAAgFiEEhRJncuj2BJSl0Jf3sN6d1ii/Ey8FAlrd8NACGwIAgQkQsN6d1ii/Ey92IAQZFggA HRYhBFMtsHpB9jjzHji4HoBcYbtP2GO+BQJa3fDQAAoJEIBcYbtP2GO+TYsA/30H/0V6cr/W V+J/FCayg6uNtm3MJLo4rE+o4sdpjjsGAQCooqffpgA+luTT13YZNV62hAnCLKXH9n3+ZAgJ RtAyDWk1B/0SMDVs1wxufMkKC3Q/1D3BYIvBlrTVKdBYXPxngcRoqV2J77lscEvkLNUGsu/z W2pf7+P3mWWlrPMJdlbax00vevyBeqtqNKjHstHatgMZ2W0CFC4hJ3YEetuRBURYPiGzuJXU pAd7a7BdsqWC4o+GTm5tnGrCyD+4gfDSpkOT53S/GNO07YkPkm/8J4OBoFfgSaCnQ1izwgJQ jIpcG2fPCI2/hxf2oqXPYbKr1v4Z1wthmoyUgGN0LPTIm+B5vdY82wI5qe9uN6UOGyTH2B3p hRQUWqCwu2sqkI3LLbTdrnyDZaixT2T0f4tyF5Lfs+Ha8xVMhIyzNb1byDI5FKCb
  • Cc: "Xen-devel <xen-devel@xxxxxxxxxxxxx>" <xen-devel@xxxxxxxxxxxxx>, Wei Liu <wei.liu2@xxxxxxxxxx>, Roger Pau Monne <roger.pau@xxxxxxxxxx>
  • Delivery-date: Mon, 04 Feb 2019 16:10:09 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
  • Openpgp: preference=signencrypt

On 04/02/2019 17:06, Jan Beulich wrote:
>>>> On 04.02.19 at 15:58, <andrew.cooper3@xxxxxxxxxx> wrote:
>> On 04/02/2019 14:44, Jan Beulich wrote:
>>>>>> On 04.02.19 at 15:22, <andrew.cooper3@xxxxxxxxxx> wrote:
>>>> On 04/02/2019 13:53, Jan Beulich wrote:
>>>>>>>> On 04.02.19 at 12:41, <andrew.cooper3@xxxxxxxxxx> wrote:
>>>>>> @@ -64,37 +54,37 @@ static DEFINE_PER_CPU(struct vcpu *, last_vcpu);
>>>>>>  static int __init parse_vpmu_params(const char *s)
>>>>>>  {
>>>>>>      const char *ss;
>>>>>> +    int rc = 0, val;
>>>>>> +
>>>>>> +    do {
>>>>>> +        ss = strchr(s, ',');
>>>>>> +        if ( !ss )
>>>>>> +            ss = strchr(s, '\0');
>>>>>> +
>>>>>> +        if ( (val = parse_bool(s, ss)) >= 0 )
>>>>>> +            opt_vpmu_enabled = val;
>>>>>> +        else if ( !cmdline_strcmp(s, "bts") )
>>>>>> +            vpmu_features |= XENPMU_FEATURE_INTEL_BTS;
>>>>>> +        else if ( !cmdline_strcmp(s, "ipc") )
>>>>>> +            vpmu_features |= XENPMU_FEATURE_IPC_ONLY;
>>>>>> +        else if ( !cmdline_strcmp(s, "arch") )
>>>>>> +            vpmu_features |= XENPMU_FEATURE_ARCH_ONLY;
>>>>>> +        else
>>>>>> +            rc = -EINVAL;
>>>>>>  
>>>>>> -    switch ( parse_bool(s, NULL) )
>>>>>> -    {
>>>>>> -    case 0:
>>>>>> -        break;
>>>>>> -    default:
>>>>>> -        do {
>>>>>> -            ss = strchr(s, ',');
>>>>>> -            if ( !ss )
>>>>>> -                ss = strchr(s, '\0');
>>>>>> -
>>>>>> -            if ( !cmdline_strcmp(s, "bts") )
>>>>>> -                vpmu_features |= XENPMU_FEATURE_INTEL_BTS;
>>>>>> -            else if ( !cmdline_strcmp(s, "ipc") )
>>>>>> -                vpmu_features |= XENPMU_FEATURE_IPC_ONLY;
>>>>>> -            else if ( !cmdline_strcmp(s, "arch") )
>>>>>> -                vpmu_features |= XENPMU_FEATURE_ARCH_ONLY;
>>>>>> -            else
>>>>>> -                return -EINVAL;
>>>>>> +        s = ss + 1;
>>>>>> +    } while ( *ss );
>>>>>> +
>>>>>> +    /* Selecting bts/ipc/arch forces vpmu to enabled. */
>>>>>> +    if ( vpmu_features )
>>>>>> +        opt_vpmu_enabled = true;
>>>>> If you want to retain original behavior, the condition here would need
>>>>> to be "!rc && vpmu_features". It's not clear whether your modification
>>>>> in this regard is intentional.
>>>> Oh - that wasn't intentional.
>>>>
>>>> An alternative, now I think about it, is to just have the <bool>=false
>>>> case clear vpmu_features.  This is new behaviour, but it is more
>>>> consistent with how other options work, and it wasn't expressable before.
>>> Generally - yes. But what would e.g. "vpmu=off,ipc" end up doing in
>>> your new model?
>>
>> The use of vpmu_features is somewhat weird.  "bts" acts as an extra
>> feature on top of "generally on", whereas "ipc" and "arch" act as
>> restrictions on top of "generally on".
> 
> Okay let's go that route then.

Release-acked-by: Juergen Gross <jgross@xxxxxxxx>


Juergen

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