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Re: [Xen-devel] [PATCH] xen: issue warning message when out of grant maptrack entries


  • To: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>, linux-kernel@xxxxxxxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxxx
  • From: Juergen Gross <jgross@xxxxxxxx>
  • Date: Tue, 18 Sep 2018 19:17:35 +0200
  • 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
  • Delivery-date: Tue, 18 Sep 2018 17:17:49 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
  • Openpgp: preference=signencrypt

On 18/09/18 19:03, Boris Ostrovsky wrote:
> On 9/18/18 5:32 AM, Juergen Gross wrote:
>> When a driver domain (e.g. dom0) is running out of maptrack entries it
>> can't map any more foreign domain pages. Instead of silently stalling
>> the affected domUs issue a rate limited warning in this case in order
>> to make it easier to detect that situation.
>>
>> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
>> ---
>>  drivers/xen/grant-table.c | 25 +++++++++++++++++++------
>>  1 file changed, 19 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
>> index 7bafa703a992..09f6ff8c1957 100644
>> --- a/drivers/xen/grant-table.c
>> +++ b/drivers/xen/grant-table.c
>> @@ -1040,18 +1040,31 @@ int gnttab_map_refs(struct gnttab_map_grant_ref 
>> *map_ops,
>>              return ret;
>>  
>>      for (i = 0; i < count; i++) {
>> -            /* Retry eagain maps */
>> -            if (map_ops[i].status == GNTST_eagain)
>> -                    gnttab_retry_eagain_gop(GNTTABOP_map_grant_ref, map_ops 
>> + i,
>> -                                            &map_ops[i].status, __func__);
>> -
>> -            if (map_ops[i].status == GNTST_okay) {
>> +            switch (map_ops[i].status) {
>> +            case GNTST_okay:
>> +            {
>>                      struct xen_page_foreign *foreign;
>>  
>>                      SetPageForeign(pages[i]);
>>                      foreign = xen_page_foreign(pages[i]);
>>                      foreign->domid = map_ops[i].dom;
>>                      foreign->gref = map_ops[i].ref;
>> +                    break;
>> +            }
>> +
>> +            case GNTST_no_device_space:
>> +                    pr_warn_ratelimited("maptrack limit reached, can't map 
>> all guest pages\n");
>> +                    break;
>> +
>> +            case GNTST_eagain:
>> +                    /* Retry eagain maps */
>> +                    gnttab_retry_eagain_gop(GNTTABOP_map_grant_ref,
>> +                                            map_ops + i,
>> +                                            &map_ops[i].status, __func__);
>> +                    break;
>> +
>> +            default:
>> +                    break;
>>              }
>>      }
> 
> 
> Should we pass 'i' instead of count to set_foreign_p2m_mapping() below?
> The loop there will skip entries that are in error, but does it make
> sense to do the hypercall for kmap_ops with count>i ?

The loop is running until the end, so i == count for the call of kmap_ops().


Juergen

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