[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [PATCH v2] x86emul: de-duplicate scatters to the same linear address


  • To: Jan Beulich <jbeulich@xxxxxxxx>
  • From: Roger Pau Monné <roger.pau@xxxxxxxxxx>
  • Date: Mon, 18 Oct 2021 13:19:55 +0200
  • Arc-authentication-results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=citrix.com; dmarc=pass action=none header.from=citrix.com; dkim=pass header.d=citrix.com; arc=none
  • Arc-message-signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=+PpxqIBmpSYx4p5gA0OY+PQaWpWDoOllj221jJ+5rHI=; b=kbuT1EgvDZd4LgmggbREUoi8gA9ZryNoeDqdgXPB5TC/QmV9R2zUQ4WFMeBnTZ+tXAw0WVHhumpjLpUpwNQWaakX9ujt87fiuF59gjruW+ACfBdzc8d+QaleXFyD1wCeE4wJMFOkclGKA/mfWlgwEMZnc5xr9MTvs3DsJJhq4GvOiEU89TT8ehbYTU2TNDglVqNX1tkfgP3S5XBYxkieGdoHmOCpo9IpwMtLmTlXnYb7fSy8nQ4GfB2Lg61p3sBSOvM6ioPrJ4ZDgY0LHtsscWXHlgO1KYPa9mB0N8r8+FRk0VUoP5zPVF2BSOr/BOiWlrySS2gdWhwq8u5Mq51PTw==
  • Arc-seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=Z0c4SlDj+sh74yafBKLG1EdN/OclO2KCewJEA7EBd6PeEZuLyrvlHiLFPTY8ZCqBMpZFXJJzYNkqT4Jta/gyo6SGtVzEf3NA9c2AkdHH6nqjFdUiNVq0uxkltQPmfyxof2LS6CJ/pNu9jJfhl1gHJHAKnszxZhmLrW3m0/4X0lOMjaPG87V2rPoWb3L1v8iUMg1WsGBQGYtemAGiTTLkk7wz6nHc/TL9klsu5MDdox+Z5q12CIlpPh6mMrplj2CMD+9w14y5D0lkAxx+QdWW0TNpTGEOe38ydawgRtxG/+3LcEpH/NXnIunU6LoJwmRm1RMgYTQ+HD+ub/K4JSITZw==
  • Authentication-results: esa5.hc3370-68.iphmx.com; dkim=pass (signature verified) header.i=@citrix.onmicrosoft.com
  • Cc: "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>
  • Delivery-date: Mon, 18 Oct 2021 11:20:41 +0000
  • Ironport-data: A9a23:sfEls6LE6v6C8HTyFE+RC5IlxSXFcZb7ZxGr2PjKsXjdYENS3zUPy 2IWDGqHPK2IM2ChKN0nbYiwoEoGvZfXz9dhHANlqX01Q3x08seUXt7xwmUcns+xwm8vaGo9s q3yv/GZdJhcokcxIn5BC5C5xZVG/fjgqoHUVaiUZ0ideSc+EH140Eo6y7Zg6mJVqYPR7z2l6 IuaT/L3YDdJ6xYsWo7Dw/vewP/HlK2aVAIw5jTSV9gS1LPtvyB94KYkDbOwNxPFrrx8RYZWc QphIIaRpQs19z91Yj+sfy2SnkciGtY+NiDW4pZatjTLbrGvaUXe345iXMfwZ3u7hB3Xx8Jv+ tdPv6e+WF5uDqqRgc8bSElxRnQW0a1uoNcrIFC6uM2XiUbHb2Ht07NlC0Re0Y8wo7gtRzsUr LpBdW5LPkvra+GemdpXTsF2gcsuNo/zNZ43sXB81zDJS/0hRPgvRo2XuY4Igmlr3KiiG97YS dokdwhEXi7DXCZrEVgYF6gAs8230yyXnzpw9wvO+PtfD3Lo5BN1+KjgNpzSYNPibdVYmAOUq 3zL+0z9AwoGL5qPxDyd6HWui+TT2yThV+o6Fre16/pri1273XEIBVsdUl7TnBWiohfgAZQFc RVSo3dw6/hpnKC2cjXjd0PgsmC2vBwWYNRBSqoK71yU4azPsy/MUwDoUQV9QNAhscY3Qxkj2 VmIg87lCFRTjVGFdZ6O3uzL9W3qaED5OUdHPHVeFVJUvLEPtalq1kqXJuuPBpJZmTEc9dvY+ DuNsDQlz4saicoGxs1XFniW3mry+PAlouMzjzg7v15JDCskPOZJhKTysDA3CMqsyq7DHzFtW 1Bfw6CjABgmV83lqcB0aLxl8EuVz/iEKibAplVkAoMs8T+gk1b6I9sMvGAjdR01bpxVEdMMX KM1kVkAjHO0FCDyBZKbnqrrU5h6pUQePYWNug/ogipmPcEqKV7vENBGbk+MxWH9+HXAYolkU ap3hf2EVC5AYYw+lWLeb75EjdcDm3BvrUuOFMuT50n2jtKjiIu9FO5t3K2mNbtisstpYWz9r r5iCid9404DCbKjPnSOrNd7wJJjBSFTOK0aYvd/L4arCgFnBHsgG7nWx7YgcJZihKNbiqHD+ XTVZ6OS4ACi7ZEeAQnVOH1ldp31WpNz8SAyMSA2ZA760Hk/e4e/qqwYcsJvL7Ug8eViy99yT uUEJJrcUqgeFGyf9mRPd4T5oaxjaA+v2VCEMR26bWVtZJVnXQHIpIPpJ1O96CkUAyOrnsIiu Ln8hBjDSJ8OSl06XsbbYf6i1X2run0ZlL4gVkfEOIALKk7t7JJrO2r6ifpue5MALhDKxz270 QeKAEhH+bmR8tFtqNSQ3PKKtYakFed6D3F2JWiD4ObkLzTe80qi3ZREDLSCcwfCWT6m466lf +hUka3xaaVVgFZQvoNgOL931qZitcD3rrpXwwk4TnXGa1OnVuFpLnWchJQds6RMwvlSuBesW 1LJ8d5fYO3bNMTgGV8XBQwkcuXciq1ExmiMtaw4cBfg+St63LubSkEDbRCDhRtUIKZxLI54k /wqv9Qb6lDnhxcnWjpcYvu4K4hYwqQ8bpga
  • Ironport-hdrordr: A9a23:ytVZpqDYlTBRnnDlHeg3sceALOsnbusQ8zAXPh9KJiC9I/b1qy nxppkmPH/P6Qr4WBkb6Le90Y27MAnhHP9OkPIs1NKZMjUO11HYTr2KgbGSpgEIXheOi9K1tp 0QDZSWaueAdGSS5PySiGLTc6dCsai6GeKT9J/jJh9WPH5XgspbnmFE42igYylLrF4sP+tEKH PQ3LsMmxOQPVAsKuirDHgMWObO4/XNiZLdeBYDQzoq8hOHgz+E4KPzV0Hw5GZTbxp/hZMZtU TVmQ3w4auu99m91x/nzmfWq7BbgsHoxNdvDNGFzuIVNjLvoAC1Y5kJYczOgBkF5MWUrHo6mt jFpBkte+x19nPqZ2mw5SDg3gHxuQxeokPK+Bu9uz/OsMb5TDU1B45qnoRCaCbU7EImoZVVzL 9L93jxjesXMTrw2ADGo/TYXRBjkUS55VA4l/QIsnBZWYwCLJdMsI0k+l9PGptoJlO11GkeKp gsMCjg3ocVTbvDBEqp+1WHgebcEUjbJy32AnTr4aeuonxrdHMQ9Tpv+CVQpAZGyHqRI6M0kt gsCZ4Y542mePVmGp6VNN1xMfdfNVa9My4kEFjiaWgPR5t3cE4klfbMkcEIDaeRCdo18Kc=
  • Ironport-sdr: J+9a7fkDSHlHMvDhPveA7cpB6qPxXznd9DfnDw0EX/WfFWoftYR/vStqBzQm9IAarzl6kHOpRA P87MVcugIBqmET6njZJ2L3WnN1/hAY9FXCIx7xXYhOB9B9Em754pJN4Ph46VNegSxcLq+FTih8 0geBo7et+P1ta706t9zb2UR/8TOmhnskPR1+FPBH1mdC/ETjUiGytZkgqi4N5fcHXKe87g2/xN sXMeOVJNYNDvV8yiGtTu/Qj0y0PL2R8nJzpyiWnUGQoyY2Vajmt9EnmQlvxyjlkvINBmBcF8wp lvIAr22or0PHBXvR1lg6y1Wk
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

On Thu, May 20, 2021 at 03:34:28PM +0200, Jan Beulich wrote:
> The SDM specifically allows for earlier writes to fully overlapping
> ranges to be dropped. If a guest did so, hvmemul_phys_mmio_access()
> would crash it if varying data was written to the same address. Detect
> overlaps early, as doing so in hvmemul_{linear,phys}_mmio_access() would
> be quite a bit more difficult. To maintain proper faulting behavior,
> instead of dropping earlier write instances of fully overlapping slots
> altogether, write the data of the final of these slots multiple times.

Is it possible for a later (non duplicated slot) to cause a fault
ending the instruction without reaching that final slot that contains
the written data?

Thanks, Roger.



 


Rackspace

Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.