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b=qP1ZdpyNWmLvk551LewC9g5FcbS40Ded0BtXmVIEgB3p FSKVfTGvKRF9fzGLSaUwYy0wQSV8U549vl/CTemu2Hoy7vWVlnGXLiDU0+u4gxmB nNKQFdOKr5HxQmSsT/hNwq1Vf5Kdk8/TtCfXzUeS6sXyjd2WkswN7pvsyzxfvxGi ndgOwnRJhjN8BBJ7/GCkap94hBvgl64u7VhMgv1mwzBAt5RWb8ykgfkHEmcjsQI6 heRHxyCki2hYSMTYzk99do+gE/NivsoXL6iQ7nT5RZHB2Q2Kq9p+F2GxAgfENbnT 4Agg9x85875VonXaDLL91DFPWAm0BpFT3uxGOhrZKw== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvhedrudeigddutdelucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhepfffhvfevuffkfhggtggujgesghdtreertddtjeenucfhrhhomhepofgrrhgv khcuofgrrhgtiiihkhhofihskhhiqdfikphrvggtkhhiuceomhgrrhhmrghrvghksehinh hvihhsihgslhgvthhhihhnghhslhgrsgdrtghomheqnecuggftrfgrthhtvghrnhepgfdu leetfeevhfefheeiteeliefhjefhleduveetteekveettddvgeeuteefjedunecuvehluh hsthgvrhfuihiivgeptdenucfrrghrrghmpehmrghilhhfrhhomhepmhgrrhhmrghrvghk sehinhhvihhsihgslhgvthhhihhnghhslhgrsgdrtghomh X-ME-Proxy: Feedback-ID: i1568416f:Fastmail Date: Tue, 6 Dec 2022 19:12:06 +0100 From: Marek =?utf-8?Q?Marczykowski-G=C3=B3recki?= To: Demi Marie Obenour Cc: Andrew Cooper , "xen-devel@lists.xenproject.org" , Jan Beulich , Roger Pau Monne , Wei Liu , George Dunlap , "Tim (Xen.org)" , Juergen Gross Subject: Re: [RFC PATCH 8/8] Use Linux's PAT Message-ID: References: <9f0bd911ba6c7fe1b7285f232154d42807145ced.1670300446.git.demi@invisiblethingslab.com> <4b2a87e1-89d1-b5fb-bd92-b891c8cea98a@citrix.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="rYRF28xWz3K770gH" Content-Disposition: inline In-Reply-To: --rYRF28xWz3K770gH Content-Type: text/plain; protected-headers=v1; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Date: Tue, 6 Dec 2022 19:12:06 +0100 From: Marek =?utf-8?Q?Marczykowski-G=C3=B3recki?= To: Demi Marie Obenour Cc: Andrew Cooper , "xen-devel@lists.xenproject.org" , Jan Beulich , Roger Pau Monne , Wei Liu , George Dunlap , "Tim (Xen.org)" , Juergen Gross Subject: Re: [RFC PATCH 8/8] Use Linux's PAT On Tue, Dec 06, 2022 at 01:01:41PM -0500, Demi Marie Obenour wrote: > On Tue, Dec 06, 2022 at 11:38:03AM +0000, Andrew Cooper wrote: > > On 06/12/2022 04:33, Demi Marie Obenour wrote: > > > This is purely for testing, to see if it works around a bug in i915. = It > > > is not intended to be merged. > > > > > > NOT-signed-off-by: DO NOT MERGE > >=20 > > Following up on Marek's report on IRC/Matrix, you're saying that this > > change does actually fix screen corruption issues on AlderLake, and > > something on TigerLake too? >=20 > Correct >=20 > > If that is actually the case, then one of two things is happening.=C2= =A0 Either, > >=20 > > 1) Drivers in Linux are bypassing the regular caching APIs, or >=20 > This would not surprise me at all. >=20 > > 2) The translation logic between Linux's idea of cacheability and Xen's > > PAT values is buggy. >=20 > How could I check for this? See Andy's unit test idea on #xendevel: as a pretty simple "unit" test in dom0, it might be a good idea to have a module which watches the PTE in question, and cycles through various of the memremap_*() APIs and checks the raw PTE that gets written after Linux and Xen are done fighting with it --=20 Best Regards, Marek Marczykowski-G=C3=B3recki Invisible Things Lab --rYRF28xWz3K770gH Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEhrpukzGPukRmQqkK24/THMrX1ywFAmOPhfcACgkQ24/THMrX 1ywR9gf/VnJy5XbHiFGOloFmTa5fTOhJ6O/hLcfubRva3WtUKtovyZmFRV0aAKkJ TUvFnFhLoidxDOjQ+eqCJvWjJSCOuZ7VRAvj1TJq3uWNA6d2xZSZcDB0Ptj69vr7 7vpHkOojQlGkEnqKnBqsWYaRX6+xe7YVkzkOaUJdZYnDd5JSiHdKW0rXOIMWuQW0 BtlfiMJ8wpywhoC1Uk3w87Fg/HvHa3xaxDLr0j3lW7YGqfRo0i+IFYd9dwvHCOtb dnZEZBbR4ELdQ8WzrICuzjdpQlBeOu/ffNHEEsKRGg+fofFGJlNXdgUrnY51/Djx YiF8BJajnyRmvlArvCJD1qUgImAXnw== =FiSR -----END PGP SIGNATURE----- --rYRF28xWz3K770gH--