From mboxrd@z Thu Jan 1 00:00:00 1970 From: Olaf Hering Subject: Re: [PATCH 0/2] MMIO emulation fixes Date: Wed, 29 Aug 2018 12:36:18 +0200 Message-ID: <20180829103614.GA31376@aepfle.de> References: <5B6D86F302000078001DCF85@prv1-mh.provo.novell.com> <5B6DAF9F02000078001DD040@prv1-mh.provo.novell.com> <5B6DB69D02000078001DD06A@prv1-mh.provo.novell.com> <92ca69e5-98b1-61e4-817a-3868f829471a@citrix.com> <5B712A3502000078001DD514@prv1-mh.provo.novell.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============2958389639057470432==" Return-path: Received: from us1-rack-dfw2.inumbo.com ([104.130.134.6]) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1fuxps-0007gn-JB for xen-devel@lists.xenproject.org; Wed, 29 Aug 2018 10:36:29 +0000 In-Reply-To: <5B712A3502000078001DD514@prv1-mh.provo.novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" To: Jan Beulich Cc: George Dunlap , Andrew Cooper , Paul Durrant , george.dunlap@citrix.com, xen-devel List-Id: xen-devel@lists.xenproject.org --===============2958389639057470432== Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="WIyZ46R2i8wDzkSu" Content-Disposition: inline --WIyZ46R2i8wDzkSu Content-Type: text/plain; charset=utf-8 Content-Disposition: inline On Mon, Aug 13, Jan Beulich wrote: > And hence the consideration of mapping in an all zeros page > instead. This is because of the way __hvmemul_read() / > __hvm_copy() work: The latter doesn't tell its caller how many > bytes it was able to read, and hence the former considers the > entire range MMIO (and forwards the request for emulation). > Of course all of this is an issue only because > hvmemul_virtual_to_linear() sees no need to split the request > at the page boundary, due to the balloon driver having left in > place the mapping of the ballooned out page. Should perhaps __hvm_copy detect the fault and copy 0xf for the unavailable page into 'buf', and finally return success? Clearly something must be done at the Xen level. Olaf --WIyZ46R2i8wDzkSu Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iF0EARECAB0WIQSkRyP6Rn//f03pRUBdQqD6ppg2fgUCW4Z3HgAKCRBdQqD6ppg2 fhfZAKDk8uHYoaNDLDyLqrD5BwIB9r2YwgCfTvEUjUqnjcV+OniGNk1WURFrkrs= =Nac+ -----END PGP SIGNATURE----- --WIyZ46R2i8wDzkSu-- --===============2958389639057470432== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Content-Disposition: inline X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KWGVuLWRldmVs IG1haWxpbmcgbGlzdApYZW4tZGV2ZWxAbGlzdHMueGVucHJvamVjdC5vcmcKaHR0cHM6Ly9saXN0 cy54ZW5wcm9qZWN0Lm9yZy9tYWlsbWFuL2xpc3RpbmZvL3hlbi1kZXZlbA== --===============2958389639057470432==--