From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36620) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aQcX5-0008Qk-M3 for qemu-devel@nongnu.org; Tue, 02 Feb 2016 10:06:20 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aQcX0-00081h-2z for qemu-devel@nongnu.org; Tue, 02 Feb 2016 10:06:19 -0500 Received: from bombadil.infradead.org ([2001:1868:205::9]:47545) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aQcWz-00081P-PP for qemu-devel@nongnu.org; Tue, 02 Feb 2016 10:06:13 -0500 Message-ID: <1454425564.4788.61.camel@infradead.org> From: David Woodhouse Date: Tue, 02 Feb 2016 15:06:04 +0000 In-Reply-To: <1454424840.10542.18.camel@redhat.com> References: <1451994098-6972-1-git-send-email-kraxel@redhat.com> <1454009759.7183.7.camel@redhat.com> <1454051359.28516.28.camel@redhat.com> <1454090373.23148.11.camel@redhat.com> <003AAFE53969E14CB1F09B6FD68C3CD47BB681B7@ORSMSX106.amr.corp.intel.com> <1454262132.10542.1.camel@redhat.com> <003AAFE53969E14CB1F09B6FD68C3CD47BB6B475@ORSMSX106.amr.corp.intel.com> <1454413825.4788.49.camel@infradead.org> <1454424840.10542.18.camel@redhat.com> Content-Type: multipart/signed; micalg="sha-1"; protocol="application/x-pkcs7-signature"; boundary="=-u6om5P1M07AiNMDhWKPs" Mime-Version: 1.0 Subject: Re: [Qemu-devel] [Xen-devel] [iGVT-g] [vfio-users] [PATCH v3 00/11] igd passthrough chipset tweaks List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alex Williamson , "Tian, Kevin" , "Kay, Allen M" , Gerd Hoffmann Cc: "igvt-g@ml01.01.org" , "xen-devel@lists.xensource.com" , Eduardo Habkost , Stefano Stabellini , "qemu-devel@nongnu.org" , Cao jin , "vfio-users@redhat.com" --=-u6om5P1M07AiNMDhWKPs Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Tue, 2016-02-02 at 07:54 -0700, Alex Williamson wrote: >=20 > I first glance I like it, but there's a problem, it assumes there is a > host driver for the device that will permanently release the device from > the RMRR even after the device is unbound.=C2=A0=C2=A0Currently we don't = have a > requirement that the user must first bind the device to a native host > driver, unbind it, and only then is it eligible for device assignment. It doesn't *have* to be a full native driver. It can be a PCI quirk (the USB controllers could potentially do it that way, although they don't). Or a stub 'shut it down' driver, potentially even done somehow through VFIO. But fundamentally, in all of these cases you have to do *something* to stop the BIOS-controlled DMA. Otherwise the RMRR shouldn't have been there in the first place, surely? But for the gfx case... what *do* we have to do? Does the VMM (and the VM's BIOS, between them) have to provision a "stolen" region of guest memory and point the gfx framebuffer at that? Once we have a proper handle on precisely what needs to happen, we can have a better conversation about where/how to do that... --=20 David Woodhouse Open Source Technology Centre David.Woodhouse@intel.com Intel Corporation --=-u6om5P1M07AiNMDhWKPs Content-Type: application/x-pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExCzAJBgUrDgMCGgUAMIAGCSqGSIb3DQEHAQAAoIISjjCCBicw ggUPoAMCAQICAw3vNzANBgkqhkiG9w0BAQUFADCBjDELMAkGA1UEBhMCSUwxFjAUBgNVBAoTDVN0 YXJ0Q29tIEx0ZC4xKzApBgNVBAsTIlNlY3VyZSBEaWdpdGFsIENlcnRpZmljYXRlIFNpZ25pbmcx ODA2BgNVBAMTL1N0YXJ0Q29tIENsYXNzIDEgUHJpbWFyeSBJbnRlcm1lZGlhdGUgQ2xpZW50IENB MB4XDTE1MDUwNTA5NDM0MVoXDTE2MDUwNTA5NTMzNlowQjEcMBoGA1UEAwwTZHdtdzJAaW5mcmFk ZWFkLm9yZzEiMCAGCSqGSIb3DQEJARYTZHdtdzJAaW5mcmFkZWFkLm9yZzCCASIwDQYJKoZIhvcN AQEBBQADggEPADCCAQoCggEBAMkbm9kPbx1j/X4RVyf/pPKSYwelcco69TvnQQbKM8m8xkWjXJI1 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