From mboxrd@z Thu Jan 1 00:00:00 1970 From: Zhenyu Wang Subject: Re: [PATCH 1/1] Revert "iommu/vt-d: Clean up pasid quirk for pre-production devices" Date: Mon, 16 Jul 2018 15:53:09 +0800 Message-ID: <20180716075309.GN1267@zhen-hp.sh.intel.com> References: <1531031001-5783-1-git-send-email-baolu.lu@linux.intel.com> <5B4C34E4.30004@linux.intel.com> Reply-To: Zhenyu Wang Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============7704700869497265899==" Return-path: In-Reply-To: <5B4C34E4.30004-VuQAYsv1563Yd54FQh9/CA@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Lu Baolu Cc: ashok.raj-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, David Woodhouse , intel-gfx-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org List-Id: iommu@lists.linux-foundation.org --===============7704700869497265899== Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="kd7cwL6IYJrQFfWn" Content-Disposition: inline --kd7cwL6IYJrQFfWn Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 2018.07.16 14:02:12 +0800, Lu Baolu wrote: > Hi Joerg, >=20 > The graphic guys are looking forward to having this in 4.18. > Is it possible to take it in the following rcs? >=20 This breakes intel gfx driver in 4.18 when gfx dmar is on. Please include this fix ASAP. Tested-by: Zhenyu Wang thanks! >=20 > On 07/08/2018 02:23 PM, Lu Baolu wrote: > > This reverts commit ab96746aaa344fb720a198245a837e266fad3b62. > > > > The commit ab96746aaa34 ("iommu/vt-d: Clean up pasid quirk for > > pre-production devices") triggers ECS mode on some platforms > > which have broken ECS support. As the result, graphic device > > will be inoperable on boot. > > > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=3D107017 > > > > Cc: Ashok Raj > > Signed-off-by: Lu Baolu > > --- > > drivers/iommu/intel-iommu.c | 32 ++++++++++++++++++++++++++++++-- > > include/linux/intel-iommu.h | 1 + > > 2 files changed, 31 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c > > index b344a88..115ff26 100644 > > --- a/drivers/iommu/intel-iommu.c > > +++ b/drivers/iommu/intel-iommu.c > > @@ -484,14 +484,37 @@ static int dmar_forcedac; > > static int intel_iommu_strict; > > static int intel_iommu_superpage =3D 1; > > static int intel_iommu_ecs =3D 1; > > +static int intel_iommu_pasid28; > > static int iommu_identity_mapping; > > =20 > > #define IDENTMAP_ALL 1 > > #define IDENTMAP_GFX 2 > > #define IDENTMAP_AZALIA 4 > > =20 > > -#define ecs_enabled(iommu) (intel_iommu_ecs && ecap_ecs(iommu->ecap)) > > -#define pasid_enabled(iommu) (ecs_enabled(iommu) && ecap_pasid(iommu->= ecap)) > > +/* Broadwell and Skylake have broken ECS support =E2=80=94 normal so-c= alled "second > > + * level" translation of DMA requests-without-PASID doesn't actually h= appen > > + * unless you also set the NESTE bit in an extended context-entry. Whi= ch of > > + * course means that SVM doesn't work because it's trying to do nested > > + * translation of the physical addresses it finds in the process page = tables, > > + * through the IOVA->phys mapping found in the "second level" page tab= les. > > + * > > + * The VT-d specification was retroactively changed to change the defi= nition > > + * of the capability bits and pretend that Broadwell/Skylake never hap= pened... > > + * but unfortunately the wrong bit was changed. It's ECS which is brok= en, but > > + * for some reason it was the PASID capability bit which was redefined= (from > > + * bit 28 on BDW/SKL to bit 40 in future). > > + * > > + * So our test for ECS needs to eschew those implementations which set= the old > > + * PASID capabiity bit 28, since those are the ones on which ECS is br= oken. > > + * Unless we are working around the 'pasid28' limitations, that is, by= putting > > + * the device into passthrough mode for normal DMA and thus masking th= e bug. > > + */ > > +#define ecs_enabled(iommu) (intel_iommu_ecs && ecap_ecs(iommu->ecap) &= & \ > > + (intel_iommu_pasid28 || !ecap_broken_pasid(iommu->ecap))) > > +/* PASID support is thus enabled if ECS is enabled and *either* of the= old > > + * or new capability bits are set. */ > > +#define pasid_enabled(iommu) (ecs_enabled(iommu) && \ > > + (ecap_pasid(iommu->ecap) || ecap_broken_pasid(iommu->ecap))) > > =20 > > int intel_iommu_gfx_mapped; > > EXPORT_SYMBOL_GPL(intel_iommu_gfx_mapped); > > @@ -554,6 +577,11 @@ static int __init intel_iommu_setup(char *str) > > printk(KERN_INFO > > "Intel-IOMMU: disable extended context table support\n"); > > intel_iommu_ecs =3D 0; > > + } else if (!strncmp(str, "pasid28", 7)) { > > + printk(KERN_INFO > > + "Intel-IOMMU: enable pre-production PASID support\n"); > > + intel_iommu_pasid28 =3D 1; > > + iommu_identity_mapping |=3D IDENTMAP_GFX; > > } else if (!strncmp(str, "tboot_noforce", 13)) { > > printk(KERN_INFO > > "Intel-IOMMU: not forcing on after tboot. This could expose securi= ty risk for tboot\n"); > > diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h > > index 1df9401..ef169d6 100644 > > --- a/include/linux/intel-iommu.h > > +++ b/include/linux/intel-iommu.h > > @@ -121,6 +121,7 @@ > > #define ecap_srs(e) ((e >> 31) & 0x1) > > #define ecap_ers(e) ((e >> 30) & 0x1) > > #define ecap_prs(e) ((e >> 29) & 0x1) > > +#define ecap_broken_pasid(e) ((e >> 28) & 0x1) > > #define ecap_dis(e) ((e >> 27) & 0x1) > > #define ecap_nest(e) ((e >> 26) & 0x1) > > #define ecap_mts(e) ((e >> 25) & 0x1) >=20 --=20 Open Source Technology Center, Intel ltd. $gpg --keyserver wwwkeys.pgp.net --recv-keys 4D781827 --kd7cwL6IYJrQFfWn Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iF0EARECAB0WIQTXuabgHDW6LPt9CICxBBozTXgYJwUCW0xO5QAKCRCxBBozTXgY JxcqAJ4q4apZs8P0KaW9SpeNJw7O+zpxQQCfXxLa3d/Ii8e/v/W8dEcKrZMlpxM= =r6f5 -----END PGP SIGNATURE----- --kd7cwL6IYJrQFfWn-- --===============7704700869497265899== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline --===============7704700869497265899==--