From: Pierre Morel <pmorel@linux.ibm.com> To: Cornelia Huck <cohuck@redhat.com>, Halil Pasic <pasic@linux.ibm.com> Cc: linux-kernel@vger.kernel.org, borntraeger@de.ibm.com, frankja@linux.ibm.com, mst@redhat.com, jasowang@redhat.com, kvm@vger.kernel.org, linux-s390@vger.kernel.org, virtualization@lists.linux-foundation.org, thomas.lendacky@amd.com, david@gibson.dropbear.id.au, linuxram@us.ibm.com, heiko.carstens@de.ibm.com, gor@linux.ibm.com Subject: Re: [PATCH v3 1/1] s390: virtio: let arch accept devices without IOMMU feature Date: Mon, 29 Jun 2020 15:14:04 +0200 [thread overview] Message-ID: <7fe6e9ab-fd5a-3f92-1f3a-f9e6805d3730@linux.ibm.com> (raw) In-Reply-To: <20200619112051.74babdb1.cohuck@redhat.com> On 2020-06-19 11:20, Cornelia Huck wrote: > On Thu, 18 Jun 2020 00:29:56 +0200 > Halil Pasic <pasic@linux.ibm.com> wrote: > >> On Wed, 17 Jun 2020 12:43:57 +0200 >> Pierre Morel <pmorel@linux.ibm.com> wrote: ... >> >> But since this can be rewritten any time, let's go with the option >> people already agree with, instead of more discussion. > > Yes, there's nothing wrong with the patch as-is. > > Acked-by: Cornelia Huck <cohuck@redhat.com> Thanks, > > Which tree should this go through? Virtio? s390? > >> >> Just another question. Do we want this backported? Do we need cc stable? > > It does change behaviour of virtio-ccw devices; but then, it only > fences off configurations that would not have worked anyway. > Distributions should probably pick this; but I do not consider it > strictly a "fix" (more a mitigation for broken configurations), so I'm > not sure whether stable applies. > >> [..] >> >> >>> int virtio_finalize_features(struct virtio_device *dev) >>> { >>> int ret = dev->config->finalize_features(dev); >>> @@ -179,6 +194,13 @@ int virtio_finalize_features(struct virtio_device *dev) >>> if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) >>> return 0; >>> >>> + if (arch_needs_virtio_iommu_platform(dev) && >>> + !virtio_has_feature(dev, VIRTIO_F_IOMMU_PLATFORM)) { >>> + dev_warn(&dev->dev, >>> + "virtio: device must provide VIRTIO_F_IOMMU_PLATFORM\n"); >> >> I'm not sure, divulging the current Linux name of this feature bit is a >> good idea, but if everybody else is fine with this, I don't care that > > Not sure if that feature name will ever change, as it is exported in > headers. At most, we might want to add the new ACCESS_PLATFORM define > and keep the old one, but that would still mean some churn. > >> much. An alternative would be: >> "virtio: device falsely claims to have full access to the memory, >> aborting the device" > > "virtio: device does not work with limited memory access" ? > > But no issue with keeping the current message. > If it is OK, I would like to specify that the arch is responsible to accept or not the device. The reason why the device is not accepted without IOMMU_PLATFORM is arch specific. Regards, Pierre -- Pierre Morel IBM Lab Boeblingen
WARNING: multiple messages have this Message-ID (diff)
From: Pierre Morel <pmorel@linux.ibm.com> To: Cornelia Huck <cohuck@redhat.com>, Halil Pasic <pasic@linux.ibm.com> Cc: gor@linux.ibm.com, linux-s390@vger.kernel.org, frankja@linux.ibm.com, kvm@vger.kernel.org, mst@redhat.com, heiko.carstens@de.ibm.com, linuxram@us.ibm.com, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, borntraeger@de.ibm.com, thomas.lendacky@amd.com, david@gibson.dropbear.id.au Subject: Re: [PATCH v3 1/1] s390: virtio: let arch accept devices without IOMMU feature Date: Mon, 29 Jun 2020 15:14:04 +0200 [thread overview] Message-ID: <7fe6e9ab-fd5a-3f92-1f3a-f9e6805d3730@linux.ibm.com> (raw) In-Reply-To: <20200619112051.74babdb1.cohuck@redhat.com> On 2020-06-19 11:20, Cornelia Huck wrote: > On Thu, 18 Jun 2020 00:29:56 +0200 > Halil Pasic <pasic@linux.ibm.com> wrote: > >> On Wed, 17 Jun 2020 12:43:57 +0200 >> Pierre Morel <pmorel@linux.ibm.com> wrote: ... >> >> But since this can be rewritten any time, let's go with the option >> people already agree with, instead of more discussion. > > Yes, there's nothing wrong with the patch as-is. > > Acked-by: Cornelia Huck <cohuck@redhat.com> Thanks, > > Which tree should this go through? Virtio? s390? > >> >> Just another question. Do we want this backported? Do we need cc stable? > > It does change behaviour of virtio-ccw devices; but then, it only > fences off configurations that would not have worked anyway. > Distributions should probably pick this; but I do not consider it > strictly a "fix" (more a mitigation for broken configurations), so I'm > not sure whether stable applies. > >> [..] >> >> >>> int virtio_finalize_features(struct virtio_device *dev) >>> { >>> int ret = dev->config->finalize_features(dev); >>> @@ -179,6 +194,13 @@ int virtio_finalize_features(struct virtio_device *dev) >>> if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) >>> return 0; >>> >>> + if (arch_needs_virtio_iommu_platform(dev) && >>> + !virtio_has_feature(dev, VIRTIO_F_IOMMU_PLATFORM)) { >>> + dev_warn(&dev->dev, >>> + "virtio: device must provide VIRTIO_F_IOMMU_PLATFORM\n"); >> >> I'm not sure, divulging the current Linux name of this feature bit is a >> good idea, but if everybody else is fine with this, I don't care that > > Not sure if that feature name will ever change, as it is exported in > headers. At most, we might want to add the new ACCESS_PLATFORM define > and keep the old one, but that would still mean some churn. > >> much. An alternative would be: >> "virtio: device falsely claims to have full access to the memory, >> aborting the device" > > "virtio: device does not work with limited memory access" ? > > But no issue with keeping the current message. > If it is OK, I would like to specify that the arch is responsible to accept or not the device. The reason why the device is not accepted without IOMMU_PLATFORM is arch specific. Regards, Pierre -- Pierre Morel IBM Lab Boeblingen
next prev parent reply other threads:[~2020-06-29 18:49 UTC|newest] Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-06-17 10:43 [PATCH v3 0/1] s390: virtio: let arch choose to accept devices without IOMMU feature Pierre Morel 2020-06-17 10:43 ` [PATCH v3 1/1] s390: virtio: let arch " Pierre Morel 2020-06-17 11:22 ` Heiko Carstens 2020-06-17 11:59 ` Pierre Morel 2020-06-17 13:36 ` Tom Lendacky 2020-06-17 14:12 ` Pierre Morel 2020-06-17 22:29 ` Halil Pasic 2020-06-19 9:20 ` Cornelia Huck 2020-06-19 12:02 ` Halil Pasic 2020-06-19 12:02 ` Halil Pasic 2020-06-29 13:15 ` Pierre Morel 2020-06-29 13:15 ` Pierre Morel 2020-06-29 13:14 ` Pierre Morel [this message] 2020-06-29 13:14 ` Pierre Morel 2020-06-29 13:44 ` Cornelia Huck 2020-06-29 13:44 ` Cornelia Huck 2020-06-29 16:10 ` Pierre Morel 2020-06-29 16:10 ` Pierre Morel 2020-06-29 13:21 ` Pierre Morel 2020-06-29 13:21 ` Pierre Morel 2020-06-29 15:57 ` Michael S. Tsirkin 2020-06-29 15:57 ` Michael S. Tsirkin 2020-06-29 16:05 ` Cornelia Huck 2020-06-29 16:05 ` Cornelia Huck 2020-07-02 13:03 ` Pierre Morel 2020-07-06 13:37 ` Pierre Morel 2020-07-06 14:33 ` Cornelia Huck 2020-07-06 15:01 ` Pierre Morel 2020-06-29 16:09 ` Pierre Morel 2020-06-29 16:09 ` Pierre Morel 2020-06-29 16:09 ` Michael S. Tsirkin 2020-06-29 16:09 ` Michael S. Tsirkin 2020-06-29 16:48 ` Pierre Morel 2020-06-29 16:48 ` Pierre Morel 2020-06-29 21:18 ` Michael S. Tsirkin 2020-06-29 21:18 ` Michael S. Tsirkin 2020-06-30 7:08 ` Cornelia Huck
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