From mboxrd@z Thu Jan 1 00:00:00 1970 From: Will Deacon Subject: Re: [PATCH v2 5/5] iommu: Allow default domain type to be set on the kernel command line Date: Tue, 21 Mar 2017 18:17:29 +0000 Message-ID: <20170321181729.GG30948@arm.com> References: <1489178976-15353-1-git-send-email-will.deacon@arm.com> <1489178976-15353-6-git-send-email-will.deacon@arm.com> <20170321154527.GB29659@8bytes.org> <20170321172137.GF30948@arm.com> <807ecbb0-c9d7-fc0a-25d2-93b5c4374107@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <807ecbb0-c9d7-fc0a-25d2-93b5c4374107-5wv7dgnIgG8@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: Robin Murphy Cc: iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: iommu@lists.linux-foundation.org On Tue, Mar 21, 2017 at 05:46:29PM +0000, Robin Murphy wrote: > On 21/03/17 17:21, Will Deacon wrote: > > On Tue, Mar 21, 2017 at 04:45:27PM +0100, Joerg Roedel wrote: > >> On Fri, Mar 10, 2017 at 08:49:36PM +0000, Will Deacon wrote: > >>> @@ -1014,8 +1027,8 @@ struct iommu_group *iommu_group_get_for_dev(struct device *dev) > >>> * IOMMU driver. > >>> */ > >>> if (!group->default_domain) { > >>> - group->default_domain = __iommu_domain_alloc(dev->bus, > >>> - IOMMU_DOMAIN_DMA); > >>> + group->default_domain = > >>> + __iommu_domain_alloc(dev->bus, iommu_def_domain_type); > >> > >> It would be good to have a fall-back here if we are talking to an IOMMU > >> driver that uses default domains, but does not support identity-mapped > >> domains (yet). Exynos and Rockchip IOMMU drivers seem to fall into this > >> category. A dev_warn() also makes sense in case allocating a identity > >> domain fails. > > > > Sure, something like the diff below? > > > > Will > > > > --->8 > > > > > > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > > index 42a842e3f95f..f787626a745d 100644 > > --- a/drivers/iommu/iommu.c > > +++ b/drivers/iommu/iommu.c > > @@ -1027,10 +1027,19 @@ struct iommu_group *iommu_group_get_for_dev(struct device *dev) > > * IOMMU driver. > > */ > > if (!group->default_domain) { > > - group->default_domain = > > - __iommu_domain_alloc(dev->bus, iommu_def_domain_type); > > + struct iommu_domain *dom; > > + > > + dom = __iommu_domain_alloc(dev->bus, iommu_def_domain_type); > > + if (!dom) { > > + dev_warn(dev, > > + "failed to allocate default IOMMU domain of type %u; falling back to IOMMU_DOMAIN_DMA", > > + iommu_def_domain_type); > > Conversely, that's going to be noisy if iommu_def_domain_type was > IOMMU_DOMAIN_DMA to begin with. I think it makes sense to warn if the > user asked for a specific default domain type on the command line and > that didn't work, but maybe not to bother otherwise. Plus, if they asked > for passthrough, then not allocating a default domain at all is probably > closer to the desired result than installing a DMA ops domain would be. You're right -- I'll hack this about to check if the default type isn't DOMAIN_DMA before warning about the allocation failure. Cheers, Will From mboxrd@z Thu Jan 1 00:00:00 1970 From: will.deacon@arm.com (Will Deacon) Date: Tue, 21 Mar 2017 18:17:29 +0000 Subject: [PATCH v2 5/5] iommu: Allow default domain type to be set on the kernel command line In-Reply-To: <807ecbb0-c9d7-fc0a-25d2-93b5c4374107@arm.com> References: <1489178976-15353-1-git-send-email-will.deacon@arm.com> <1489178976-15353-6-git-send-email-will.deacon@arm.com> <20170321154527.GB29659@8bytes.org> <20170321172137.GF30948@arm.com> <807ecbb0-c9d7-fc0a-25d2-93b5c4374107@arm.com> Message-ID: <20170321181729.GG30948@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tue, Mar 21, 2017 at 05:46:29PM +0000, Robin Murphy wrote: > On 21/03/17 17:21, Will Deacon wrote: > > On Tue, Mar 21, 2017 at 04:45:27PM +0100, Joerg Roedel wrote: > >> On Fri, Mar 10, 2017 at 08:49:36PM +0000, Will Deacon wrote: > >>> @@ -1014,8 +1027,8 @@ struct iommu_group *iommu_group_get_for_dev(struct device *dev) > >>> * IOMMU driver. > >>> */ > >>> if (!group->default_domain) { > >>> - group->default_domain = __iommu_domain_alloc(dev->bus, > >>> - IOMMU_DOMAIN_DMA); > >>> + group->default_domain = > >>> + __iommu_domain_alloc(dev->bus, iommu_def_domain_type); > >> > >> It would be good to have a fall-back here if we are talking to an IOMMU > >> driver that uses default domains, but does not support identity-mapped > >> domains (yet). Exynos and Rockchip IOMMU drivers seem to fall into this > >> category. A dev_warn() also makes sense in case allocating a identity > >> domain fails. > > > > Sure, something like the diff below? > > > > Will > > > > --->8 > > > > > > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > > index 42a842e3f95f..f787626a745d 100644 > > --- a/drivers/iommu/iommu.c > > +++ b/drivers/iommu/iommu.c > > @@ -1027,10 +1027,19 @@ struct iommu_group *iommu_group_get_for_dev(struct device *dev) > > * IOMMU driver. > > */ > > if (!group->default_domain) { > > - group->default_domain = > > - __iommu_domain_alloc(dev->bus, iommu_def_domain_type); > > + struct iommu_domain *dom; > > + > > + dom = __iommu_domain_alloc(dev->bus, iommu_def_domain_type); > > + if (!dom) { > > + dev_warn(dev, > > + "failed to allocate default IOMMU domain of type %u; falling back to IOMMU_DOMAIN_DMA", > > + iommu_def_domain_type); > > Conversely, that's going to be noisy if iommu_def_domain_type was > IOMMU_DOMAIN_DMA to begin with. I think it makes sense to warn if the > user asked for a specific default domain type on the command line and > that didn't work, but maybe not to bother otherwise. Plus, if they asked > for passthrough, then not allocating a default domain at all is probably > closer to the desired result than installing a DMA ops domain would be. You're right -- I'll hack this about to check if the default type isn't DOMAIN_DMA before warning about the allocation failure. Cheers, Will