From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexey Kardashevskiy Date: Tue, 19 Jul 2022 03:18:32 +0000 Subject: Re: [PATCH kernel 3/3] powerpc/iommu: Add iommu_ops to report capabilities and allow blocking domain Message-Id: <00c41fa4-4e64-0a90-b06e-accdc662fa4d@ozlabs.ru> List-Id: References: <20220714081822.3717693-1-aik@ozlabs.ru> <20220714081822.3717693-4-aik@ozlabs.ru> <20220718180924.GE4609@nvidia.com> In-Reply-To: <20220718180924.GE4609@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Jason Gunthorpe Cc: linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org, kvm-ppc@vger.kernel.org, Deming Wang , Robin Murphy , Alex Williamson , Daniel Henrique Barboza , Fabiano Rosas , Murilo Opsfelder Araujo , Nicholas Piggin , Michael Ellerman On 19/07/2022 04:09, Jason Gunthorpe wrote: > On Thu, Jul 14, 2022 at 06:18:22PM +1000, Alexey Kardashevskiy wrote: > >> +/* >> + * A simple iommu_ops to allow less cruft in generic VFIO code. >> + */ >> +static bool spapr_tce_iommu_capable(enum iommu_cap cap) >> +{ >> + switch (cap) { >> + case IOMMU_CAP_CACHE_COHERENCY: > > I would add a remark here that it is because vfio is going to use > SPAPR mode but still checks that the iommu driver support coherency - > with out that detail it looks very strange to have caps without > implementing unmanaged domains > >> +static struct iommu_domain *spapr_tce_iommu_domain_alloc(unsigned int type) >> +{ >> + struct iommu_domain *dom; >> + >> + if (type != IOMMU_DOMAIN_BLOCKED) >> + return NULL; >> + >> + dom = kzalloc(sizeof(*dom), GFP_KERNEL); >> + if (!dom) >> + return NULL; >> + >> + dom->geometry.aperture_start = 0; >> + dom->geometry.aperture_end = ~0ULL; >> + dom->geometry.force_aperture = true; > > A blocked domain doesn't really have an aperture, all DMA is rejected, > so I think these can just be deleted and left at zero. > > Generally I'm suggesting drivers just use a static singleton instance > for the blocked domain instead of the allocation like this, but that > is a very minor nit. > >> +static struct iommu_device *spapr_tce_iommu_probe_device(struct device *dev) >> +{ >> + struct pci_dev *pdev; >> + struct pci_controller *hose; >> + >> + /* Weirdly iommu_device_register() assigns the same ops to all buses */ >> + if (!dev_is_pci(dev)) >> + return ERR_PTR(-EPERM); > > Less "weirdly", more by design. The iommu driver should check if the > given struct device is supported or not, it isn't really a bus > specific operation. > >> +static struct iommu_group *spapr_tce_iommu_device_group(struct device *dev) >> +{ >> + struct pci_controller *hose; >> + struct pci_dev *pdev; >> + >> + /* Weirdly iommu_device_register() assigns the same ops to all buses */ >> + if (!dev_is_pci(dev)) >> + return ERR_PTR(-EPERM); > > This doesn't need repeating, if probe_device() fails then this will > never be called. > >> +static int spapr_tce_iommu_attach_dev(struct iommu_domain *dom, >> + struct device *dev) >> +{ >> + struct iommu_group *grp = iommu_group_get(dev); >> + struct iommu_table_group *table_group; >> + int ret = -EINVAL; >> + >> + if (!grp) >> + return -ENODEV; >> + >> + table_group = iommu_group_get_iommudata(grp); >> + >> + if (dom->type = IOMMU_DOMAIN_BLOCKED) >> + ret = table_group->ops->take_ownership(table_group); > > Ideally there shouldn't be dom->type checks like this. > > > The blocking domain should have its own iommu_domain_ops that only > process the blocking operation. Ie call this like > spapr_tce_iommu_blocking_attach_dev() > > Instead of having a "default_domain_ops" leave it NULL and create a > spapr_tce_blocking_domain_ops with these two functions and assign it > to domain->ops when creating. Then it is really clear these functions > are only called for the DOMAIN_BLOCKED type and you don't need to > check it. > >> +static void spapr_tce_iommu_detach_dev(struct iommu_domain *dom, >> + struct device *dev) >> +{ >> + struct iommu_group *grp = iommu_group_get(dev); >> + struct iommu_table_group *table_group; >> + >> + table_group = iommu_group_get_iommudata(grp); >> + WARN_ON(dom->type != IOMMU_DOMAIN_BLOCKED); >> + table_group->ops->release_ownership(table_group); >> +} > > Ditto > >> +struct iommu_group *pSeries_pci_device_group(struct pci_controller *hose, >> + struct pci_dev *pdev) >> +{ >> + struct device_node *pdn, *dn = pdev->dev.of_node; >> + struct iommu_group *grp; >> + struct pci_dn *pci; >> + >> + pdn = pci_dma_find(dn, NULL); >> + if (!pdn || !PCI_DN(pdn)) >> + return ERR_PTR(-ENODEV); >> + >> + pci = PCI_DN(pdn); >> + if (!pci->table_group) >> + return ERR_PTR(-ENODEV); >> + >> + grp = pci->table_group->group; >> + if (!grp) >> + return ERR_PTR(-ENODEV); >> + >> + return iommu_group_ref_get(grp); > > Not for this series, but this is kind of backwards, the driver > specific data (ie the table_group) should be in > iommu_group_get_iommudata()... It is there but here we are getting from a device to a group - a device is not added to a group yet when iommu_probe_device() works and tries adding a device via iommu_group_get_for_dev(). >> diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c >> index 8a65ea61744c..3b53b466e49b 100644 >> --- a/drivers/vfio/vfio_iommu_spapr_tce.c >> +++ b/drivers/vfio/vfio_iommu_spapr_tce.c >> @@ -1152,8 +1152,6 @@ static void tce_iommu_release_ownership(struct tce_container *container, >> for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) >> if (container->tables[i]) >> table_group->ops->unset_window(table_group, i); >> - >> - table_group->ops->release_ownership(table_group); >> } >> >> static long tce_iommu_take_ownership(struct tce_container *container, >> @@ -1161,10 +1159,6 @@ static long tce_iommu_take_ownership(struct tce_container *container, >> { >> long i, ret = 0; >> >> - ret = table_group->ops->take_ownership(table_group); >> - if (ret) >> - return ret; >> - >> /* Set all windows to the new group */ >> for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) { >> struct iommu_table *tbl = container->tables[i]; >> @@ -1183,8 +1177,6 @@ static long tce_iommu_take_ownership(struct tce_container *container, >> for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) >> table_group->ops->unset_window(table_group, i); >> >> - table_group->ops->release_ownership(table_group); >> - > > This is great, makes alot of sense. > > Anyhow, it all looks fine to me as is even: > > Reviewed-by: Jason Gunthorpe Thanks. I'll try now to find an interested party to test this :) > > Jason -- Alexey