Hi Baolu, Appreciate the thorough review, comments inline.
On Sat, 26 Oct 2019 10:01:19 +0800 Lu Baolu <[email protected]> wrote: > Hi, > > On 10/25/19 3:55 AM, Jacob Pan wrote: > > When supporting guest SVA with emulated IOMMU, the guest PASID > > table is shadowed in VMM. Updates to guest vIOMMU PASID table > > will result in PASID cache flush which will be passed down to > > the host as bind guest PASID calls. > > > > For the SL page tables, it will be harvested from device's > > default domain (request w/o PASID), or aux domain in case of > > mediated device. > > > > .-------------. .---------------------------. > > | vIOMMU | | Guest process CR3, FL only| > > | | '---------------------------' > > .----------------/ > > | PASID Entry |--- PASID cache flush - > > '-------------' | > > | | V > > | | CR3 in GPA > > '-------------' > > Guest > > ------| Shadow |--------------------------|-------- > > v v v > > Host > > .-------------. .----------------------. > > | pIOMMU | | Bind FL for GVA-GPA | > > | | '----------------------' > > .----------------/ | > > | PASID Entry | V (Nested xlate) > > '----------------\.------------------------------. > > | | |SL for GPA-HPA, default domain| > > | | '------------------------------' > > '-------------' > > Where: > > - FL = First level/stage one page tables > > - SL = Second level/stage two page tables > > > > Signed-off-by: Jacob Pan <[email protected]> > > Signed-off-by: Liu, Yi L <[email protected]> > > --- > > drivers/iommu/intel-iommu.c | 4 + > > drivers/iommu/intel-svm.c | 184 > > ++++++++++++++++++++++++++++++++++++++++++++ > > include/linux/intel-iommu.h | 8 +- include/linux/intel-svm.h | > > 17 ++++ 4 files changed, 212 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/iommu/intel-iommu.c > > b/drivers/iommu/intel-iommu.c index acd1ac787d8b..5fab32fbc4b4 > > 100644 --- a/drivers/iommu/intel-iommu.c > > +++ b/drivers/iommu/intel-iommu.c > > @@ -6026,6 +6026,10 @@ const struct iommu_ops intel_iommu_ops = { > > .dev_disable_feat = intel_iommu_dev_disable_feat, > > .is_attach_deferred = > > intel_iommu_is_attach_deferred, .pgsize_bitmap = > > INTEL_IOMMU_PGSIZES, +#ifdef CONFIG_INTEL_IOMMU_SVM > > + .sva_bind_gpasid = intel_svm_bind_gpasid, > > + .sva_unbind_gpasid = intel_svm_unbind_gpasid, > > +#endif > > }; > > > > static void quirk_iommu_igfx(struct pci_dev *dev) > > diff --git a/drivers/iommu/intel-svm.c b/drivers/iommu/intel-svm.c > > index a18b02a9709d..ae13a310cf96 100644 > > --- a/drivers/iommu/intel-svm.c > > +++ b/drivers/iommu/intel-svm.c > > @@ -216,6 +216,190 @@ static LIST_HEAD(global_svm_list); > > list_for_each_entry(sdev, &svm->devs, list) \ > > if (dev == sdev->dev) \ > > Add an indent tab please. > looks good. > > > > +int intel_svm_bind_gpasid(struct iommu_domain *domain, > > + struct device *dev, > > + struct iommu_gpasid_bind_data *data) > > +{ > > + struct intel_iommu *iommu = intel_svm_device_to_iommu(dev); > > + struct dmar_domain *ddomain; > > + struct intel_svm_dev *sdev; > > + struct intel_svm *svm; > > + int ret = 0; > > + > > + if (WARN_ON(!iommu) || !data) > > + return -EINVAL; > > + > > + if (data->version != IOMMU_GPASID_BIND_VERSION_1 || > > + data->format != IOMMU_PASID_FORMAT_INTEL_VTD) > > Alignment should match open parenthesis. > > Run "scripts/checkpatch.pl --strict" for all in this patch. I will > ignore others. > it was my editor's setting :), will do. > > + return -EINVAL; > > + > > + if (dev_is_pci(dev)) { > > + /* VT-d supports devices with full 20 bit PASIDs > > only */ > > + if (pci_max_pasids(to_pci_dev(dev)) != PASID_MAX) > > + return -EINVAL; > > + } > > + > > + /* > > + * We only check host PASID range, we have no knowledge to > > check > > + * guest PASID range nor do we use the guest PASID. > > + */ > > + if (data->hpasid <= 0 || data->hpasid >= PASID_MAX) > > + return -EINVAL; > > + > > + ddomain = to_dmar_domain(domain); > > + /* REVISIT: > > + * Sanity check adddress width and paging mode support > > s/adddress/address/g > good catch, I will add the check for paging mode and this comment is no longer needed. > > + * width matching in two dimensions: > > + * 1. paging mode CPU <= IOMMU > > + * 2. address width Guest <= Host. > > + */ > + mutex_lock(&pasid_mutex); > > + svm = ioasid_find(NULL, data->hpasid, NULL); > > + if (IS_ERR(svm)) { > > + ret = PTR_ERR(svm); > > + goto out; > > + } > > A blank line looks better. > true. > > + if (svm) { > > + /* > > + * If we found svm for the PASID, there must be at > > + * least one device bond, otherwise svm should be > > freed. > > + */ > > + BUG_ON(list_empty(&svm->devs)); > > Avoid crashing kernel, use WARN_ON() instead. > > if (WARN_ON(list_empty(&svm->devs))) { > ret = -EINVAL; > goto out; > } > Yeah, WARN_ON is better, should let the kernel continue for easy debug. Though this is an indication of serious problem. > > + > > + for_each_svm_dev(svm, dev) { > > + /* In case of multiple sub-devices of the > > same pdev assigned, we should > > Make line shorter. Not over 80 characters. > > The same for other lines. > sure. > > + * allow multiple bind calls with the same > > PASID and pdev. > > + */ > > + sdev->users++; > > + goto out; > > + } > > I remember I ever pointed this out before. But I forgot how we > addressed it. So forgive me if this has been addressed. > > What if we have a valid bound svm but @dev doesn't belong to it > (a.k.a. @dev not in svm->devs list)? > If we are binding a new device to an existing/active PASID, the code will allocate a new sdev and add that to the svm->devs list. > > + } else { > > + /* We come here when PASID has never been bond to > > a device. */ > > + svm = kzalloc(sizeof(*svm), GFP_KERNEL); > > + if (!svm) { > > + ret = -ENOMEM; > > + goto out; > > + } > > + /* REVISIT: upper layer/VFIO can track host > > process that bind the PASID. > > + * ioasid_set = mm might be sufficient for vfio to > > check pasid VMM > > + * ownership. > > + */ > > + svm->mm = get_task_mm(current); > > + svm->pasid = data->hpasid; > > + if (data->flags & IOMMU_SVA_GPASID_VAL) { > > + svm->gpasid = data->gpasid; > > + svm->flags |= SVM_FLAG_GUEST_PASID; > > + } > > + ioasid_set_data(data->hpasid, svm); > > + INIT_LIST_HEAD_RCU(&svm->devs); > > + INIT_LIST_HEAD(&svm->list); > > + > > + mmput(svm->mm); > > + } > > A blank line, please. looks good. > > > + sdev = kzalloc(sizeof(*sdev), GFP_KERNEL); > > + if (!sdev) { > > + if (list_empty(&svm->devs)) > > + kfree(svm); > > This is dangerous. This might leave a wild pointer bound with gpasid. > why is that? can you please explain? if the list is empty that means we just allocated the new svm, no users. why can't we free it here? > > + ret = -ENOMEM; > > + goto out; > > + } > > + sdev->dev = dev; > > + sdev->users = 1; > > + > > + /* Set up device context entry for PASID if not enabled > > already */ > > + ret = intel_iommu_enable_pasid(iommu, sdev->dev); > > + if (ret) { > > + dev_err(dev, "Failed to enable PASID > > capability\n"); > > + kfree(sdev); > > + goto out; > > + } > > + > > + /* > > + * For guest bind, we need to set up PASID table entry as > > follows: > > + * - FLPM matches guest paging mode > > + * - turn on nested mode > > + * - SL guest address width matching > > + */ > > + ret = intel_pasid_setup_nested(iommu, > > + dev, > > + (pgd_t *)data->gpgd, > > + data->hpasid, > > + &data->vtd, > > + ddomain, > > + data->addr_width); > > + if (ret) { > > + dev_err(dev, "Failed to set up PASID %llu in > > nested mode, Err %d\n", > > + data->hpasid, ret); > > This error handling is insufficient. You should at least: > > 1. free sdev already done below > 2. if list_empty(&svm->devs) > unbound the svm from gpasid > free svm > yes, agreed. > The same for above error handling. Add a branch for error recovery at > the end of function might help here. > not sure which code is the same as above? could you point it out? > > + kfree(sdev); > > + goto out; > > + } > > + svm->flags |= SVM_FLAG_GUEST_MODE; > > + > > + init_rcu_head(&sdev->rcu); > > + list_add_rcu(&sdev->list, &svm->devs); > > + out: > > + mutex_unlock(&pasid_mutex); > > + return ret; > > +} > > + > > +int intel_svm_unbind_gpasid(struct device *dev, int pasid) > > +{ > > + struct intel_svm_dev *sdev; > > + struct intel_iommu *iommu; > > + struct intel_svm *svm; > > + int ret = -EINVAL; > > + > > + mutex_lock(&pasid_mutex); > > + iommu = intel_svm_device_to_iommu(dev); > > + if (!iommu) > > + goto out; > > Make it symmetrical with bind function. > > if (WARN_ON(!iommu)) > goto out; > sounds good. > > + > > + svm = ioasid_find(NULL, pasid, NULL); > > + if (IS_ERR_OR_NULL(svm)) { > > + ret = PTR_ERR(svm); > > If svm == NULL, this function will return success. This is not > expected, right? > good catch, will fix. > > + goto out; > > + } > > + > > + for_each_svm_dev(svm, dev) { > > + ret = 0; > > + sdev->users--; > > + if (!sdev->users) { > > + list_del_rcu(&sdev->list); > > + intel_pasid_tear_down_entry(iommu, dev, > > svm->pasid); > > + /* TODO: Drain in flight PRQ for the PASID > > since it > > + * may get reused soon, we don't want to > > + * confuse with its previous life. > > + * intel_svm_drain_prq(dev, pasid); > > + */ > > + kfree_rcu(sdev, rcu); > > + > > + if (list_empty(&svm->devs)) { > > + list_del(&svm->list); > > + kfree(svm); > > + /* > > + * We do not free PASID here until > > explicit call > > + * from VFIO to free. The PASID > > life cycle > > + * management is largely tied to > > VFIO management > > + * of assigned device life cycles. > > In case of > > + * guest exit without a explicit > > free PASID call, > > + * the responsibility lies in VFIO > > layer to free > > + * the PASIDs allocated for the > > guest. > > + * For security reasons, VFIO has > > to track the > > + * PASID ownership per guest > > anyway to ensure > > + * that PASID allocated by one > > guest cannot be > > + * used by another. > > + */ > > + ioasid_set_data(pasid, NULL); > > Exchange order. First unbind svm from gpasid and then free svm. > I am not following, aren't we already doing free svm after unbind? please explain. > > + } > > + } > > + break; > > + } > > + out: > > + mutex_unlock(&pasid_mutex); > > + > > + return ret; > > +} > > + > > int intel_svm_bind_mm(struct device *dev, int *pasid, int flags, > > struct svm_dev_ops *ops) { > > struct intel_iommu *iommu = > > intel_svm_device_to_iommu(dev); diff --git > > a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h index > > 3dba6ad3e9ad..6c74c71b1ebf 100644 --- a/include/linux/intel-iommu.h > > +++ b/include/linux/intel-iommu.h > > @@ -673,7 +673,9 @@ int intel_iommu_enable_pasid(struct intel_iommu > > *iommu, struct device *dev); int intel_svm_init(struct intel_iommu > > *iommu); extern int intel_svm_enable_prq(struct intel_iommu *iommu); > > extern int intel_svm_finish_prq(struct intel_iommu *iommu); > > - > > +extern int intel_svm_bind_gpasid(struct iommu_domain *domain, > > + struct device *dev, struct iommu_gpasid_bind_data > > *data); +extern int intel_svm_unbind_gpasid(struct device *dev, int > > pasid); struct svm_dev_ops; > > > > struct intel_svm_dev { > > @@ -690,9 +692,13 @@ struct intel_svm_dev { > > struct intel_svm { > > struct mmu_notifier notifier; > > struct mm_struct *mm; > > + > > struct intel_iommu *iommu; > > int flags; > > int pasid; > > + int gpasid; /* Guest PASID in case of vSVA bind with > > non-identity host > > + * to guest PASID mapping. > > + */ > > struct list_head devs; > > struct list_head list; > > }; > > diff --git a/include/linux/intel-svm.h b/include/linux/intel-svm.h > > index 94f047a8a845..a2c189ad0b01 100644 > > --- a/include/linux/intel-svm.h > > +++ b/include/linux/intel-svm.h > > @@ -44,6 +44,23 @@ struct svm_dev_ops { > > * do such IOTLB flushes automatically. > > */ > > #define SVM_FLAG_SUPERVISOR_MODE (1<<1) > > +/* > > + * The SVM_FLAG_GUEST_MODE flag is used when a guest process bind > > to a device. > > + * In this case the mm_struct is in the guest kernel or userspace, > > its life > > + * cycle is managed by VMM and VFIO layer. For IOMMU driver, this > > API provides > > + * means to bind/unbind guest CR3 with PASIDs allocated for a > > device. > > + */ > > +#define SVM_FLAG_GUEST_MODE (1<<2) > > How about keeping this aligned with top by adding a tab? > sounds good. > BIT macro is preferred. Hence, make it BIT(1), BIT(2), BIT(3) is > preferred. > I know, but the existing mainline code is not using BIT, so I wanted to keep coding style consistent. Perhaps a separate cleanup patch will do later. > > +/* > > + * The SVM_FLAG_GUEST_PASID flag is used when a guest has its own > > PASID space, > > + * which requires guest and host PASID translation at both > > directions. We keep > > + * track of guest PASID in order to provide lookup service to > > device drivers. > > + * One such example is a physical function (PF) driver that > > supports mediated > > + * device (mdev) assignment. Guest programming of mdev > > configuration space can > > + * only be done with guest PASID, therefore PF driver needs to > > find the matching > > + * host PASID to program the real hardware. > > + */ > > +#define SVM_FLAG_GUEST_PASID (1<<3) > > Ditto. > > Best regards, > baolu [Jacob Pan] _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
