| Message ID | 20200430143424.2787566-18-jean-philippe@linaro.org (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Headers | show |
| Series | iommu: Shared Virtual Addressing for SMMUv3 | expand |
Hi Jean, A couple question on how SMMU handles CD.v and translation disable. On Thu, 30 Apr 2020 16:34:16 +0200 Jean-Philippe Brucker <jean-philippe@linaro.org> wrote: > The sva_bind() function allows devices to access process address > spaces using a PASID (aka SSID). > > (1) bind() allocates or gets an existing MMU notifier tied to the > (domain, mm) pair. Each mm gets one PASID. > > (2) Any change to the address space calls invalidate_range() which > sends ATC invalidations (in a subsequent patch). > > (3) When the process address space dies, the release() notifier > disables the CD to allow reclaiming the page tables. Since release() > has to be light we do not instruct device drivers to stop DMA here, > we just ignore incoming page faults. > > To avoid any event 0x0a print (C_BAD_CD) we disable translation > without clearing CD.V. PCIe Translation Requests and Page Requests > are silently denied. Don't clear the R bit because the S bit can't > be cleared when STALL_MODEL==0b10 (forced), and clearing R without > clearing S is useless. Faulting transactions will stall and will > be aborted by the IOPF handler. > > (4) After stopping DMA, the device driver releases the bond by calling > unbind(). We release the MMU notifier, free the PASID and the > bond. > > Three structures keep track of bonds: > * arm_smmu_bond: one per (device, mm) pair, the handle returned to the > device driver for a bind() request. > * arm_smmu_mmu_notifier: one per (domain, mm) pair, deals with ATS/TLB > invalidations and clearing the context descriptor on mm exit. > * arm_smmu_ctx_desc: one per mm, holds the pinned ASID and pgd. > > Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org> > --- > v5->v6: > * Implement bind() directly instead of going through io_mm_ops > * Don't clear S and R bits in step (3), it doesn't work with > STALL_FORCE. > --- > drivers/iommu/Kconfig | 1 + > drivers/iommu/arm-smmu-v3.c | 256 > +++++++++++++++++++++++++++++++++++- 2 files changed, 253 > insertions(+), 4 deletions(-) > > diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig > index 1e64ee6592e16..f863c4562feeb 100644 > --- a/drivers/iommu/Kconfig > +++ b/drivers/iommu/Kconfig > @@ -432,6 +432,7 @@ config ARM_SMMU_V3 > tristate "ARM Ltd. System MMU Version 3 (SMMUv3) Support" > depends on ARM64 > select IOMMU_API > + select IOMMU_SVA > select IOMMU_IO_PGTABLE_LPAE > select GENERIC_MSI_IRQ_DOMAIN > help > diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c > index c7942d0540599..00e5b69bb81a5 100644 > --- a/drivers/iommu/arm-smmu-v3.c > +++ b/drivers/iommu/arm-smmu-v3.c > @@ -24,6 +24,7 @@ > #include <linux/iopoll.h> > #include <linux/module.h> > #include <linux/mmu_context.h> > +#include <linux/mmu_notifier.h> > #include <linux/msi.h> > #include <linux/of.h> > #include <linux/of_address.h> > @@ -36,6 +37,7 @@ > #include <linux/amba/bus.h> > > #include "io-pgtable-arm.h" > +#include "iommu-sva.h" > > /* MMIO registers */ > #define ARM_SMMU_IDR0 0x0 > @@ -731,8 +733,31 @@ struct arm_smmu_domain { > > struct list_head devices; > spinlock_t devices_lock; > + > + struct mmu_notifier_ops mn_ops; > }; > > +struct arm_smmu_mmu_notifier { > + struct mmu_notifier mn; > + struct arm_smmu_ctx_desc *cd; > + bool cleared; > + refcount_t refs; > + struct arm_smmu_domain *domain; > +}; > + > +#define mn_to_smmu(mn) container_of(mn, struct > arm_smmu_mmu_notifier, mn) + > +struct arm_smmu_bond { > + struct iommu_sva sva; > + struct mm_struct *mm; > + struct arm_smmu_mmu_notifier *smmu_mn; > + struct list_head list; > + refcount_t refs; > +}; > + > +#define sva_to_bond(handle) \ > + container_of(handle, struct arm_smmu_bond, sva) > + > struct arm_smmu_option_prop { > u32 opt; > const char *prop; > @@ -742,6 +767,13 @@ static DEFINE_XARRAY_ALLOC1(asid_xa); > static DEFINE_SPINLOCK(contexts_lock); > static DEFINE_MUTEX(arm_smmu_sva_lock); > > +/* > + * When a process dies, DMA is still running but we need to clear > the pgd. If we > + * simply cleared the valid bit from the context descriptor, we'd > get event 0x0a > + * which are not recoverable. > + */ > +static struct arm_smmu_ctx_desc invalid_cd = { 0 }; > + > static struct arm_smmu_option_prop arm_smmu_options[] = { > { ARM_SMMU_OPT_SKIP_PREFETCH, > "hisilicon,broken-prefetch-cmd" }, { ARM_SMMU_OPT_PAGE0_REGS_ONLY, > "cavium,cn9900-broken-page1-regspace"}, @@ -1652,7 +1684,9 @@ static > int __arm_smmu_write_ctx_desc(struct arm_smmu_domain *smmu_domain, > * (2) Install a secondary CD, for SID+SSID traffic. > * (3) Update ASID of a CD. Atomically write the first 64 > bits of the > * CD, then invalidate the old entry and mappings. > - * (4) Remove a secondary CD. > + * (4) Quiesce the context without clearing the valid bit. > Disable > + * translation, and ignore any translation fault. > + * (5) Remove a secondary CD. > */ > u64 val; > bool cd_live; > @@ -1669,8 +1703,10 @@ static int __arm_smmu_write_ctx_desc(struct > arm_smmu_domain *smmu_domain, val = le64_to_cpu(cdptr[0]); > cd_live = !!(val & CTXDESC_CD_0_V); > > - if (!cd) { /* (4) */ > + if (!cd) { /* (5) */ > val = 0; > + } else if (cd == &invalid_cd) { /* (4) */ > + val |= CTXDESC_CD_0_TCR_EPD0; > } else if (cd_live) { /* (3) */ > val &= ~CTXDESC_CD_0_ASID; > val |= FIELD_PREP(CTXDESC_CD_0_ASID, cd->asid); > @@ -1883,7 +1919,6 @@ static struct arm_smmu_ctx_desc > *arm_smmu_share_asid(u16 asid) return NULL; > } > > -__maybe_unused > static struct arm_smmu_ctx_desc *arm_smmu_alloc_shared_cd(struct > mm_struct *mm) { > u16 asid; > @@ -1976,7 +2011,6 @@ static struct arm_smmu_ctx_desc > *arm_smmu_alloc_shared_cd(struct mm_struct *mm) return ERR_PTR(ret); > } > > -__maybe_unused > static void arm_smmu_free_shared_cd(struct arm_smmu_ctx_desc *cd) > { > if (arm_smmu_free_asid(cd)) { > @@ -2611,6 +2645,8 @@ static bool arm_smmu_capable(enum iommu_cap cap) > } > } > > +static struct mmu_notifier_ops arm_smmu_mmu_notifier_ops; > + > static struct iommu_domain *arm_smmu_domain_alloc(unsigned type) > { > struct arm_smmu_domain *smmu_domain; > @@ -2638,6 +2674,7 @@ static struct iommu_domain > *arm_smmu_domain_alloc(unsigned type) > mutex_init(&smmu_domain->init_mutex); > INIT_LIST_HEAD(&smmu_domain->devices); > spin_lock_init(&smmu_domain->devices_lock); > + smmu_domain->mn_ops = arm_smmu_mmu_notifier_ops; > > return &smmu_domain->domain; > } > @@ -3118,6 +3155,208 @@ arm_smmu_iova_to_phys(struct iommu_domain > *domain, dma_addr_t iova) return ops->iova_to_phys(ops, iova); > } > > +static struct mmu_notifier *arm_smmu_mmu_notifier_alloc(struct > mm_struct *mm) +{ > + struct arm_smmu_mmu_notifier *smmu_mn; > + > + smmu_mn = kzalloc(sizeof(*smmu_mn), GFP_KERNEL); > + if (!smmu_mn) > + return ERR_PTR(-ENOMEM); > + > + smmu_mn->cd = arm_smmu_alloc_shared_cd(mm); > + if (IS_ERR(smmu_mn->cd)) { > + void *ptr = ERR_CAST(smmu_mn->cd); > + > + kfree(smmu_mn); > + return ptr; > + } > + refcount_set(&smmu_mn->refs, 1); > + > + return &smmu_mn->mn; > +} > + > +static void arm_smmu_mmu_notifier_free(struct mmu_notifier *mn) > +{ > + struct arm_smmu_mmu_notifier *smmu_mn = mn_to_smmu(mn); > + > + arm_smmu_free_shared_cd(smmu_mn->cd); > + kfree(smmu_mn); > +} > + > +static void arm_smmu_mm_invalidate_range(struct mmu_notifier *mn, > + struct mm_struct *mm, > + unsigned long start, > unsigned long end) +{ > + /* TODO: invalidate ATS */ > +} > + > +static void arm_smmu_mm_release(struct mmu_notifier *mn, struct > mm_struct *mm) +{ > + struct arm_smmu_mmu_notifier *smmu_mn = mn_to_smmu(mn); > + struct arm_smmu_domain *smmu_domain; > + > + mutex_lock(&arm_smmu_sva_lock); > + if (smmu_mn->cleared) { > + mutex_unlock(&arm_smmu_sva_lock); > + return; > + } > + > + smmu_domain = smmu_mn->domain; > + > + /* > + * DMA may still be running. Keep the cd valid but disable > + * translation, so that new events will still result in > stall. > + */ Does "disable translation" also disable translated requests? I guess release is called after tlb invalidate range, so assuming no more devTLB left to generate translated request? > + arm_smmu_write_ctx_desc(smmu_domain, mm->pasid, &invalid_cd); > + > + arm_smmu_tlb_inv_asid(smmu_domain->smmu, smmu_mn->cd->asid); > + /* TODO: invalidate ATS */ > + If mm release is called after tlb invalidate range, is it still necessary to invalidate again? > + smmu_mn->cleared = true; > + mutex_unlock(&arm_smmu_sva_lock); > +} > + > +static struct mmu_notifier_ops arm_smmu_mmu_notifier_ops = { > + .alloc_notifier = arm_smmu_mmu_notifier_alloc, > + .free_notifier = arm_smmu_mmu_notifier_free, > + .invalidate_range = arm_smmu_mm_invalidate_range, > + .release = arm_smmu_mm_release, > +}; > + > +static struct iommu_sva * > +__arm_smmu_sva_bind(struct device *dev, struct mm_struct *mm) > +{ > + int ret; > + ioasid_t pasid; > + struct mmu_notifier *mn; > + struct arm_smmu_bond *bond; > + struct arm_smmu_mmu_notifier *smmu_mn; > + struct arm_smmu_master *master = dev_iommu_priv_get(dev); > + struct iommu_domain *domain = iommu_get_domain_for_dev(dev); > + struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain); > + > + if (!master || !master->sva_enabled) > + return ERR_PTR(-ENODEV); > + > + /* If bind() was already called for this (dev, mm) pair, > reuse it. */ > + list_for_each_entry(bond, &master->bonds, list) { > + if (bond->mm == mm) { > + refcount_inc(&bond->refs); > + return &bond->sva; > + } > + } > + > + mn = mmu_notifier_get(&smmu_domain->mn_ops, mm); > + if (IS_ERR(mn)) > + return ERR_CAST(mn); > + > + smmu_mn = mn_to_smmu(mn); > + if (smmu_mn->domain) > + refcount_inc(&smmu_mn->refs); > + > + bond = kzalloc(sizeof(*bond), GFP_KERNEL); > + if (!bond) { > + ret = -ENOMEM; > + goto err_put_mn; > + } > + > + /* Allocate a PASID for this mm if necessary */ > + pasid = iommu_sva_alloc_pasid(mm, 1, (1U << > master->ssid_bits) - 1); > + if (pasid == INVALID_IOASID) { > + ret = -ENOSPC; > + goto err_free_bond; > + } > + bond->mm = mm; > + bond->sva.dev = dev; > + bond->smmu_mn = smmu_mn; > + refcount_set(&bond->refs, 1); > + > + ret = arm_smmu_write_ctx_desc(smmu_domain, mm->pasid, > smmu_mn->cd); > + if (ret) > + goto err_free_pasid; > + > + bond->sva.dev = dev; > + list_add(&bond->list, &master->bonds); > + smmu_mn->domain = smmu_domain; > + return &bond->sva; > + > +err_free_pasid: > + iommu_sva_free_pasid(mm); > +err_free_bond: > + kfree(bond); > +err_put_mn: > + refcount_dec(&smmu_mn->refs); > + mmu_notifier_put(mn); > + return ERR_PTR(ret); > +} > + > +static void __arm_smmu_sva_unbind(struct iommu_sva *handle) > +{ > + struct arm_smmu_mmu_notifier *smmu_mn; > + struct arm_smmu_bond *bond = sva_to_bond(handle); > + struct iommu_domain *domain = > iommu_get_domain_for_dev(handle->dev); > + struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain); > + > + if (!refcount_dec_and_test(&bond->refs)) > + return; > + > + list_del(&bond->list); > + > + smmu_mn = bond->smmu_mn; > + /* > + * This is redundant as the MMU notifier already counts > refs, but frees > + * the bond in a RCU callback which cannot sleep. We have > much cleaning > + * to do and we hold all the right locks, so duplicate the > refcounting. > + */ > + if (refcount_dec_and_test(&smmu_mn->refs)) { > + arm_smmu_write_ctx_desc(smmu_domain, > bond->mm->pasid, NULL); + > + /* > + * If we went through clear(), we've already > invalidated, and no > + * new TLB entry can have been formed. > + */ > + if (!smmu_mn->cleared) { > + arm_smmu_tlb_inv_asid(smmu_domain->smmu, > + smmu_mn->cd->asid); > + /* TODO: invalidate ATS */ > + } > + } > + > + iommu_sva_free_pasid(bond->mm); > + kfree(bond); > + mmu_notifier_put(&smmu_mn->mn); > +} > + > +static struct iommu_sva * > +arm_smmu_sva_bind(struct device *dev, struct mm_struct *mm, void > *drvdata) +{ > + struct iommu_sva *handle; > + struct iommu_domain *domain = iommu_get_domain_for_dev(dev); > + struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain); > + > + if (smmu_domain->stage != ARM_SMMU_DOMAIN_S1) > + return ERR_PTR(-EINVAL); > + > + mutex_lock(&arm_smmu_sva_lock); > + handle = __arm_smmu_sva_bind(dev, mm); > + mutex_unlock(&arm_smmu_sva_lock); > + return handle; > +} > + > +static void arm_smmu_sva_unbind(struct iommu_sva *handle) > +{ > + mutex_lock(&arm_smmu_sva_lock); > + __arm_smmu_sva_unbind(handle); > + mutex_unlock(&arm_smmu_sva_lock); > +} > + > +static int arm_smmu_sva_get_pasid(struct iommu_sva *handle) > +{ > + struct arm_smmu_bond *bond = sva_to_bond(handle); > + > + return bond->mm->pasid; > +} > + > static struct platform_driver arm_smmu_driver; > > static > @@ -3426,6 +3665,12 @@ static int arm_smmu_dev_disable_sva(struct > device *dev) master->sva_enabled = false; > mutex_unlock(&arm_smmu_sva_lock); > > + /* > + * Since the MMU notifier ops are held in the domain, it is > not safe to > + * free the domain until all MMU notifiers are freed. > + */ > + mmu_notifier_synchronize(); > + > return 0; > } > > @@ -3482,6 +3727,9 @@ static struct iommu_ops arm_smmu_ops = { > .dev_feat_enabled = arm_smmu_dev_feature_enabled, > .dev_enable_feat = arm_smmu_dev_enable_feature, > .dev_disable_feat = arm_smmu_dev_disable_feature, > + .sva_bind = arm_smmu_sva_bind, > + .sva_unbind = arm_smmu_sva_unbind, > + .sva_get_pasid = arm_smmu_sva_get_pasid, > .pgsize_bitmap = -1UL, /* Restricted during > device attach */ }; > [Jacob Pan]
> @@ -432,6 +432,7 @@ config ARM_SMMU_V3 > tristate "ARM Ltd. System MMU Version 3 (SMMUv3) Support" > depends on ARM64 > select IOMMU_API > + select IOMMU_SVA > select IOMMU_IO_PGTABLE_LPAE > select GENERIC_MSI_IRQ_DOMAIN Doesn't this need to select MMU_NOTIFIER now? > + struct mmu_notifier_ops mn_ops; Note: not a pointer. > + /* If bind() was already called for this (dev, mm) pair, reuse it. */ > + list_for_each_entry(bond, &master->bonds, list) { > + if (bond->mm == mm) { > + refcount_inc(&bond->refs); > + return &bond->sva; > + } > + } > + > + mn = mmu_notifier_get(&smmu_domain->mn_ops, mm); > + if (IS_ERR(mn)) > + return ERR_CAST(mn); Which seems to be to avoid mmu_notifier_get reusing notifiers registered by other arm_smmu_master instance right? Either you could just use plain old mmu_notifier_register to avoid the reuse. Or we could enhance the mmu_notifier_get to pass a private oaque instance ID pointer, which is checked in addition to the ops, and you could probably kill off the bonds list and lookup.
On Fri, May 01, 2020 at 05:15:52AM -0700, Christoph Hellwig wrote: > > @@ -432,6 +432,7 @@ config ARM_SMMU_V3 > > tristate "ARM Ltd. System MMU Version 3 (SMMUv3) Support" > > depends on ARM64 > > select IOMMU_API > > + select IOMMU_SVA > > select IOMMU_IO_PGTABLE_LPAE > > select GENERIC_MSI_IRQ_DOMAIN > > Doesn't this need to select MMU_NOTIFIER now? > > > + struct mmu_notifier_ops mn_ops; > > Note: not a pointer. > > > + /* If bind() was already called for this (dev, mm) pair, reuse it. */ > > + list_for_each_entry(bond, &master->bonds, list) { > > + if (bond->mm == mm) { > > + refcount_inc(&bond->refs); > > + return &bond->sva; > > + } > > + } I also would like it if searching for mms in linked lists was not necessary, this is kind of the point of 'get' Is this a side effect of the earlier remark to get rid of the linked list inside the notifier? > Or we could enhance the mmu_notifier_get to pass a private > oaque instance ID pointer, which is checked in addition to the ops, > and you could probably kill off the bonds list and lookup. This might be the best option if it can absorb the above search.. Jason
On Fri, May 01, 2020 at 05:15:52AM -0700, Christoph Hellwig wrote: > > @@ -432,6 +432,7 @@ config ARM_SMMU_V3 > > tristate "ARM Ltd. System MMU Version 3 (SMMUv3) Support" > > depends on ARM64 > > select IOMMU_API > > + select IOMMU_SVA > > select IOMMU_IO_PGTABLE_LPAE > > select GENERIC_MSI_IRQ_DOMAIN > > Doesn't this need to select MMU_NOTIFIER now? Yes, will fix > > + struct mmu_notifier_ops mn_ops; > > Note: not a pointer. > > > + /* If bind() was already called for this (dev, mm) pair, reuse it. */ > > + list_for_each_entry(bond, &master->bonds, list) { > > + if (bond->mm == mm) { > > + refcount_inc(&bond->refs); > > + return &bond->sva; > > + } > > + } > > + > > + mn = mmu_notifier_get(&smmu_domain->mn_ops, mm); > > + if (IS_ERR(mn)) > > + return ERR_CAST(mn); > > Which seems to be to avoid mmu_notifier_get reusing notifiers registered > by other arm_smmu_master instance right? Yes, although I'm registering a single mmu notifier per (domain, mm) pair, not (master, mm), because the SMMU driver keeps one set of PASID tables per IOMMU domain. > Either you could just use plain old mmu_notifier_register to avoid > the reuse. Or we could enhance the mmu_notifier_get to pass a private > oaque instance ID pointer, which is checked in addition to the ops, > and you could probably kill off the bonds list and lookup. Going back to mmu_notifier_register() seems better for now. I don't want to change the core APIs just for this driver, because it's likely to change again when more hardware starts appearing and we optimize it. Thanks, Jean
On Fri, May 01, 2020 at 09:55:13AM -0300, Jason Gunthorpe wrote: > On Fri, May 01, 2020 at 05:15:52AM -0700, Christoph Hellwig wrote: > > > @@ -432,6 +432,7 @@ config ARM_SMMU_V3 > > > tristate "ARM Ltd. System MMU Version 3 (SMMUv3) Support" > > > depends on ARM64 > > > select IOMMU_API > > > + select IOMMU_SVA > > > select IOMMU_IO_PGTABLE_LPAE > > > select GENERIC_MSI_IRQ_DOMAIN > > > > Doesn't this need to select MMU_NOTIFIER now? > > > > > + struct mmu_notifier_ops mn_ops; > > > > Note: not a pointer. > > > > > + /* If bind() was already called for this (dev, mm) pair, reuse it. */ > > > + list_for_each_entry(bond, &master->bonds, list) { > > > + if (bond->mm == mm) { > > > + refcount_inc(&bond->refs); > > > + return &bond->sva; > > > + } > > > + } > > I also would like it if searching for mms in linked lists was not > necessary, this is kind of the point of 'get' > > Is this a side effect of the earlier remark to get rid of the linked > list inside the notifier? > > > Or we could enhance the mmu_notifier_get to pass a private > > oaque instance ID pointer, which is checked in addition to the ops, > > and you could probably kill off the bonds list and lookup. > > This might be the best option if it can absorb the above search.. It wouldn't, the above search is separate. I currently register the MMU notifier on (IOMMU domain, mm). The (dev, mm) search above is to follow the iommu_sva_bind_device() API doc, that states we should return the same handle for a given (dev, mm) pair. Thanks, Jean
On Thu, Apr 30, 2020 at 02:16:17PM -0700, Jacob Pan wrote: > > +static void arm_smmu_mm_invalidate_range(struct mmu_notifier *mn, > > + struct mm_struct *mm, > > + unsigned long start, > > unsigned long end) +{ > > + /* TODO: invalidate ATS */ > > +} > > + > > +static void arm_smmu_mm_release(struct mmu_notifier *mn, struct > > mm_struct *mm) +{ > > + struct arm_smmu_mmu_notifier *smmu_mn = mn_to_smmu(mn); > > + struct arm_smmu_domain *smmu_domain; > > + > > + mutex_lock(&arm_smmu_sva_lock); > > + if (smmu_mn->cleared) { > > + mutex_unlock(&arm_smmu_sva_lock); > > + return; > > + } > > + > > + smmu_domain = smmu_mn->domain; > > + > > + /* > > + * DMA may still be running. Keep the cd valid but disable > > + * translation, so that new events will still result in > > stall. > > + */ > Does "disable translation" also disable translated requests? No it doesn't disable translated requests, it only prevents the SMMU from accessing the pgd. > I guess > release is called after tlb invalidate range, so assuming no more > devTLB left to generate translated request? I'm counting on the invalidate below (here a TODO, implemented in next patch) to drop all devTLB entries. After that invalidate, the device: * issues a Translation Request, returns with R=W=0 because we disabled translation (and it isn't present in the SMMU TLB). * issues a Page Request, returns with InvalidRequest because mmget_not_zero() fails. > > > + arm_smmu_write_ctx_desc(smmu_domain, mm->pasid, &invalid_cd); > > + > > + arm_smmu_tlb_inv_asid(smmu_domain->smmu, smmu_mn->cd->asid); > > + /* TODO: invalidate ATS */ > > + > If mm release is called after tlb invalidate range, is it still > necessary to invalidate again? No, provided all mappings from the address space are unmapped and invalidated. I'll double check, but in my tests invalidate range didn't seem to be called for all mappings on mm exit, so I believe we do need this. Thanks, Jean
On Mon, 4 May 2020 18:43:51 +0200 Jean-Philippe Brucker <jean-philippe@linaro.org> wrote: > On Thu, Apr 30, 2020 at 02:16:17PM -0700, Jacob Pan wrote: > > > +static void arm_smmu_mm_invalidate_range(struct mmu_notifier *mn, > > > + struct mm_struct *mm, > > > + unsigned long start, > > > unsigned long end) +{ > > > + /* TODO: invalidate ATS */ > > > +} > > > + > > > +static void arm_smmu_mm_release(struct mmu_notifier *mn, struct > > > mm_struct *mm) +{ > > > + struct arm_smmu_mmu_notifier *smmu_mn = mn_to_smmu(mn); > > > + struct arm_smmu_domain *smmu_domain; > > > + > > > + mutex_lock(&arm_smmu_sva_lock); > > > + if (smmu_mn->cleared) { > > > + mutex_unlock(&arm_smmu_sva_lock); > > > + return; > > > + } > > > + > > > + smmu_domain = smmu_mn->domain; > > > + > > > + /* > > > + * DMA may still be running. Keep the cd valid but > > > disable > > > + * translation, so that new events will still result in > > > stall. > > > + */ > > Does "disable translation" also disable translated requests? > > No it doesn't disable translated requests, it only prevents the SMMU > from accessing the pgd. > OK. same as VT-d. > > I guess > > release is called after tlb invalidate range, so assuming no more > > devTLB left to generate translated request? > > I'm counting on the invalidate below (here a TODO, implemented in next > patch) to drop all devTLB entries. After that invalidate, the device: > * issues a Translation Request, returns with R=W=0 because we disabled > translation (and it isn't present in the SMMU TLB). > * issues a Page Request, returns with InvalidRequest because > mmget_not_zero() fails. > Same flow. Thanks for the explanation. > > > > > + arm_smmu_write_ctx_desc(smmu_domain, mm->pasid, > > > &invalid_cd); + > > > + arm_smmu_tlb_inv_asid(smmu_domain->smmu, > > > smmu_mn->cd->asid); > > > + /* TODO: invalidate ATS */ > > > + > > If mm release is called after tlb invalidate range, is it still > > necessary to invalidate again? > > No, provided all mappings from the address space are unmapped and > invalidated. I'll double check, but in my tests invalidate range > didn't seem to be called for all mappings on mm exit, so I believe we > do need this. > I think it is safe to invalidate again. There was a concern that mm release may delete IOMMU driver from the notification list and miss tlb invalidate range. I had a hard time to confirm that with ftrace while killing a process, many lost events. > Thanks, > Jean > [Jacob Pan]
On Mon, May 04, 2020 at 01:47:23PM -0700, Jacob Pan wrote: > > > > + arm_smmu_write_ctx_desc(smmu_domain, mm->pasid, > > > > &invalid_cd); + > > > > + arm_smmu_tlb_inv_asid(smmu_domain->smmu, > > > > smmu_mn->cd->asid); > > > > + /* TODO: invalidate ATS */ > > > > + > > > If mm release is called after tlb invalidate range, is it still > > > necessary to invalidate again? > > > > No, provided all mappings from the address space are unmapped and > > invalidated. I'll double check, but in my tests invalidate range > > didn't seem to be called for all mappings on mm exit, so I believe we > > do need this. > > > I think it is safe to invalidate again. There was a concern that mm > release may delete IOMMU driver from the notification list and miss tlb > invalidate range. I had a hard time to confirm that with ftrace while > killing a process, many lost events. > If it helps, I have a test that generates small DMA transactions on a SMMU model. This is the trace for a job on a 8kB mmap'd buffer: smmu_bind_alloc: dev=0000:00:03.0 pasid=1 dev_fault: IOMMU:0000:00:03.0 type=2 reason=0 addr=0x0000ffff860e6000 pasid=1 group=74 flags=3 prot=2 dev_page_response: IOMMU:0000:00:03.0 code=0 pasid=1 group=74 dev_fault: IOMMU:0000:00:03.0 type=2 reason=0 addr=0x0000ffff860e7000 pasid=1 group=143 flags=3 prot=2 dev_page_response: IOMMU:0000:00:03.0 code=0 pasid=1 group=143 smmu_mm_invalidate: pasid=1 start=0xffff860e6000 end=0xffff860e8000 smmu_mm_invalidate: pasid=1 start=0xffff860e6000 end=0xffff860e8000 smmu_mm_invalidate: pasid=1 start=0xffff860e8000 end=0xffff860ea000 smmu_mm_invalidate: pasid=1 start=0xffff860e8000 end=0xffff860ea000 smmu_unbind_free: dev=0000:00:03.0 pasid=1 And this is the same job, but the process immediately kills itself after launching it. smmu_bind_alloc: dev=0000:00:03.0 pasid=1 dev_fault: IOMMU:0000:00:03.0 type=2 reason=0 addr=0x0000ffffb9d15000 pasid=1 group=259 flags=3 prot=2 smmu_mm_release: pasid=1 dev_page_response: IOMMU:0000:00:03.0 code=0 pasid=1 group=259 dev_fault: IOMMU:0000:00:03.0 type=2 reason=0 addr=0x0000ffffb9d15000 pasid=1 group=383 flags=3 prot=2 dev_page_response: IOMMU:0000:00:03.0 code=1 pasid=1 group=383 smmu_unbind_free: dev=0000:00:03.0 pasid=1 We don't get any invalidate_range notification in this case. Thanks, Jean
On Tue, 5 May 2020 11:15:31 +0200 Jean-Philippe Brucker <jean-philippe@linaro.org> wrote: > On Mon, May 04, 2020 at 01:47:23PM -0700, Jacob Pan wrote: > > > > > + arm_smmu_write_ctx_desc(smmu_domain, mm->pasid, > > > > > &invalid_cd); + > > > > > + arm_smmu_tlb_inv_asid(smmu_domain->smmu, > > > > > smmu_mn->cd->asid); > > > > > + /* TODO: invalidate ATS */ > > > > > + > > > > If mm release is called after tlb invalidate range, is it still > > > > necessary to invalidate again? > > > > > > No, provided all mappings from the address space are unmapped and > > > invalidated. I'll double check, but in my tests invalidate range > > > didn't seem to be called for all mappings on mm exit, so I > > > believe we do need this. > > > > > I think it is safe to invalidate again. There was a concern that mm > > release may delete IOMMU driver from the notification list and miss > > tlb invalidate range. I had a hard time to confirm that with ftrace > > while killing a process, many lost events. > > > > If it helps, I have a test that generates small DMA transactions on a > SMMU model. This is the trace for a job on a 8kB mmap'd buffer: > > smmu_bind_alloc: dev=0000:00:03.0 pasid=1 > dev_fault: IOMMU:0000:00:03.0 type=2 reason=0 > addr=0x0000ffff860e6000 pasid=1 group=74 flags=3 prot=2 > dev_page_response: IOMMU:0000:00:03.0 code=0 pasid=1 group=74 > dev_fault: IOMMU:0000:00:03.0 type=2 reason=0 addr=0x0000ffff860e7000 > pasid=1 group=143 flags=3 prot=2 dev_page_response: > IOMMU:0000:00:03.0 code=0 pasid=1 group=143 smmu_mm_invalidate: > pasid=1 start=0xffff860e6000 end=0xffff860e8000 smmu_mm_invalidate: > pasid=1 start=0xffff860e6000 end=0xffff860e8000 smmu_mm_invalidate: > pasid=1 start=0xffff860e8000 end=0xffff860ea000 smmu_mm_invalidate: > pasid=1 start=0xffff860e8000 end=0xffff860ea000 smmu_unbind_free: > dev=0000:00:03.0 pasid=1 > > And this is the same job, but the process immediately kills itself > after launching it. > > smmu_bind_alloc: dev=0000:00:03.0 pasid=1 > dev_fault: IOMMU:0000:00:03.0 type=2 reason=0 > addr=0x0000ffffb9d15000 pasid=1 group=259 flags=3 prot=2 > smmu_mm_release: pasid=1 dev_page_response: IOMMU:0000:00:03.0 code=0 > pasid=1 group=259 dev_fault: IOMMU:0000:00:03.0 type=2 reason=0 > addr=0x0000ffffb9d15000 pasid=1 group=383 flags=3 prot=2 > dev_page_response: IOMMU:0000:00:03.0 code=1 pasid=1 group=383 > smmu_unbind_free: dev=0000:00:03.0 pasid=1 > > We don't get any invalidate_range notification in this case. > Thanks for the confirmation. We do need to invalidate here. > Thanks, > Jean [Jacob Pan]
diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig index 1e64ee6592e16..f863c4562feeb 100644 --- a/drivers/iommu/Kconfig +++ b/drivers/iommu/Kconfig @@ -432,6 +432,7 @@ config ARM_SMMU_V3 tristate "ARM Ltd. System MMU Version 3 (SMMUv3) Support" depends on ARM64 select IOMMU_API + select IOMMU_SVA select IOMMU_IO_PGTABLE_LPAE select GENERIC_MSI_IRQ_DOMAIN help diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c index c7942d0540599..00e5b69bb81a5 100644 --- a/drivers/iommu/arm-smmu-v3.c +++ b/drivers/iommu/arm-smmu-v3.c @@ -24,6 +24,7 @@ #include <linux/iopoll.h> #include <linux/module.h> #include <linux/mmu_context.h> +#include <linux/mmu_notifier.h> #include <linux/msi.h> #include <linux/of.h> #include <linux/of_address.h> @@ -36,6 +37,7 @@ #include <linux/amba/bus.h> #include "io-pgtable-arm.h" +#include "iommu-sva.h" /* MMIO registers */ #define ARM_SMMU_IDR0 0x0 @@ -731,8 +733,31 @@ struct arm_smmu_domain { struct list_head devices; spinlock_t devices_lock; + + struct mmu_notifier_ops mn_ops; }; +struct arm_smmu_mmu_notifier { + struct mmu_notifier mn; + struct arm_smmu_ctx_desc *cd; + bool cleared; + refcount_t refs; + struct arm_smmu_domain *domain; +}; + +#define mn_to_smmu(mn) container_of(mn, struct arm_smmu_mmu_notifier, mn) + +struct arm_smmu_bond { + struct iommu_sva sva; + struct mm_struct *mm; + struct arm_smmu_mmu_notifier *smmu_mn; + struct list_head list; + refcount_t refs; +}; + +#define sva_to_bond(handle) \ + container_of(handle, struct arm_smmu_bond, sva) + struct arm_smmu_option_prop { u32 opt; const char *prop; @@ -742,6 +767,13 @@ static DEFINE_XARRAY_ALLOC1(asid_xa); static DEFINE_SPINLOCK(contexts_lock); static DEFINE_MUTEX(arm_smmu_sva_lock); +/* + * When a process dies, DMA is still running but we need to clear the pgd. If we + * simply cleared the valid bit from the context descriptor, we'd get event 0x0a + * which are not recoverable. + */ +static struct arm_smmu_ctx_desc invalid_cd = { 0 }; + static struct arm_smmu_option_prop arm_smmu_options[] = { { ARM_SMMU_OPT_SKIP_PREFETCH, "hisilicon,broken-prefetch-cmd" }, { ARM_SMMU_OPT_PAGE0_REGS_ONLY, "cavium,cn9900-broken-page1-regspace"}, @@ -1652,7 +1684,9 @@ static int __arm_smmu_write_ctx_desc(struct arm_smmu_domain *smmu_domain, * (2) Install a secondary CD, for SID+SSID traffic. * (3) Update ASID of a CD. Atomically write the first 64 bits of the * CD, then invalidate the old entry and mappings. - * (4) Remove a secondary CD. + * (4) Quiesce the context without clearing the valid bit. Disable + * translation, and ignore any translation fault. + * (5) Remove a secondary CD. */ u64 val; bool cd_live; @@ -1669,8 +1703,10 @@ static int __arm_smmu_write_ctx_desc(struct arm_smmu_domain *smmu_domain, val = le64_to_cpu(cdptr[0]); cd_live = !!(val & CTXDESC_CD_0_V); - if (!cd) { /* (4) */ + if (!cd) { /* (5) */ val = 0; + } else if (cd == &invalid_cd) { /* (4) */ + val |= CTXDESC_CD_0_TCR_EPD0; } else if (cd_live) { /* (3) */ val &= ~CTXDESC_CD_0_ASID; val |= FIELD_PREP(CTXDESC_CD_0_ASID, cd->asid); @@ -1883,7 +1919,6 @@ static struct arm_smmu_ctx_desc *arm_smmu_share_asid(u16 asid) return NULL; } -__maybe_unused static struct arm_smmu_ctx_desc *arm_smmu_alloc_shared_cd(struct mm_struct *mm) { u16 asid; @@ -1976,7 +2011,6 @@ static struct arm_smmu_ctx_desc *arm_smmu_alloc_shared_cd(struct mm_struct *mm) return ERR_PTR(ret); } -__maybe_unused static void arm_smmu_free_shared_cd(struct arm_smmu_ctx_desc *cd) { if (arm_smmu_free_asid(cd)) { @@ -2611,6 +2645,8 @@ static bool arm_smmu_capable(enum iommu_cap cap) } } +static struct mmu_notifier_ops arm_smmu_mmu_notifier_ops; + static struct iommu_domain *arm_smmu_domain_alloc(unsigned type) { struct arm_smmu_domain *smmu_domain; @@ -2638,6 +2674,7 @@ static struct iommu_domain *arm_smmu_domain_alloc(unsigned type) mutex_init(&smmu_domain->init_mutex); INIT_LIST_HEAD(&smmu_domain->devices); spin_lock_init(&smmu_domain->devices_lock); + smmu_domain->mn_ops = arm_smmu_mmu_notifier_ops; return &smmu_domain->domain; } @@ -3118,6 +3155,208 @@ arm_smmu_iova_to_phys(struct iommu_domain *domain, dma_addr_t iova) return ops->iova_to_phys(ops, iova); } +static struct mmu_notifier *arm_smmu_mmu_notifier_alloc(struct mm_struct *mm) +{ + struct arm_smmu_mmu_notifier *smmu_mn; + + smmu_mn = kzalloc(sizeof(*smmu_mn), GFP_KERNEL); + if (!smmu_mn) + return ERR_PTR(-ENOMEM); + + smmu_mn->cd = arm_smmu_alloc_shared_cd(mm); + if (IS_ERR(smmu_mn->cd)) { + void *ptr = ERR_CAST(smmu_mn->cd); + + kfree(smmu_mn); + return ptr; + } + refcount_set(&smmu_mn->refs, 1); + + return &smmu_mn->mn; +} + +static void arm_smmu_mmu_notifier_free(struct mmu_notifier *mn) +{ + struct arm_smmu_mmu_notifier *smmu_mn = mn_to_smmu(mn); + + arm_smmu_free_shared_cd(smmu_mn->cd); + kfree(smmu_mn); +} + +static void arm_smmu_mm_invalidate_range(struct mmu_notifier *mn, + struct mm_struct *mm, + unsigned long start, unsigned long end) +{ + /* TODO: invalidate ATS */ +} + +static void arm_smmu_mm_release(struct mmu_notifier *mn, struct mm_struct *mm) +{ + struct arm_smmu_mmu_notifier *smmu_mn = mn_to_smmu(mn); + struct arm_smmu_domain *smmu_domain; + + mutex_lock(&arm_smmu_sva_lock); + if (smmu_mn->cleared) { + mutex_unlock(&arm_smmu_sva_lock); + return; + } + + smmu_domain = smmu_mn->domain; + + /* + * DMA may still be running. Keep the cd valid but disable + * translation, so that new events will still result in stall. + */ + arm_smmu_write_ctx_desc(smmu_domain, mm->pasid, &invalid_cd); + + arm_smmu_tlb_inv_asid(smmu_domain->smmu, smmu_mn->cd->asid); + /* TODO: invalidate ATS */ + + smmu_mn->cleared = true; + mutex_unlock(&arm_smmu_sva_lock); +} + +static struct mmu_notifier_ops arm_smmu_mmu_notifier_ops = { + .alloc_notifier = arm_smmu_mmu_notifier_alloc, + .free_notifier = arm_smmu_mmu_notifier_free, + .invalidate_range = arm_smmu_mm_invalidate_range, + .release = arm_smmu_mm_release, +}; + +static struct iommu_sva * +__arm_smmu_sva_bind(struct device *dev, struct mm_struct *mm) +{ + int ret; + ioasid_t pasid; + struct mmu_notifier *mn; + struct arm_smmu_bond *bond; + struct arm_smmu_mmu_notifier *smmu_mn; + struct arm_smmu_master *master = dev_iommu_priv_get(dev); + struct iommu_domain *domain = iommu_get_domain_for_dev(dev); + struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain); + + if (!master || !master->sva_enabled) + return ERR_PTR(-ENODEV); + + /* If bind() was already called for this (dev, mm) pair, reuse it. */ + list_for_each_entry(bond, &master->bonds, list) { + if (bond->mm == mm) { + refcount_inc(&bond->refs); + return &bond->sva; + } + } + + mn = mmu_notifier_get(&smmu_domain->mn_ops, mm); + if (IS_ERR(mn)) + return ERR_CAST(mn); + + smmu_mn = mn_to_smmu(mn); + if (smmu_mn->domain) + refcount_inc(&smmu_mn->refs); + + bond = kzalloc(sizeof(*bond), GFP_KERNEL); + if (!bond) { + ret = -ENOMEM; + goto err_put_mn; + } + + /* Allocate a PASID for this mm if necessary */ + pasid = iommu_sva_alloc_pasid(mm, 1, (1U << master->ssid_bits) - 1); + if (pasid == INVALID_IOASID) { + ret = -ENOSPC; + goto err_free_bond; + } + bond->mm = mm; + bond->sva.dev = dev; + bond->smmu_mn = smmu_mn; + refcount_set(&bond->refs, 1); + + ret = arm_smmu_write_ctx_desc(smmu_domain, mm->pasid, smmu_mn->cd); + if (ret) + goto err_free_pasid; + + bond->sva.dev = dev; + list_add(&bond->list, &master->bonds); + smmu_mn->domain = smmu_domain; + return &bond->sva; + +err_free_pasid: + iommu_sva_free_pasid(mm); +err_free_bond: + kfree(bond); +err_put_mn: + refcount_dec(&smmu_mn->refs); + mmu_notifier_put(mn); + return ERR_PTR(ret); +} + +static void __arm_smmu_sva_unbind(struct iommu_sva *handle) +{ + struct arm_smmu_mmu_notifier *smmu_mn; + struct arm_smmu_bond *bond = sva_to_bond(handle); + struct iommu_domain *domain = iommu_get_domain_for_dev(handle->dev); + struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain); + + if (!refcount_dec_and_test(&bond->refs)) + return; + + list_del(&bond->list); + + smmu_mn = bond->smmu_mn; + /* + * This is redundant as the MMU notifier already counts refs, but frees + * the bond in a RCU callback which cannot sleep. We have much cleaning + * to do and we hold all the right locks, so duplicate the refcounting. + */ + if (refcount_dec_and_test(&smmu_mn->refs)) { + arm_smmu_write_ctx_desc(smmu_domain, bond->mm->pasid, NULL); + + /* + * If we went through clear(), we've already invalidated, and no + * new TLB entry can have been formed. + */ + if (!smmu_mn->cleared) { + arm_smmu_tlb_inv_asid(smmu_domain->smmu, + smmu_mn->cd->asid); + /* TODO: invalidate ATS */ + } + } + + iommu_sva_free_pasid(bond->mm); + kfree(bond); + mmu_notifier_put(&smmu_mn->mn); +} + +static struct iommu_sva * +arm_smmu_sva_bind(struct device *dev, struct mm_struct *mm, void *drvdata) +{ + struct iommu_sva *handle; + struct iommu_domain *domain = iommu_get_domain_for_dev(dev); + struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain); + + if (smmu_domain->stage != ARM_SMMU_DOMAIN_S1) + return ERR_PTR(-EINVAL); + + mutex_lock(&arm_smmu_sva_lock); + handle = __arm_smmu_sva_bind(dev, mm); + mutex_unlock(&arm_smmu_sva_lock); + return handle; +} + +static void arm_smmu_sva_unbind(struct iommu_sva *handle) +{ + mutex_lock(&arm_smmu_sva_lock); + __arm_smmu_sva_unbind(handle); + mutex_unlock(&arm_smmu_sva_lock); +} + +static int arm_smmu_sva_get_pasid(struct iommu_sva *handle) +{ + struct arm_smmu_bond *bond = sva_to_bond(handle); + + return bond->mm->pasid; +} + static struct platform_driver arm_smmu_driver; static @@ -3426,6 +3665,12 @@ static int arm_smmu_dev_disable_sva(struct device *dev) master->sva_enabled = false; mutex_unlock(&arm_smmu_sva_lock); + /* + * Since the MMU notifier ops are held in the domain, it is not safe to + * free the domain until all MMU notifiers are freed. + */ + mmu_notifier_synchronize(); + return 0; } @@ -3482,6 +3727,9 @@ static struct iommu_ops arm_smmu_ops = { .dev_feat_enabled = arm_smmu_dev_feature_enabled, .dev_enable_feat = arm_smmu_dev_enable_feature, .dev_disable_feat = arm_smmu_dev_disable_feature, + .sva_bind = arm_smmu_sva_bind, + .sva_unbind = arm_smmu_sva_unbind, + .sva_get_pasid = arm_smmu_sva_get_pasid, .pgsize_bitmap = -1UL, /* Restricted during device attach */ };
The sva_bind() function allows devices to access process address spaces using a PASID (aka SSID). (1) bind() allocates or gets an existing MMU notifier tied to the (domain, mm) pair. Each mm gets one PASID. (2) Any change to the address space calls invalidate_range() which sends ATC invalidations (in a subsequent patch). (3) When the process address space dies, the release() notifier disables the CD to allow reclaiming the page tables. Since release() has to be light we do not instruct device drivers to stop DMA here, we just ignore incoming page faults. To avoid any event 0x0a print (C_BAD_CD) we disable translation without clearing CD.V. PCIe Translation Requests and Page Requests are silently denied. Don't clear the R bit because the S bit can't be cleared when STALL_MODEL==0b10 (forced), and clearing R without clearing S is useless. Faulting transactions will stall and will be aborted by the IOPF handler. (4) After stopping DMA, the device driver releases the bond by calling unbind(). We release the MMU notifier, free the PASID and the bond. Three structures keep track of bonds: * arm_smmu_bond: one per (device, mm) pair, the handle returned to the device driver for a bind() request. * arm_smmu_mmu_notifier: one per (domain, mm) pair, deals with ATS/TLB invalidations and clearing the context descriptor on mm exit. * arm_smmu_ctx_desc: one per mm, holds the pinned ASID and pgd. Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org> --- v5->v6: * Implement bind() directly instead of going through io_mm_ops * Don't clear S and R bits in step (3), it doesn't work with STALL_FORCE. --- drivers/iommu/Kconfig | 1 + drivers/iommu/arm-smmu-v3.c | 256 +++++++++++++++++++++++++++++++++++- 2 files changed, 253 insertions(+), 4 deletions(-)