Messages in this thread | | | Subject | Re: [PATCH v2 11/12] x86/mmu: Allocate/free PASID | From | Lu Baolu <> | Date | Mon, 15 Jun 2020 10:13:42 +0800 |
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Hi Fenghua,
On 6/13/20 8:41 AM, Fenghua Yu wrote: > A PASID is allocated for an "mm" the first time any thread attaches > to an SVM capable device. Later device attachments (whether to the same > device or another SVM device) will re-use the same PASID. > > The PASID is freed when the process exits (so no need to keep > reference counts on how many SVM devices are sharing the PASID). > > Signed-off-by: Fenghua Yu <fenghua.yu@intel.com> > Reviewed-by: Tony Luck <tony.luck@intel.com> > --- > v2: > - Define a helper free_bind() to simplify error exit code in bind_mm() > (Thomas) > - Fix a ret error code in bind_mm() (Thomas) > - Change pasid's type from "int" to "unsigned int" to have consistent > pasid type in iommu (Thomas) > - Simplify alloc_pasid() a bit. > > arch/x86/include/asm/iommu.h | 2 + > arch/x86/include/asm/mmu_context.h | 14 ++++ > drivers/iommu/intel/svm.c | 101 +++++++++++++++++++++++++---- > 3 files changed, 105 insertions(+), 12 deletions(-) > > diff --git a/arch/x86/include/asm/iommu.h b/arch/x86/include/asm/iommu.h > index bf1ed2ddc74b..ed41259fe7ac 100644 > --- a/arch/x86/include/asm/iommu.h > +++ b/arch/x86/include/asm/iommu.h > @@ -26,4 +26,6 @@ arch_rmrr_sanity_check(struct acpi_dmar_reserved_memory *rmrr) > return -EINVAL; > } > > +void __free_pasid(struct mm_struct *mm); > + > #endif /* _ASM_X86_IOMMU_H */ > diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h > index 47562147e70b..f8c91ce8c451 100644 > --- a/arch/x86/include/asm/mmu_context.h > +++ b/arch/x86/include/asm/mmu_context.h > @@ -13,6 +13,7 @@ > #include <asm/tlbflush.h> > #include <asm/paravirt.h> > #include <asm/debugreg.h> > +#include <asm/iommu.h> > > extern atomic64_t last_mm_ctx_id; > > @@ -117,9 +118,22 @@ static inline int init_new_context(struct task_struct *tsk, > init_new_context_ldt(mm); > return 0; > } > + > +static inline void free_pasid(struct mm_struct *mm) > +{ > + if (!IS_ENABLED(CONFIG_INTEL_IOMMU_SVM)) > + return; > + > + if (!cpu_feature_enabled(X86_FEATURE_ENQCMD)) > + return; > + > + __free_pasid(mm); > +} > + > static inline void destroy_context(struct mm_struct *mm) > { > destroy_context_ldt(mm); > + free_pasid(mm); > } > > extern void switch_mm(struct mm_struct *prev, struct mm_struct *next, > diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c > index 4e775e12ae52..27dc866b8461 100644 > --- a/drivers/iommu/intel/svm.c > +++ b/drivers/iommu/intel/svm.c > @@ -425,6 +425,53 @@ int intel_svm_unbind_gpasid(struct device *dev, unsigned int pasid) > return ret; > } > > +static void free_bind(struct intel_svm *svm, struct intel_svm_dev *sdev, > + bool new_pasid) > +{ > + if (new_pasid) > + ioasid_free(svm->pasid); > + kfree(svm); > + kfree(sdev); > +} > + > +/* > + * If this mm already has a PASID, use it. Otherwise allocate a new one. > + * Let the caller know if a new PASID is allocated via 'new_pasid'. > + */ > +static int alloc_pasid(struct intel_svm *svm, struct mm_struct *mm, > + unsigned int pasid_max, bool *new_pasid, > + unsigned int flags) > +{ > + unsigned int pasid; > + > + *new_pasid = false; > + > + /* > + * Reuse the PASID if the mm already has a PASID and not a private > + * PASID is requested. > + */ > + if (mm && mm->pasid && !(flags & SVM_FLAG_PRIVATE_PASID)) { > + /* > + * Once a PASID is allocated for this mm, the PASID > + * stays with the mm until the mm is dropped. Reuse > + * the PASID which has been already allocated for the > + * mm instead of allocating a new one. > + */ > + ioasid_set_data(mm->pasid, svm);
How about adding some sanity checks here? For example,
void *p = ioasid_find(NULL, mm->pasid, NULL);
if (!p) ioasid_set_data(mm->pasid, svm); else if (IS_ERR(p) || p != svm) return INVALID_IOSASID;
Best regards, baolu
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