Messages in this thread | | | Subject | Re: [PATCH v6 02/10] iommu/vt-d: Add custom allocator for IOASID | From | Lu Baolu <> | Date | Wed, 23 Oct 2019 10:21:51 +0800 |
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Hi,
On 10/23/19 8:51 AM, Raj, Ashok wrote: > On Tue, Oct 22, 2019 at 04:53:15PM -0700, Jacob Pan wrote: >> When VT-d driver runs in the guest, PASID allocation must be >> performed via virtual command interface. This patch registers a >> custom IOASID allocator which takes precedence over the default >> XArray based allocator. The resulting IOASID allocation will always >> come from the host. This ensures that PASID namespace is system- >> wide. >> >> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> >> Signed-off-by: Liu, Yi L <yi.l.liu@intel.com> >> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com> >> --- >> drivers/iommu/Kconfig | 1 + >> drivers/iommu/intel-iommu.c | 67 +++++++++++++++++++++++++++++++++++++++++++++ >> include/linux/intel-iommu.h | 2 ++ >> 3 files changed, 70 insertions(+) >> >> diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig >> index fd50ddffffbf..961fe5795a90 100644 >> --- a/drivers/iommu/Kconfig >> +++ b/drivers/iommu/Kconfig >> @@ -211,6 +211,7 @@ config INTEL_IOMMU_SVM >> bool "Support for Shared Virtual Memory with Intel IOMMU" >> depends on INTEL_IOMMU && X86 >> select PCI_PASID >> + select IOASID >> select MMU_NOTIFIER >> help >> Shared Virtual Memory (SVM) provides a facility for devices >> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c >> index 3f974919d3bd..3aff0141c522 100644 >> --- a/drivers/iommu/intel-iommu.c >> +++ b/drivers/iommu/intel-iommu.c >> @@ -1706,6 +1706,8 @@ static void free_dmar_iommu(struct intel_iommu *iommu) >> if (ecap_prs(iommu->ecap)) >> intel_svm_finish_prq(iommu); >> } >> + ioasid_unregister_allocator(&iommu->pasid_allocator); >> + >> #endif >> } >> >> @@ -4910,6 +4912,46 @@ static int __init probe_acpi_namespace_devices(void) >> return 0; >> } >> >> +#ifdef CONFIG_INTEL_IOMMU_SVM > > Maybe move them to intel-svm.c instead? that's where the bulk > of the svm support is?
I think this is a generic PASID allocator for guest IOMMU although vSVA is currently the only consumer. Instead of making it SVM specific, I'd like to suggest moving it to intel-pasid.c and replace the @svm parameter with a void * one in intel_ioasid_free().
> >> +static ioasid_t intel_ioasid_alloc(ioasid_t min, ioasid_t max, void *data) >> +{ >> + struct intel_iommu *iommu = data; >> + ioasid_t ioasid; >> + >> + /* >> + * VT-d virtual command interface always uses the full 20 bit >> + * PASID range. Host can partition guest PASID range based on >> + * policies but it is out of guest's control. >> + */ >> + if (min < PASID_MIN || max > PASID_MAX) >> + return INVALID_IOASID; > > What are these PASID_MIN/MAX? Do you check if these are within the > limits supported by the iommu/vIOMMU as its enumerated? >
Is it an invalid request when @max is greater than hardware capability?
Say, the consumer is asking for allocate a PASID within [0, 2^20], while the PASID pool of the allocator is just, say, [4, 2^19] with others reserved for other special usage or due to iommu capability. Instead of returning error, why not just allocating a PASID within [2, 2^19]?
In another word, final allocation range should be Range[allocator supported] & Range[customer specified]. Please correct me if I missed anything.
> >> + >> + if (vcmd_alloc_pasid(iommu, &ioasid)) >> + return INVALID_IOASID; >> + >> + return ioasid; >> +} >> + >> +static void intel_ioasid_free(ioasid_t ioasid, void *data) >> +{ >> + struct iommu_pasid_alloc_info *svm; >> + struct intel_iommu *iommu = data; >> + >> + if (!iommu) >> + return; >> + /* >> + * Sanity check the ioasid owner is done at upper layer, e.g. VFIO >> + * We can only free the PASID when all the devices are unbond. >> + */ >> + svm = ioasid_find(NULL, ioasid, NULL); >> + if (!svm) { >> + pr_warn("Freeing unbond IOASID %d\n", ioasid); >> + return; >> + } >> + vcmd_free_pasid(iommu, ioasid); >> +} >> +#endif >> + >> int __init intel_iommu_init(void) >> { >> int ret = -ENODEV; >> @@ -5020,6 +5062,31 @@ int __init intel_iommu_init(void) >> "%s", iommu->name); >> iommu_device_set_ops(&iommu->iommu, &intel_iommu_ops); >> iommu_device_register(&iommu->iommu); >> +#ifdef CONFIG_INTEL_IOMMU_SVM >> + if (cap_caching_mode(iommu->cap) && sm_supported(iommu)) { > > do you need to check against cap_caching_mode() or ecap_vcmd? > > >> + /* >> + * Register a custom ASID allocator if we are running >> + * in a guest, the purpose is to have a system wide PASID >> + * namespace among all PASID users. >> + * There can be multiple vIOMMUs in each guest but only >> + * one allocator is active. All vIOMMU allocators will >> + * eventually be calling the same host allocator. >> + */ >> + iommu->pasid_allocator.alloc = intel_ioasid_alloc; >> + iommu->pasid_allocator.free = intel_ioasid_free; >> + iommu->pasid_allocator.pdata = (void *)iommu; >> + ret = ioasid_register_allocator(&iommu->pasid_allocator); >> + if (ret) { >> + pr_warn("Custom PASID allocator registeration failed\n"); >> + /* >> + * Disable scalable mode on this IOMMU if there >> + * is no custom allocator. Mixing SM capable vIOMMU >> + * and non-SM vIOMMU are not supported. >> + */ >> + intel_iommu_sm = 0; >> + } >> + } >> +#endif
I think this should also be moved to intel-pasid.c and made it svm independent as a generic pasid allocator for IOMMU running in a vm guest or user level application.
Best regards, baolu
>> } >> >> bus_set_iommu(&pci_bus_type, &intel_iommu_ops); >> diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h >> index eea7468694a7..fb1973a761c1 100644 >> --- a/include/linux/intel-iommu.h >> +++ b/include/linux/intel-iommu.h >> @@ -19,6 +19,7 @@ >> #include <linux/iommu.h> >> #include <linux/io-64-nonatomic-lo-hi.h> >> #include <linux/dmar.h> >> +#include <linux/ioasid.h> >> >> #include <asm/cacheflush.h> >> #include <asm/iommu.h> >> @@ -542,6 +543,7 @@ struct intel_iommu { >> #ifdef CONFIG_INTEL_IOMMU_SVM >> struct page_req_dsc *prq; >> unsigned char prq_name[16]; /* Name for PRQ interrupt */ >> + struct ioasid_allocator_ops pasid_allocator; /* Custom allocator for PASIDs */ >> #endif >> struct q_inval *qi; /* Queued invalidation info */ >> u32 *iommu_state; /* Store iommu states between suspend and resume.*/ >> -- >> 2.7.4 >> >
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