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Message-ID: <0a0f33b8-e3d8-3d29-ca71-552f1875bc62@linux.intel.com>
Date: Wed, 23 Oct 2019 10:21:51 +0800
From: Lu Baolu <baolu.lu@...ux.intel.com>
To: "Raj, Ashok" <ashok.raj@...el.com>,
Jacob Pan <jacob.jun.pan@...ux.intel.com>
Cc: baolu.lu@...ux.intel.com, iommu@...ts.linux-foundation.org,
LKML <linux-kernel@...r.kernel.org>,
Joerg Roedel <joro@...tes.org>,
David Woodhouse <dwmw2@...radead.org>,
Alex Williamson <alex.williamson@...hat.com>,
Jean-Philippe Brucker <jean-philippe@...aro.com>,
Yi Liu <yi.l.liu@...el.com>,
"Tian, Kevin" <kevin.tian@...el.com>,
Christoph Hellwig <hch@...radead.org>,
Jonathan Cameron <jic23@...nel.org>,
Eric Auger <eric.auger@...hat.com>
Subject: Re: [PATCH v6 02/10] iommu/vt-d: Add custom allocator for IOASID
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@...ux.intel.com>
>> Signed-off-by: Liu, Yi L <yi.l.liu@...el.com>
>> Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.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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