Re: [PATCH v2 10/19] iommu/vt-d: Add custom allocator for IOASID

Auger Eric
2019-04-24T17:27:26Z

Hi Jacob,

On 4/24/19 1:31 AM, Jacob Pan wrote:
> When VT-d driver runs in the guest, PASID allocation must be
> performed via virtual command interface. This patch register a
registers
> custom IOASID allocator which takes precedence over the default
> IDR based allocator.
nit: s/IDR based// . It is xarray based now.
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-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
> Signed-off-by: Liu, Yi L <yi.l.liu-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
> Signed-off-by: Jacob Pan <jacob.jun.pan-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
> ---
> drivers/iommu/intel-iommu.c | 58 +++++++++++++++++++++++++++++++++++++++++++++
> include/linux/intel-iommu.h | 2 ++
> 2 files changed, 60 insertions(+)
>
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index d93c4bd..ec6f22d 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -1711,6 +1711,8 @@ 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
> }
>
> @@ -4811,6 +4813,46 @@ static int __init platform_optin_force_iommu(void)
> return 1;
> }
>
> +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.
> + */
The above comment does not exactly relate to the check below
> + if (min < PASID_MIN || max > PASID_MAX)
> + return -EINVAL;
> +
> + if (vcmd_alloc_pasid(iommu, &ioasid))
> + return INVALID_IOASID;
> +
> + return ioasid;
> +}
> +
> +static int intel_ioasid_free(ioasid_t ioasid, void *data)
> +{
> + struct iommu_pasid_alloc_info *svm;
> + struct intel_iommu *iommu = data;
> +
> + if (!iommu || !cap_caching_mode(iommu->cap))
> + return -EINVAL;
can !cap_caching_mode(iommu->cap) be true as the allocator only is set
if CM?
> + /*
> + * 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) {
you can avoid using the local svm variable.
> + pr_warn("Freeing unbond IOASID %d\n", ioasid);
unbound
> + return -EBUSY;
-EINVAL?
> + }
> + vcmd_free_pasid(iommu, ioasid);
> +
> + return 0;
> +}
> +
> int __init intel_iommu_init(void)
> {
> int ret = -ENODEV;
> @@ -4912,6 +4954,22 @@ int __init intel_iommu_init(void)
> "%s", iommu->name);
> iommu_device_set_ops(&iommu->iommu, &intel_iommu_ops);
> iommu_device_register(&iommu->iommu);
> + if (cap_caching_mode(iommu->cap) && sm_supported(iommu)) {
so shouldn't you test VCCAP_REG as well?
> + /*
> + * 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");
registration
> + }
> }
>
> bus_set_iommu(&pci_bus_type, &intel_iommu_ops);
> diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
> index bff907b..c24c8aa 100644
> --- a/include/linux/intel-iommu.h
> +++ b/include/linux/intel-iommu.h
> @@ -31,6 +31,7 @@
> #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>
> @@ -549,6 +550,7 @@ 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 pasid_allocator; /* Custom allocator for PASIDs */
> #endif
> struct q_inval *qi; /* Queued invalidation info */
> u32 *iommu_state; /* Store iommu states between suspend and resume.*/
>

Thanks

Eric