Re: [PATCH v7 04/11] iommu/vt-d: Replace Intel specific PASID allocator with IOASID

Auger Eric
2019-11-12T09:55:06Z

Hi Jacob,

On 11/8/19 11:55 PM, Jacob Pan wrote:
> On Fri, 8 Nov 2019 12:30:31 +0100
> Auger Eric <eric.auger@redhat.com> wrote:
>
>> Hi Jacob,
>>
>> On 10/24/19 9:54 PM, Jacob Pan wrote:
>>> Make use of generic IOASID code to manage PASID allocation,
>>> free, and lookup. Replace Intel specific code.
>>>
>>> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
>>> ---
>>> drivers/iommu/intel-iommu.c | 12 ++++++------
>>> drivers/iommu/intel-pasid.c | 36
>>> ------------------------------------ drivers/iommu/intel-svm.c |
>>> 39 +++++++++++++++++++++++---------------- 3 files changed, 29
>>> insertions(+), 58 deletions(-)
>>>
>>> diff --git a/drivers/iommu/intel-iommu.c
>>> b/drivers/iommu/intel-iommu.c index ced1d89ef977..2ea09b988a23
>>> 100644 --- a/drivers/iommu/intel-iommu.c
>>> +++ b/drivers/iommu/intel-iommu.c
>>> @@ -5311,7 +5311,7 @@ static void auxiliary_unlink_device(struct
>>> dmar_domain *domain, domain->auxd_refcnt--;
>>>
>>> if (!domain->auxd_refcnt && domain->default_pasid > 0)
>>> - intel_pasid_free_id(domain->default_pasid);
>>> + ioasid_free(domain->default_pasid);
>>> }
>>>
>>> static int aux_domain_add_dev(struct dmar_domain *domain,
>>> @@ -5329,10 +5329,10 @@ static int aux_domain_add_dev(struct
>>> dmar_domain *domain, if (domain->default_pasid <= 0) {
>>> int pasid;
>>>
>>> - pasid = intel_pasid_alloc_id(domain, PASID_MIN,
>>> -
>>> pci_max_pasids(to_pci_dev(dev)),
>>> - GFP_KERNEL);
>>> - if (pasid <= 0) {
>>> + /* No private data needed for the default pasid */
>>> + pasid = ioasid_alloc(NULL, PASID_MIN,
>>> pci_max_pasids(to_pci_dev(dev)) - 1,
>>> + NULL);
>>> + if (pasid == INVALID_IOASID) {
>>> pr_err("Can't allocate default pasid\n");
>>> return -ENODEV;
>>> }
>>> @@ -5368,7 +5368,7 @@ static int aux_domain_add_dev(struct
>>> dmar_domain *domain, spin_unlock(&iommu->lock);
>>> spin_unlock_irqrestore(&device_domain_lock, flags);
>>> if (!domain->auxd_refcnt && domain->default_pasid > 0)
>>> - intel_pasid_free_id(domain->default_pasid);
>>> + ioasid_free(domain->default_pasid);
>>>
>>> return ret;
>>> }
>>> diff --git a/drivers/iommu/intel-pasid.c
>>> b/drivers/iommu/intel-pasid.c index d81e857d2b25..e79d680fe300
>>> 100644 --- a/drivers/iommu/intel-pasid.c
>>> +++ b/drivers/iommu/intel-pasid.c
>>> @@ -26,42 +26,6 @@
>>> */
>>> static DEFINE_SPINLOCK(pasid_lock);
>>> u32 intel_pasid_max_id = PASID_MAX;
>>> -static DEFINE_IDR(pasid_idr);
>>> -
>>> -int intel_pasid_alloc_id(void *ptr, int start, int end, gfp_t gfp)
>>> -{
>>> - int ret, min, max;
>>> -
>>> - min = max_t(int, start, PASID_MIN);
>>> - max = min_t(int, end, intel_pasid_max_id);
>>> -
>>> - WARN_ON(in_interrupt());
>>> - idr_preload(gfp);
>>> - spin_lock(&pasid_lock);
>>> - ret = idr_alloc(&pasid_idr, ptr, min, max, GFP_ATOMIC);
>>> - spin_unlock(&pasid_lock);
>>> - idr_preload_end();
>>> -
>>> - return ret;
>>> -}
>>> -
>>> -void intel_pasid_free_id(int pasid)
>>> -{
>>> - spin_lock(&pasid_lock);
>>> - idr_remove(&pasid_idr, pasid);
>>> - spin_unlock(&pasid_lock);
>>> -}
>>> -
>>> -void *intel_pasid_lookup_id(int pasid)
>>> -{
>>> - void *p;
>>> -
>>> - spin_lock(&pasid_lock);
>>> - p = idr_find(&pasid_idr, pasid);
>>> - spin_unlock(&pasid_lock);
>>> -
>>> - return p;
>>> -}
>>>
>>> int vcmd_alloc_pasid(struct intel_iommu *iommu, unsigned int
>>> *pasid) {
>>> diff --git a/drivers/iommu/intel-svm.c b/drivers/iommu/intel-svm.c
>>> index 9b159132405d..a9a7f85a09bc 100644
>>> --- a/drivers/iommu/intel-svm.c
>>> +++ b/drivers/iommu/intel-svm.c
>>> @@ -17,6 +17,7 @@
>>> #include <linux/dmar.h>
>>> #include <linux/interrupt.h>
>>> #include <linux/mm_types.h>
>>> +#include <linux/ioasid.h>
>>> #include <asm/page.h>
>>>
>>> #include "intel-pasid.h"
>>> @@ -318,16 +319,15 @@ int intel_svm_bind_mm(struct device *dev, int
>>> *pasid, int flags, struct svm_dev_ if (pasid_max >
>>> intel_pasid_max_id) pasid_max = intel_pasid_max_id;
>>>
>>> - /* Do not use PASID 0 in caching mode (virtualised
>>> IOMMU) */
>>> - ret = intel_pasid_alloc_id(svm,
>>> - !!cap_caching_mode(iommu->cap),
>>> - pasid_max - 1,
>>> GFP_KERNEL);
>>> - if (ret < 0) {
>>> + /* Do not use PASID 0, reserved for RID to PASID */
>>> + svm->pasid = ioasid_alloc(NULL, PASID_MIN,
>>> + pasid_max - 1, svm);
>> pasid_max -1 is inclusive. whereas max param in intel_pasid_alloc_id()
>> is exclusive right? If you fixed an issue, you can mention it in the
>> commit message.
> yes, i should mention that. intel_pasid_alloc_id() uses IDR which is
> end exclusive. ioasid uses xarray, which is inclusive.
>>> + if (svm->pasid == INVALID_IOASID) {
>>> kfree(svm);>
>>> kfree(sdev);
>>> + ret = ENOSPC;
>> -ENOSPC.
>> Nit: in 2/11 vcmd_alloc_pasid returned -ENOMEM
> yes, it should be -ENOSPC as well.
>
>>> goto out;
>>> }
>>> - svm->pasid = ret;
>>> svm->notifier.ops = &intel_mmuops;
>>> svm->mm = mm;
>>> svm->flags = flags;
>>> @@ -337,7 +337,7 @@ int intel_svm_bind_mm(struct device *dev, int
>>> *pasid, int flags, struct svm_dev_ if (mm) {
>>> ret =
>>> mmu_notifier_register(&svm->notifier, mm); if (ret) {
>>> - intel_pasid_free_id(svm->pasid);
>>> + ioasid_free(svm->pasid);
>>> kfree(svm);
>>> kfree(sdev);
>>> goto out;
>>> @@ -353,7 +353,7 @@ int intel_svm_bind_mm(struct device *dev, int
>>> *pasid, int flags, struct svm_dev_ if (ret) {
>>> if (mm)
>>> mmu_notifier_unregister(&svm->notifier,
>>> mm);
>>> - intel_pasid_free_id(svm->pasid);
>>> + ioasid_free(svm->pasid);
>>> kfree(svm);
>>> kfree(sdev);
>>> goto out;
>>> @@ -401,7 +401,12 @@ int intel_svm_unbind_mm(struct device *dev,
>>> int pasid) if (!iommu)
>>> goto out;
>>>
>>> - svm = intel_pasid_lookup_id(pasid);
>>> + svm = ioasid_find(NULL, pasid, NULL);
>>> + if (IS_ERR(svm)) {
>>> + ret = PTR_ERR(svm);
>>> + goto out;
>>> + }
>>> +
>>> if (!svm)
>>> goto out;
>>>
>>> @@ -423,7 +428,9 @@ int intel_svm_unbind_mm(struct device *dev, int
>>> pasid) kfree_rcu(sdev, rcu);
>>>
>>> if (list_empty(&svm->devs)) {
>>> -
>>> intel_pasid_free_id(svm->pasid);
>>> + /* Clear private data so
>>> that free pass check */> +
>>> ioasid_set_data(svm->pasid, NULL);
>> I don't get the above comment. Why is it needed?
> Having private data associated with an IOASID is an indicator that this
> IOASID is busy. So we have to clear it to signal it is free.
> Actually, I am planning to introduce a refcount per IOASID since there
> will be multiple users of IOASID, e.g. IOMMU driver and KVM. When
> refcount == 0, we can free.
Ah OK I missed that. This is a specificity of the intel custom PASID
allocator, ie intel_ioasid_free and not a generic behavior.

Thanks

Eric
>
>>> + ioasid_free(svm->pasid);
>>> if (svm->mm)
>>> mmu_notifier_unregister(&svm->notifier,
>>> svm->mm);
>>> @@ -458,10 +465,11 @@ int intel_svm_is_pasid_valid(struct device
>>> *dev, int pasid) if (!iommu)
>>> goto out;
>>>
>>> - svm = intel_pasid_lookup_id(pasid);
>>> - if (!svm)
>>> + svm = ioasid_find(NULL, pasid, NULL);
>>> + if (IS_ERR(svm)) {
>>> + ret = PTR_ERR(svm);
>>> goto out;
>>> -
>>> + }
>>> /* init_mm is used in this case */
>>> if (!svm->mm)
>>> ret = 1;
>>> @@ -568,13 +576,12 @@ static irqreturn_t prq_event_thread(int irq,
>>> void *d)
>>> if (!svm || svm->pasid != req->pasid) {
>>> rcu_read_lock();
>>> - svm = intel_pasid_lookup_id(req->pasid);
>>> + svm = ioasid_find(NULL, req->pasid, NULL);
>>> /* It *can't* go away, because the driver
>>> is not permitted
>>> * to unbind the mm while any page faults
>>> are outstanding.
>>> * So we only need RCU to protect the
>>> internal idr code. */ rcu_read_unlock();
>>> -
>>> - if (!svm) {
>>> + if (IS_ERR(svm) || !svm) {
>>> pr_err("%s: Page request for
>>> invalid PASID %d: %08llx %08llx\n", iommu->name, req->pasid,
>>> ((unsigned long long *)req)[0], ((unsigned long long *)req)[1]);
>>>
>> Thanks
>>
>> Eric
>>
>
> [Jacob Pan]