From: Jacob Pan <jacob.jun.pan@linux.intel.com>
To: Jean-Philippe Brucker <jean-philippe@linaro.org>
Cc: "Tian, Kevin" <kevin.tian@intel.com>,
Raj Ashok <ashok.raj@intel.com>,
David Woodhouse <dwmw2@infradead.org>,
iommu@lists.linux-foundation.org,
LKML <linux-kernel@vger.kernel.org>,
Alex Williamson <alex.williamson@redhat.com>,
Jean-Philippe Brucker <jean-philippe@linaro.com>,
Jonathan Cameron <jic23@kernel.org>
Subject: Re: [PATCH v2 3/4] iommu/ioasid: Add custom allocators
Date: Wed, 2 Oct 2019 10:20:44 -0700 [thread overview]
Message-ID: <20191002102044.6ed3ad56@jacob-builder> (raw)
In-Reply-To: <20191002161825.GA626133@lophozonia>
On Wed, 2 Oct 2019 18:18:25 +0200
Jean-Philippe Brucker <jean-philippe@linaro.org> wrote:
> Hi Jacob,
>
> I have four tiny comments below but the patch looks great otherwise,
> no major concern from me.
>
> On Sat, Sep 21, 2019 at 05:07:49PM -0700, Jacob Pan wrote:
> > +/*
> > + * struct ioasid_allocator_data - Internal data structure to hold
> > information
> > + * about an allocator. There are two types of allocators:
> > + *
> > + * - Default allocator always has its own XArray to track the
> > IOASIDs allocated.
> > + * - Custom allocators may share allocation helpers with different
> > private data.
> > + * Custom allocators that share the same helper functions also
> > share the same
> > + * XArray.
> > + * Rules:
> > + * 1. Default allocator is always available, not dynamically
> > registered. This is
> > + * to prevent race conditions with early boot code that want to
> > register
> > + * custom allocators or allocate IOASIDs.
> > + * 2. Custom allocators take precedence over the default allocator.
> > + * 3. When all custom allocators sharing the same helper functions
> > are
> > + * unregistered (e.g. due to hotplug), all outstanding IOASIDs
> > must be
> > + * freed. Otherwise, outstand IOASIDs will be lost and
> > orphaned.
>
> outstanding
>
> [...]
> > ioasid_t ioasid_alloc(struct ioasid_set *set, ioasid_t min,
> > ioasid_t max, void *private)
> > {
> > - ioasid_t id;
> > struct ioasid_data *data;
> > + void *adata;
> > + ioasid_t id;
>
> nit: changing the location of id could be in patch 2/4.
>
will do.
> > - data = kzalloc(sizeof(*data), GFP_KERNEL);
> > + data = kzalloc(sizeof(*data), GFP_ATOMIC);
>
> I don't think that one needs to be GFP_ATOMIC. Otherwise it should
> probably be done from the start, by patch 2/4.
>
I was thinking since we are making this API usable in atomic context,
we need to use GFP_ATOMIC and spinlock throughout the code. I agree it
should be moved to 2/4.
> > if (!data)
> > return INVALID_IOASID;
> >
> > data->set = set;
> > data->private = private;
> >
> > - if (xa_alloc(&ioasid_xa, &id, data, XA_LIMIT(min, max),
> > GFP_KERNEL)) {
> > - pr_err("Failed to alloc ioasid from %d to %d\n",
> > min, max);
> > + /*
> > + * Custom allocator needs allocator data to perform
> > platform specific
> > + * operations.
> > + */
> > + spin_lock(&ioasid_allocator_lock);
> > + adata = active_allocator->flags &
> > IOASID_ALLOCATOR_CUSTOM ? active_allocator->ops->pdata : data;
> > + id = active_allocator->ops->alloc(min, max, adata);
> > + if (id == INVALID_IOASID) {
> > + pr_err("Failed ASID allocation %lu\n",
> > active_allocator->flags);
> > + goto exit_free;
> > + }
> > +
> > + if ((active_allocator->flags & IOASID_ALLOCATOR_CUSTOM) &&
> > + xa_alloc(&active_allocator->xa, &id, data,
> > XA_LIMIT(id, id), GFP_ATOMIC)) {
>
> nit: aligning at the "if (" would make this block more readable.
>
sounds good. I need to change my editor :)
> > + /* Custom allocator needs framework to store and
> > track allocation results */
> > + pr_err("Failed to alloc ioasid from %d\n", id);
> > + active_allocator->ops->free(id,
> > active_allocator->ops->pdata); goto exit_free;
> > }
>
> Thanks,
> Jean
[Jacob Pan]
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next prev parent reply other threads:[~2019-10-02 17:17 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-22 0:07 [PATCH v2 0/4] User API for nested shared virtual address (SVA) Jacob Pan
2019-09-22 0:07 ` [PATCH v2 1/4] iommu: Introduce cache_invalidate API Jacob Pan
2019-09-22 0:07 ` [PATCH v2 2/4] iommu: Add I/O ASID allocator Jacob Pan
2019-09-22 1:45 ` kbuild test robot
2019-09-22 0:07 ` [PATCH v2 3/4] iommu/ioasid: Add custom allocators Jacob Pan
2019-10-02 16:18 ` Jean-Philippe Brucker
2019-10-02 17:20 ` Jacob Pan [this message]
2019-09-22 0:07 ` [PATCH v2 4/4] iommu: Introduce guest PASID bind function Jacob Pan
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