From: Jean-Philippe Brucker <jean-philippe@linaro.org>
To: Zhangfei Gao <zhangfei.gao@linaro.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Arnd Bergmann <arnd@arndb.de>,
Herbert Xu <herbert@gondor.apana.org.au>,
jonathan.cameron@huawei.com, grant.likely@arm.com,
Jerome Glisse <jglisse@redhat.com>,
ilias.apalodimas@linaro.org, francois.ozog@linaro.org,
kenneth-lee-2012@foxmail.com, Wangzhou <wangzhou1@hisilicon.com>,
"haojian . zhuang" <haojian.zhuang@linaro.org>,
guodong.xu@linaro.org, linux-accelerators@lists.ozlabs.org,
linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org,
iommu@lists.linux-foundation.org,
Kenneth Lee <liguozhu@hisilicon.com>,
Zaibo Xu <xuzaibo@huawei.com>
Subject: Re: [PATCH v7 2/3] uacce: add uacce driver
Date: Tue, 5 Nov 2019 12:48:44 +0100 [thread overview]
Message-ID: <20191105114844.GA3648434@lophozonia> (raw)
In-Reply-To: <1572331216-9503-3-git-send-email-zhangfei.gao@linaro.org>
Hi Zhangfei,
Thanks for simplifying this, it's a lot easier to review. I have some
additional comments.
On Tue, Oct 29, 2019 at 02:40:15PM +0800, Zhangfei Gao wrote:
> +static int uacce_sva_exit(struct device *dev, struct iommu_sva *handle,
> + void *data)
> +{
> + struct uacce_device *uacce = data;
> + struct uacce_queue *q;
> +
> + mutex_lock(&uacce->q_lock);
> + list_for_each_entry(q, &uacce->qs, list) {
> + if (q->pid == task_pid_nr(current))
> + uacce_put_queue(q);
This won't work in some cases, because any thread can call __mmput() and
end up here. For example a sibling thread that inherited the queue, or a
workqueue that's executing mmput_async_fn(). In addition I think comparing
PID values is unsafe (see comment in pid.h), we'd need to use the struct
pid if we wanted to do it this way.
But I still believe it would be better to create an uacce_mm structure
that tracks all queues bound to this mm, and pass that to uacce_sva_exit
instead of the uacce_device.
The queue isn't bound to a task, but its address space. With clone() the
address space can be shared between tasks. In addition, whoever has a
queue fd also gets access to this address space. So after a fork() the
child may be able to program the queue to DMA into the parent's address
space, even without CLONE_VM. Users must be aware of this and I think it's
important to explain it very clearly in the UAPI.
[...]
> +static struct uacce_qfile_region *
> +uacce_create_region(struct uacce_queue *q, struct vm_area_struct *vma,
> + enum uacce_qfrt type, unsigned int flags)
> +{
> + struct uacce_device *uacce = q->uacce;
> + struct uacce_qfile_region *qfr;
> + int ret = -ENOMEM;
> +
> + qfr = kzalloc(sizeof(*qfr), GFP_KERNEL);
> + if (!qfr)
> + return ERR_PTR(-ENOMEM);
> +
> + qfr->type = type;
> + qfr->flags = flags;
> +
> + if (vma->vm_flags & VM_READ)
> + qfr->prot |= IOMMU_READ;
qfr->prot and qfr->flags aren't used at the moment, you could remove them.
> +
> + if (vma->vm_flags & VM_WRITE)
> + qfr->prot |= IOMMU_WRITE;
> +
> + if (flags & UACCE_QFRF_SELFMT) {
> + if (!uacce->ops->mmap) {
> + ret = -EINVAL;
> + goto err_with_qfr;
> + }
> +
> + ret = uacce->ops->mmap(q, vma, qfr);
> + if (ret)
> + goto err_with_qfr;
> + return qfr;
> + }
> +
> + return qfr;
> +
> +err_with_qfr:
> + kfree(qfr);
> + return ERR_PTR(ret);
> +}
> +
> +static int uacce_fops_mmap(struct file *filep, struct vm_area_struct *vma)
> +{
> + struct uacce_queue *q = filep->private_data;
> + struct uacce_device *uacce = q->uacce;
> + struct uacce_qfile_region *qfr;
> + enum uacce_qfrt type = 0;
> + unsigned int flags = 0;
> + int ret;
> +
> + if (vma->vm_pgoff < UACCE_QFRT_MAX)
> + type = vma->vm_pgoff;
Otherwise return -EINVAL? type probably shouldn't default to MMIO if it
wasn't explicitly requested by the user.
> +
> + vma->vm_flags |= VM_DONTCOPY | VM_DONTEXPAND | VM_WIPEONFORK;
> + vma->vm_ops = &uacce_vm_ops;
> + vma->vm_private_data = q;
> +
> + mutex_lock(&uacce_mutex);
> +
> + if (q->qfrs[type]) {
> + ret = -EEXIST;
> + goto out_with_lock;
> + }
> +
> + switch (type) {
> + case UACCE_QFRT_MMIO:
> + flags = UACCE_QFRF_SELFMT;
> + break;
> +
> + case UACCE_QFRT_DUS:
> + if (uacce->flags & UACCE_DEV_SVA) {
> + flags = UACCE_QFRF_SELFMT;
I'd simplify this even further by getting rid of the SELFMT flag. It's the
only possibility at the moment.
> + break;
> + }
> + break;
> +
> + default:
> + WARN_ON(&uacce->dev);
WARN_ON(uacce->dev). But shouldn't we instead return -EINVAL here?
UACCE_QFRT_MAX is currently 16, so users can easily trigger this WARN by
passing an invalid value.
[...]
> +void uacce_unregister(struct uacce_device *uacce)
> +{
> + if (!uacce)
> + return;
> +
> + mutex_lock(&uacce->q_lock);
> + if (!list_empty(&uacce->qs)) {
> + struct uacce_queue *q;
> +
> + list_for_each_entry(q, &uacce->qs, list) {
> + uacce_put_queue(q);
The open file descriptor will still exist after this function returns.
Can all fops can be called with a stale queue?
Thanks,
Jean
next prev parent reply other threads:[~2019-11-05 11:48 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-29 6:40 [PATCH v7 0/3] Add uacce module for Accelerator Zhangfei Gao
2019-10-29 6:40 ` [PATCH v7 1/3] uacce: Add documents for uacce Zhangfei Gao
2019-10-31 15:37 ` Jonathan Cameron
2019-10-29 6:40 ` [PATCH v7 2/3] uacce: add uacce driver Zhangfei Gao
2019-10-31 17:13 ` Jonathan Cameron
2019-11-05 7:43 ` zhangfei
2019-11-11 11:19 ` Jonathan Cameron
2019-11-05 11:48 ` Jean-Philippe Brucker [this message]
2019-11-06 8:17 ` zhangfei
2019-11-06 15:32 ` Jean-Philippe Brucker
2019-11-07 13:23 ` zhangfei
2019-11-08 7:48 ` Jean-Philippe Brucker
2019-10-29 6:40 ` [PATCH v7 3/3] crypto: hisilicon - register zip engine to uacce Zhangfei Gao
2019-10-31 17:53 ` Jonathan Cameron
2019-11-05 8:34 ` zhangfei
2019-11-11 11:30 ` Jonathan Cameron
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20191105114844.GA3648434@lophozonia \
--to=jean-philippe@linaro.org \
--cc=arnd@arndb.de \
--cc=francois.ozog@linaro.org \
--cc=grant.likely@arm.com \
--cc=gregkh@linuxfoundation.org \
--cc=guodong.xu@linaro.org \
--cc=haojian.zhuang@linaro.org \
--cc=herbert@gondor.apana.org.au \
--cc=ilias.apalodimas@linaro.org \
--cc=iommu@lists.linux-foundation.org \
--cc=jglisse@redhat.com \
--cc=jonathan.cameron@huawei.com \
--cc=kenneth-lee-2012@foxmail.com \
--cc=liguozhu@hisilicon.com \
--cc=linux-accelerators@lists.ozlabs.org \
--cc=linux-crypto@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=wangzhou1@hisilicon.com \
--cc=xuzaibo@huawei.com \
--cc=zhangfei.gao@linaro.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).