From: Jason Gunthorpe <jgg@nvidia.com>
To: Yi Liu <yi.l.liu@intel.com>
Cc: joro@8bytes.org, kevin.tian@intel.com, baolu.lu@linux.intel.com,
iommu@lists.linux.dev, jacob.pan@linux.microsoft.com,
robin.murphy@arm.com, nicolinc@nvidia.com, will@kernel.org
Subject: Re: [PATCH 2/2] iommu: Swap the order of setting group->pasid_array and __iommu_set_group_pasid()
Date: Mon, 20 Jan 2025 12:13:52 -0400 [thread overview]
Message-ID: <20250120161352.GL5556@nvidia.com> (raw)
In-Reply-To: <20250120030840.4171-3-yi.l.liu@intel.com>
On Sun, Jan 19, 2025 at 07:08:40PM -0800, Yi Liu wrote:
> Following the current order of setting group->pasid_array and
> __iommu_set_group_pasid() in iommu_attach_device_pasid(), PRIs may be
> forwarded to the domain before the attach succeeds. If the attach failed
> in the end, the PRIs on the domain need to be flushed in the caller side.
> Caller can do it, but it can be avoided by swapping the order. This is
> more self-contained.
Can the caller do it? I thought only the driver could manage it?
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 278c4eb8f225..b69bcf559839 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -3376,7 +3376,7 @@ int iommu_attach_device_pasid(struct iommu_domain *domain,
> struct iommu_group *group = dev->iommu_group;
> struct group_device *device;
> const struct iommu_ops *ops;
> - void *xa_entry;
> + void *curr, *xa_entry;
> int ret;
>
> if (!group)
> @@ -3400,6 +3400,16 @@ int iommu_attach_device_pasid(struct iommu_domain *domain,
> }
> }
>
> + curr = xa_load(&group->pasid_array, pasid);
> + if (curr) {
No need for curr
if (xa_load()) {
> @@ -3407,13 +3417,12 @@ int iommu_attach_device_pasid(struct iommu_domain *domain,
> xa_entry = xa_tag_pointer(domain, IOMMU_PASID_ARRAY_DOMAIN);
> }
>
> - ret = xa_insert(&group->pasid_array, pasid, xa_entry, GFP_KERNEL);
> - if (ret)
> - goto out_unlock;
> + curr = xa_store(&group->pasid_array, pasid, handle, GFP_KERNEL);
> + if (curr) {
> + __iommu_remove_group_pasid(group, pasid, domain);
> + ret = xa_err(curr);
curr could be a valid non-error entry, but that
would be a WARN_ON condition due to the above check. Like this:
ret = xa_insert(&group->pasid_array, pasid, xa_entry,GFP_KERNEL);
if (ret) {
WARN_ON(ret == -EBUSY);
goto out_remove;
}
Jason
next prev parent reply other threads:[~2025-01-20 16:13 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-20 3:08 [PATCH 0/2] Two enhancements to iommu_attach_device_pasid() Yi Liu
2025-01-20 3:08 ` [PATCH 1/2] iommu: Store either domain or handle in group->pasid_array Yi Liu
2025-01-20 5:55 ` Tian, Kevin
2025-01-20 15:55 ` Jason Gunthorpe
2025-01-21 2:02 ` Baolu Lu
2025-01-21 7:22 ` Yi Liu
2025-01-20 3:08 ` [PATCH 2/2] iommu: Swap the order of setting group->pasid_array and __iommu_set_group_pasid() Yi Liu
2025-01-20 5:58 ` Tian, Kevin
2025-01-20 6:57 ` Yi Liu
2025-01-20 16:13 ` Jason Gunthorpe [this message]
2025-01-21 9:27 ` Yi Liu
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=20250120161352.GL5556@nvidia.com \
--to=jgg@nvidia.com \
--cc=baolu.lu@linux.intel.com \
--cc=iommu@lists.linux.dev \
--cc=jacob.pan@linux.microsoft.com \
--cc=joro@8bytes.org \
--cc=kevin.tian@intel.com \
--cc=nicolinc@nvidia.com \
--cc=robin.murphy@arm.com \
--cc=will@kernel.org \
--cc=yi.l.liu@intel.com \
/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