linux-kernel - Re: [PATCH v1 06/13] iommufd: Implement sw

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <Z6ufIbqkMqyMZFwY@Asurada-Nvidia>
Date: Tue, 11 Feb 2025 11:04:01 -0800
From: Nicolin Chen <nicolinc@...dia.com>
To: Jason Gunthorpe <jgg@...dia.com>
CC: <kevin.tian@...el.com>, <tglx@...utronix.de>, <maz@...nel.org>,
	<joro@...tes.org>, <will@...nel.org>, <robin.murphy@....com>,
	<shuah@...nel.org>, <iommu@...ts.linux.dev>, <linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <linux-kselftest@...r.kernel.org>,
	<eric.auger@...hat.com>, <baolu.lu@...ux.intel.com>, <yi.l.liu@...el.com>,
	<yury.norov@...il.com>, <jacob.pan@...ux.microsoft.com>,
	<patches@...ts.linux.dev>
Subject: Re: [PATCH v1 06/13] iommufd: Implement sw_msi support natively

On Tue, Feb 11, 2025 at 02:16:20PM -0400, Jason Gunthorpe wrote:
> On Sat, Feb 08, 2025 at 01:02:39AM -0800, Nicolin Chen wrote:
> 
> > +static struct iommufd_attach_handle *
> > +iommu_group_get_iommufd_handle(struct iommu_group *group)
> > +{
> > +	struct iommu_attach_handle *handle;
> > +
> > +	handle = iommu_attach_handle_get(group, IOMMU_NO_PASID, 0);
> > +	if (IS_ERR(handle))
> > +		return NULL;
> > +	return to_iommufd_handle(handle);
> > +}
> > +
> > +/*
> > + * Called by the irq code if the platform translates the MSI address through the
> > + * IOMMU. msi_addr is the physical address of the MSI page. iommufd will
> > + * allocate a fd global iova for the physical page that is the same on all
> > + * domains and devices.
> > + */
> > +#ifdef CONFIG_IRQ_MSI_IOMMU
> > +int iommufd_sw_msi(struct iommu_domain *domain, struct msi_desc *desc,
> > +		   phys_addr_t msi_addr)
> > +{
> > +	struct device *dev = msi_desc_to_dev(desc);
> > +	struct iommufd_hwpt_paging *hwpt_paging;
> > +	struct iommufd_attach_handle *handle;
> > +	struct iommufd_sw_msi_map *msi_map;
> > +	struct iommufd_ctx *ictx;
> > +	unsigned long iova;
> > +	int rc;
> > +
> > +	handle = iommu_group_get_iommufd_handle(dev->iommu_group);
> > +	if (!handle)
> > +		return 0;
> 
> I think you should open code this and leave the other function
> alone. The locking rules are different here.
> 
> iommufd_device_get_attach_handle() should be locked under the
> igroup->lock
> 
> While in this context we are locked under the iommu core group mutex.
> 
> A comment will help
> 
> /*
>  * It is safe to call iommu_attach_handle_get() here because the iommu
>  * core code invokes this under the group mutex which also prevents any
>  * change of the attach handle for the duration of this function.
>  */
>  iommu_group_mutex_assert(dev);

Ack. I reverted that part and added this piece.

Thanks
Nicolin