linux-kernel - Re: [PATCH v3 3/7] iommu/vt-d: Always reserve a domain ID for identity setup

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

Message-ID: <20240806170653.GL676757@ziepe.ca>
Date: Tue, 6 Aug 2024 14:06:53 -0300
From: Jason Gunthorpe <jgg@...pe.ca>
To: Lu Baolu <baolu.lu@...ux.intel.com>
Cc: Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
	Robin Murphy <robin.murphy@....com>,
	Kevin Tian <kevin.tian@...el.com>, iommu@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 3/7] iommu/vt-d: Always reserve a domain ID for
 identity setup

On Tue, Aug 06, 2024 at 10:39:37AM +0800, Lu Baolu wrote:
> We will use a global static identity domain. Reserve a static domain ID
> for it.
> 
> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
> ---
>  drivers/iommu/intel/iommu.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index 723ea9f3f501..c019fb3b3e78 100644
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -1440,10 +1440,10 @@ static int iommu_init_domains(struct intel_iommu *iommu)
>  	 * entry for first-level or pass-through translation modes should
>  	 * be programmed with a domain id different from those used for
>  	 * second-level or nested translation. We reserve a domain id for
> -	 * this purpose.
> +	 * this purpose. This domain id is also used for identity domain
> +	 * in legacy mode.
>  	 */
> -	if (sm_supported(iommu))
> -		set_bit(FLPT_DEFAULT_DID, iommu->domain_ids);
> +	set_bit(FLPT_DEFAULT_DID, iommu->domain_ids);

That should probablyturn into an IDA someday, it would likely be more
memory efficient than bitmap_zalloc()

Reviewed-by: Jason Gunthorpe <jgg@...dia.com>

Jason