linux-kernel - Re: [PATCH v5 2/6] iommu/amd: Introduce helper function to update 256-bit DTE

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: <312be452-84ab-4cc8-b468-b6519d9abfa9@amd.com>
Date: Fri, 11 Oct 2024 12:25:32 +0700
From: "Suthikulpanit, Suravee" <suravee.suthikulpanit@....com>
To: Jason Gunthorpe <jgg@...dia.com>
Cc: linux-kernel@...r.kernel.org, iommu@...ts.linux.dev, joro@...tes.org,
 robin.murphy@....com, vasant.hegde@....com, kevin.tian@...el.com,
 jon.grimm@....com, santosh.shukla@....com, pandoh@...gle.com,
 kumaranand@...gle.com
Subject: Re: [PATCH v5 2/6] iommu/amd: Introduce helper function to update
 256-bit DTE



On 10/7/2024 9:06 PM, Jason Gunthorpe wrote:
> On Mon, Oct 07, 2024 at 04:13:49AM +0000, Suravee Suthikulpanit wrote:
>> +static void write_dte_upper128(struct dev_table_entry *ptr, struct dev_table_entry *new)
>> +{
>> +	struct dev_table_entry old = {};
>> +
>> +	do {
>> +		old.data128[1] = ptr->data128[1];
>> +		new->data[2] &= ~DTE_DATA2_INTR_MASK;
>> +		new->data[2] |= old.data[2] & (DTE_DATA2_INTR_MASK | DTE_DATA2_RESV_MASK);
> 
> Why preserve the reserved bits? Shouldn't they be reserved by forced
> to 0? Should have a comment explaining this

You are correct.

>> +static void iommu_flush_dte_sync(struct amd_iommu *iommu, u16 devid)
>> +{
> 
> You might consider re-ordering to avoid the function forward
> declaration.

This will require moving a lot of other functions as well. We will 
consider this in overall clean up later.

Thanks,
Suravee

> Looks fine otherwise
> 
> Jason