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

["Suthikulpanit, Suravee" <suravee.suthikulpanit@amd.com>]

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