Re: [PATCH v9 06/13] iommu/amd: copy old trans table from old kernel

Joerg Roedel
2017-08-04T12:21:21Z

On Tue, Aug 01, 2017 at 07:37:22PM +0800, Baoquan He wrote:
> static void init_device_table_dma(void)
> {
> @@ -2137,9 +2140,49 @@ static void early_enable_iommu(struct amd_iommu *iommu)
> static void early_enable_iommus(void)
> {
> struct amd_iommu *iommu;
> + bool is_pre_disabled = false;
>
> - for_each_iommu(iommu)
> - early_enable_iommu(iommu);
> + for_each_iommu(iommu) {
> + if (!translation_pre_enabled(iommu)) {
> + is_pre_disabled = true;
> + break;
> + }
> + }

I think this could be easier if you make 'is_pre_disabled' a global state
bool variable with reversed meaning and initialize it with 'true'.
Basically

static bool __init amd_iommu_pre_enabled = true;

And set this variable to 'false' when you find a already disabled IOMMU
during initialization. Then you can remove the code above.

> +
> + if (is_pre_disabled) {
> + for_each_iommu(iommu)
> + early_enable_iommu(iommu);

return
}

> + } else {

And remove this to get rid of one indendation level for the code below.

> + pr_warn("Translation is already enabled - trying to copy translation structures\n");
> + if (copy_device_table()) {

Seeing how the return value of copy_device_table() is used, it makes
sense to change its return-type to bool. This way it is also easier to
see which one is the sucess and which one the failure case.