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SubjectRe: [PATCH v3 1/7] iommu/amd: Warn when found inconsistency EFR mask
On Wed, Jun 22, 2022 at 12:11:25PM -0500, Suravee Suthikulpanit wrote:
> #ifdef CONFIG_IRQ_REMAP
> +/*
> + * Iterate through all the IOMMUs to verify if the specified
> + * EFR bitmask of IOMMU feature are set.
> + * Warn and return false if found inconsistency.
> + */
> static bool check_feature_on_all_iommus(u64 mask)
> {
> bool ret = false;
> struct amd_iommu *iommu;
>
> for_each_iommu(iommu) {
> - ret = iommu_feature(iommu, mask);
> - if (!ret)
> + bool tmp = iommu_feature(iommu, mask);
> +
> + if ((ret != tmp) &&
> + !list_is_first(&iommu->list, &amd_iommu_list)) {
> + pr_err(FW_BUG "Found inconsistent EFR mask (%#llx) on iommu%d (%04x:%02x:%02x.%01x).\n",
> + mask, iommu->index, iommu->pci_seg->id, PCI_BUS_NUM(iommu->devid),
> + PCI_SLOT(iommu->devid), PCI_FUNC(iommu->devid));
> return false;
> + }
> + ret = tmp;

It is better to implement this by introducing a global feature mask,
which represents the minial set of features supported by any IOMMU in
the system.

The warning is then something like:

if ((global_feature_mask & iommu_features) != global_feature_mask)
pr_warn(...);

This also makes the global variable to track SNP support obsolete.

Regards,

Joerg

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