On 11/7/2023 4:08 PM, Borislav Petkov wrote:
static int __init snp_rmptable_init(void)
{
- int family, model;
-
- if (!cpu_feature_enabled(X86_FEATURE_SEV_SNP))
+ if (!amd_iommu_snp_en)
return 0;
We will still need some method to tell the IOMMU driver if SNP
support/feature is disabled by this function, for example, when CPU
family and model is not supported by SNP and we jump to no_snp label.
The reliable way for this to work is to ensure snp_rmptable_init() is
called before IOMMU initialization and then IOMMU initialization depends
on SNP feature flag setup by snp_rmptable_init() to enable SNP support
on IOMMU or not.
If snp_rmptable_init() is called after IOMMU initialization and it
detects an issue with SNP support it will clear the SNP feature but the
IOMMU driver does not get notified about it, therefore,
snp_rmptable_init() should get called before IOMMU initialization or as
part of IOMMU initialization, for example, amd_iommu_enable() calling
snp_rmptable_init() before calling iommu_snp_enable().
Thanks,
Ashish
