On Fri, Dec 10, 2021 at 11:52:28AM -0800, Dave Hansen wrote: > On 12/10/21 7:43 AM, Brijesh Singh wrote: > > +static void sev_prep_identity_maps(void) > > +{ > > + /* > > + * The ConfidentialComputing blob is used very early in uncompressed > > + * kernel to find the in-memory cpuid table to handle cpuid > > + * instructions. Make sure an identity-mapping exists so it can be > > + * accessed after switchover. > > + */ > > + if (sev_snp_enabled()) { > > + struct cc_blob_sev_info *cc_info = > > + (void *)(unsigned long)boot_params->cc_blob_address; > > + > > + add_identity_map((unsigned long)cc_info, > > + (unsigned long)cc_info + sizeof(*cc_info)); > > + add_identity_map((unsigned long)cc_info->cpuid_phys, > > + (unsigned long)cc_info->cpuid_phys + cc_info->cpuid_len); > > + } > > The casting here is pretty ugly. Also, isn't ->cpuid_phys already a > u64? Whats the idea behind casting it? > > I also have a sneaking suspicion that a single "unsigned long cc_blob" > could remove virtually all the casting. Does this work? > > unsigned long cc_blob = boot_params->cc_blob_addres; > struct cc_blob_sev_info *cc_info; > > add_identity_map(cc_blob, cc_blob + sizeof(*cc_info)); > > cc_info = (struct cc_blob_sev_info *)cc_blob; > add_identity_map(cc_info->cpuid_phys, > cc_info->cpuid_phys + cc_info->cpuid_len); Yes, the cc->cpuid_phys cast is not needed, and your suggested implementation is clearer and compiles/runs without any issues. I'll implement it this way for the next spin. Thanks!