| Subject | Re: [PATCH v8 33/40] x86/compressed/64: add identity mapping for Confidential Computing blob | From | Dave Hansen <> | Date | Fri, 10 Dec 2021 11:52:28 -0800 |
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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);
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