Re: [PATCH v8 01/40] x86/compressed/64: detect/setup SEV/SME features earlier in boot

Dave Hansen
2021-12-10T19:23:28Z

On 12/10/21 11:12 AM, Borislav Petkov wrote:
> On Fri, Dec 10, 2021 at 09:42:53AM -0600, Brijesh Singh wrote:
>> @@ -447,6 +446,23 @@ SYM_CODE_START(startup_64)
>> call load_stage1_idt
>> popq %rsi
>>
>> +#ifdef CONFIG_AMD_MEM_ENCRYPT
>
> I guess that ifdeffery is not needed.

I think sev_enable() is only defined in arch/x86/boot/compressed/sev.c,
which is compiled via:

vmlinux-objs-$(CONFIG_AMD_MEM_ENCRYPT) += $(obj)/sev.o

So I think we either need the #ifdef or a stub for sev_enable()
somewhere else.

>> + /*
>> + * Now that the stage1 interrupt handlers are set up, #VC exceptions from
>> + * CPUID instructions can be properly handled for SEV-ES guests.
>> + *
>> + * For SEV-SNP, the CPUID table also needs to be set up in advance of any
>> + * CPUID instructions being issued, so go ahead and do that now via
>> + * sev_enable(), which will also handle the rest of the SEV-related
>> + * detection/setup to ensure that has been done in advance of any dependent
>> + * code.
>> + */
>> + pushq %rsi
>> + movq %rsi, %rdi /* real mode address */
>> + call sev_enable
>> + popq %rsi
>> +#endif