Re: [PATCH v11 39/45] x86/sev: Use firmware-validated CPUID for SEV-SNP guests

[Michael Roth <michael.roth@amd.com>]

On Thu, Mar 03, 2022 at 12:51:20PM +0100, Borislav Petkov wrote:
> On Thu, Feb 24, 2022 at 10:56:19AM -0600, Brijesh Singh wrote:
> > Also add an "sev_debug" kernel command-line parameter that will be used
> > (initially) to dump the CPUID table for debugging/analysis.
> 
> No, not "sev_debug" - "sev=debug".
> 
> I'm pretty sure there will be need for other SEV-specific cmdline
> options so this thing should be a set, i.e.,
> 	"sev=(option1,option2?,option3?,...)"
> 
> etc.
> 
> See mcheck_enable() and the comment above it for an example.

If I do it the mce_check() way it ends up looking something like the
below, is that what you add in mind?

In that case it seems to expect "mce=option1 mce=option2" etc. I could
open-code a parser to handle multiple options like sev=option1,option2
etc., but wanted to check with you first.

Also, should I go ahead and introduce struct sev_options now, or
just use a regular bool until more options are added later?

Thanks!

struct sev_options {
       bool debug;
};

static struct sev_options sev_cmdline_opts;

...

static int __init process_sev_options(char *str)
{
       if ((*str) == '=')
               str++;

       if (!strcmp(str, "debug")) {
               sev_cmdline_opts.debug = true;
       } else {
               pr_info("SEV command-line option '%s' was not ecognized\n", str);
               return 1;
       }

       return 0;
}
__setup("sev", process_sev_options);

static int __init report_cpuid_table(void)
{
    ...
    if (sev_cmdline_opts.debug)
        dump_cpuid_table();
}
arch_initcall(report_cpuid_table)

> 
> -- 
> Regards/Gruss,
>     Boris.
> 
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