Re: [PATCH] x86/sev: Don't use cc_platform_has() for early SEV-SNP calls

[Dave Hansen]

On 8/23/22 14:55, Tom Lendacky wrote:
> When running identity mapped and depending on the kernel configuration,
> it is possible that cc_platform_has() can have compiler generated code
> that uses jump tables. This causes a boot failure because the jump table
> uses un-mapped kernel virtual addresses, not identity mapped addresses.
> This has been seen with CONFIG_RETPOLINE=n.

So, we don't have *ANY* control over where the compiler uses jump
tables.  The kernel just happened to add some code that uses them, fell
over, and this adds a hack to get booting again.

Isn't this a bigger problem?