x86/sev: Don't use cc_platform_has() for early SEV-SNP calls
When running identity-mapped and depending on the kernel configuration, it is possible that the compiler uses jump tables when generating code for cc_platform_has(). 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. Similar to sme_encrypt_kernel(), use an open-coded direct check for the status of SNP rather than trying to eliminate the jump table. This preserves any code optimization in cc_platform_has() that can be useful post boot. It also limits the changes to SEV-specific files so that future compiler features won't necessarily require possible build changes just because they are not compatible with running identity-mapped. [ bp: Massage commit message. ] Fixes: 5e5ccff6 ("x86/sev: Add helper for validating pages in early enc attribute changes") Reported-by:Sean Christopherson <seanjc@google.com> Suggested-by:
Sean Christopherson <seanjc@google.com> Signed-off-by:
Tom Lendacky <thomas.lendacky@amd.com> Signed-off-by:
Borislav Petkov <bp@suse.de> Cc: <stable@vger.kernel.org> # 5.19.x Link: https://lore.kernel.org/all/YqfabnTRxFSM+LoX@google.com/
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