x86/sev: Don't hang but terminate on failure to remap SVSM CA

Commit

  09d35045cd0f  ("x86/sev: Avoid WARN()s and panic()s in early boot code")

replaced a panic() that could potentially hit before the kernel is even
mapped with a deadloop, to ensure that execution does not proceed when the
condition in question hits.

As Tom suggests, it is better to terminate and return to the hypervisor
in this case, using a newly invented failure code to describe the
failure condition.

Suggested-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Link: https://lore.kernel.org/all/9ce88603-20ca-e644-2d8a-aeeaf79cde69@amd.com

diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c
index 499b41953e3cd429e3943d801ab1ed57d3085b79..86898547056e71e388edf525b03997cdd4584808 100644 (file)
--- a/arch/x86/coco/sev/core.c
+++ b/arch/x86/coco/sev/core.c
@@ -2356,8 +2356,8 @@ static __head void svsm_setup(struct cc_blob_sev_info *cc_info)
        call.rax = SVSM_CORE_CALL(SVSM_CORE_REMAP_CA);
        call.rcx = pa;
        ret = svsm_perform_call_protocol(&call);
-       while (ret)
-               cpu_relax(); /* too early to panic */
+       if (ret)
+               sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_SVSM_CA_REMAP_FAIL);
 
        RIP_REL_REF(boot_svsm_caa) = (struct svsm_ca *)pa;
        RIP_REL_REF(boot_svsm_caa_pa) = pa;

diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h
index 50f5666938c09768772e34c44758548f6fbe5184..577b64dda8b4edf87389543f22bea8163ef41847 100644 (file)
--- a/arch/x86/include/asm/sev-common.h
+++ b/arch/x86/include/asm/sev-common.h
@@ -206,6 +206,7 @@ struct snp_psc_desc {
 #define GHCB_TERM_NO_SVSM              7       /* SVSM is not advertised in the secrets page */
 #define GHCB_TERM_SVSM_VMPL0           8       /* SVSM is present but has set VMPL to 0 */
 #define GHCB_TERM_SVSM_CAA             9       /* SVSM is present but CAA is not page aligned */
+#define GHCB_TERM_SVSM_CA_REMAP_FAIL   10      /* SVSM is present but CA could not be remapped */
 
 #define GHCB_RESP_CODE(v)              ((v) & GHCB_MSR_INFO_MASK)