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

Commit 09d3504 ("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 <[email protected]> Signed-off-by: Ard Biesheuvel <[email protected]> Signed-off-by: Borislav Petkov (AMD) <[email protected]> Reviewed-by: Tom Lendacky <[email protected]> Link: https://lore.kernel.org/all/[email protected]
torvalds · Jan 7, 2025 · 8939301 · 8939301
1 parent 99b863d
commit 8939301
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Showing 2 changed files with 3 additions and 2 deletions.
diff --git 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
@@ -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)