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

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  09d35045cd  ("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
This commit is contained in:
Ard Biesheuvel 2025-01-06 16:57:46 +01:00 committed by Borislav Petkov (AMD)
parent 99b863d2e8
commit 8939301434
2 changed files with 3 additions and 2 deletions
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4
arch/x86/coco/sev/core.c
View File

@ -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;

1
arch/x86/include/asm/sev-common.h
View File

@ -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)