Commit 89393014 authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Borislav Petkov (AMD)
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x86/sev: Don't hang but terminate on failure to remap SVSM CA 



Commit

  09d35045  ("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: default avatarTom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: default avatarTom Lendacky <thomas.lendacky@amd.com>
Link: https://lore.kernel.org/all/9ce88603-20ca-e644-2d8a-aeeaf79cde69@amd.com
parent 99b863d2

arch/x86/coco/sev/core.c

+2 −2
Original line number Diff line number Diff line
@@ -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;

arch/x86/include/asm/sev-common.h

+1 −0
Original line number Diff line number Diff line
@@ -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)