linux-kernel - Re: [PATCH v6 21/22] x86/boot: Move startup code out of _

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Message-ID: <20250811190306.GAaJo-ai4M2aVod6_V@fat_crate.local>
Date: Mon, 11 Aug 2025 21:03:06 +0200
From: Borislav Petkov <bp@...en8.de>
To: Tom Lendacky <thomas.lendacky@....com>
Cc: Ard Biesheuvel <ardb+git@...gle.com>, linux-kernel@...r.kernel.org,
	linux-efi@...r.kernel.org, x86@...nel.org,
	Ard Biesheuvel <ardb@...nel.org>, Ingo Molnar <mingo@...nel.org>,
	Kevin Loughlin <kevinloughlin@...gle.com>,
	Josh Poimboeuf <jpoimboe@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Nikunj A Dadhania <nikunj@....com>,
	Neeraj Upadhyay <Neeraj.Upadhyay@....com>
Subject: Re: [PATCH v6 21/22] x86/boot: Move startup code out of __head
 section

On Mon, Aug 11, 2025 at 01:05:42PM -0500, Tom Lendacky wrote:
> Yes, that works. Or just get rid of snp_abort() and call
> sev_es_terminate() directly. Secure AVIC could even use an
> SEV_TERM_SET_LINUX specific code instead of the generic failure code.

I *love* deleting code. Here's something to start the debate:

---
diff --git a/arch/x86/boot/startup/sev-startup.c b/arch/x86/boot/startup/sev-startup.c
index 7a8128dc076e..19b23e6d2dbe 100644
--- a/arch/x86/boot/startup/sev-startup.c
+++ b/arch/x86/boot/startup/sev-startup.c
@@ -135,7 +135,7 @@ static struct cc_blob_sev_info *__init find_cc_blob(struct boot_params *bp)
 
 found_cc_info:
 	if (cc_info->magic != CC_BLOB_SEV_HDR_MAGIC)
-		snp_abort();
+		sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SNP_UNSUPPORTED);
 
 	return cc_info;
 }
@@ -209,8 +209,3 @@ bool __init snp_init(struct boot_params *bp)
 
 	return true;
 }
-
-void __init __noreturn snp_abort(void)
-{
-	sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SNP_UNSUPPORTED);
-}
diff --git a/arch/x86/boot/startup/sme.c b/arch/x86/boot/startup/sme.c
index 39e7e9d18974..e389b39fa2a9 100644
--- a/arch/x86/boot/startup/sme.c
+++ b/arch/x86/boot/startup/sme.c
@@ -531,7 +531,7 @@ void __init sme_enable(struct boot_params *bp)
 	 * enablement abort the guest.
 	 */
 	if (snp_en ^ !!(msr & MSR_AMD64_SEV_SNP_ENABLED))
-		snp_abort();
+		sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SNP_UNSUPPORTED);
 
 	/* Check if memory encryption is enabled */
 	if (feature_mask == AMD_SME_BIT) {
diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h
index 0020d77a0800..01a6e4dbe423 100644
--- a/arch/x86/include/asm/sev-common.h
+++ b/arch/x86/include/asm/sev-common.h
@@ -208,6 +208,7 @@ struct snp_psc_desc {
 #define GHCB_TERM_SVSM_CAA		9	/* SVSM is present but CAA is not page aligned */
 #define GHCB_TERM_SECURE_TSC		10	/* Secure TSC initialization failed */
 #define GHCB_TERM_SVSM_CA_REMAP_FAIL	11	/* SVSM is present but CA could not be remapped */
+#define GHCB_TERM_SAVIC_FAIL		12	/* Secure AVIC-specific failure */
 
 #define GHCB_RESP_CODE(v)		((v) & GHCB_MSR_INFO_MASK)
 
diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
index 2b8a779f1477..e907646b4e4b 100644
--- a/arch/x86/include/asm/sev.h
+++ b/arch/x86/include/asm/sev.h
@@ -512,7 +512,6 @@ void snp_set_memory_shared(unsigned long vaddr, unsigned long npages);
 void snp_set_memory_private(unsigned long vaddr, unsigned long npages);
 void snp_set_wakeup_secondary_cpu(void);
 bool snp_init(struct boot_params *bp);
-void __noreturn snp_abort(void);
 void snp_dmi_setup(void);
 int snp_issue_svsm_attest_req(u64 call_id, struct svsm_call *call, struct svsm_attest_call *input);
 void snp_accept_memory(phys_addr_t start, phys_addr_t end);
@@ -590,7 +589,6 @@ static inline void snp_set_memory_shared(unsigned long vaddr, unsigned long npag
 static inline void snp_set_memory_private(unsigned long vaddr, unsigned long npages) { }
 static inline void snp_set_wakeup_secondary_cpu(void) { }
 static inline bool snp_init(struct boot_params *bp) { return false; }
-static inline void snp_abort(void) { }
 static inline void snp_dmi_setup(void) { }
 static inline int snp_issue_svsm_attest_req(u64 call_id, struct svsm_call *call, struct svsm_attest_call *input)
 {
diff --git a/arch/x86/kernel/apic/x2apic_savic.c b/arch/x86/kernel/apic/x2apic_savic.c
index bea844f28192..f0270ce16e6c 100644
--- a/arch/x86/kernel/apic/x2apic_savic.c
+++ b/arch/x86/kernel/apic/x2apic_savic.c
@@ -26,7 +26,7 @@ static int savic_probe(void)
 
 	if (!x2apic_mode) {
 		pr_err("Secure AVIC enabled in non x2APIC mode\n");
-		snp_abort();
+		sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_SAVIC_FAIL);
 		/* unreachable */
 	}
 
diff --git a/tools/objtool/noreturns.h b/tools/objtool/noreturns.h
index 6a922d046b8e..802895fae3ca 100644
--- a/tools/objtool/noreturns.h
+++ b/tools/objtool/noreturns.h
@@ -45,7 +45,6 @@ NORETURN(rewind_stack_and_make_dead)
 NORETURN(rust_begin_unwind)
 NORETURN(rust_helper_BUG)
 NORETURN(sev_es_terminate)
-NORETURN(snp_abort)
 NORETURN(start_kernel)
 NORETURN(stop_this_cpu)
 NORETURN(usercopy_abort)

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette