Hi,

when booting an SEV enabled kernel on QEMU we noticed, that QEMU does not
annouce SME, only SEV.  I think this is reasonable, as SME is an orthogonal
mechanism to SEV.  Therefore do not depend on SME when checking for SEV.

From Sebastian Sturm <ssturm@genua.de>

Take care,
HJ.
-----------------------------------------------------------------------
commit 0495938dc80a047cace3cd282593256dbe51022d
Author: Hans-Joerg Hoexer <hshoexer@genua.de>
Date:   Thu Sep 12 13:08:17 2024 +0200

    kern: Enable booting with SEV on QEMU
    
    QEMU does not forward the SME feature if SEV is enabled. This removes
    the requirement for SME in the x64 boot code.
    
    From Sebastian Sturm <ssturm@genua.de>.

diff --git a/sys/arch/amd64/amd64/locore0.S b/sys/arch/amd64/amd64/locore0.S
index bc45eee7a09..ff9548c8b5d 100644
--- a/sys/arch/amd64/amd64/locore0.S
+++ b/sys/arch/amd64/amd64/locore0.S
@@ -273,33 +273,29 @@ cont:
 	 */
 	movl	$RELOC(cpu_vendor),%ebp
 	cmpl $0x68747541, (%ebp)	/* "Auth" */
-	jne	.Lno_smesev
+	jne	.Lno_sev
 	cmpl $0x69746e65, 4(%ebp)	/* "enti" */
-	jne	.Lno_smesev
+	jne	.Lno_sev
 	cmpl $0x444d4163, 8(%ebp)	/* "cAMD" */
-	jne	.Lno_smesev
+	jne	.Lno_sev
 
 	/* AMD CPU, check for SME and SEV. */
 	movl	$0x8000001f, %eax
 	cpuid
-	pushl	%eax
-	andl	$CPUIDEAX_SME, %eax	/* SME */
-	popl	%eax
-	jz	.Lno_smesev
 	andl	$CPUIDEAX_SEV, %eax	/* SEV */
-	jz	.Lno_smesev
+	jz	.Lno_sev
 
 	/* Are we in guest mode with SEV enabled? */
 	movl	$MSR_SEV_STATUS, %ecx
 	rdmsr
 	andl	$SEV_STAT_ENABLED, %eax
-	jz	.Lno_smesev
+	jz	.Lno_sev
 
 	/* Determine C bit position */
 	movl	%ebx, %ecx	/* %ebx from previous cpuid */
 	andl	$0x3f, %ecx
 	cmpl	$0x20, %ecx	/* must be at least bit 32 (counting from 0) */
-	jl	.Lno_smesev
+	jl	.Lno_sev
 	xorl	%eax, %eax
 	movl	%eax, RELOC(pg_crypt)
 	subl	$0x20, %ecx
@@ -338,7 +334,7 @@ cont:
 
 	movl	$0x1, RELOC(cpu_sev_guestmode)	/* we are a SEV guest */
 
-.Lno_smesev:
+.Lno_sev:
 
 	/*
 	 * Finished with old stack; load new %esp now instead of later so we

• smime.p7s (5K)