From: mlarkin <mlarkin@openbsd.org>
Date: Wed, 26 Apr 2023 15:40:51 +0000 (+0000)
Subject: Incorporate r1.140 and r1.141 of vmm.c:
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=c68291b4a3d0bcfb48a836752563ffa0637a9625;p=openbsd

Incorporate r1.140 and r1.141 of vmm.c:

----------------------------
revision 1.341
date: 2023/04/26 09:39:56;  author: dv;  state: Exp;  lines: +3 -3;  commitid: 1XztmVbxa8OP2xYi;
Unbreak vmm on Intel. Mistakenly enabled CET on non-CET systems.

Found by anton@ & jsg@
----------------------------
revision 1.340
date: 2023/04/24 16:53:57;  author: dv;  state: Exp;  lines: +11 -1;  commitid: q9qQ55f7h2gen8N4;
vmm(4): allow guests to enable and use supervisor IBT.

Why should hosts have all the fun? Conditionally unmask the cpuid
bits for IBT and allow r/w access to the supervisor CET msr.

Will need revisiting when we introduce usage of userland CET msr.
---

diff --git a/sys/arch/amd64/amd64/vmm_machdep.c b/sys/arch/amd64/amd64/vmm_machdep.c
index acfca6d2947..dc30e35a8be 100644
--- a/sys/arch/amd64/amd64/vmm_machdep.c
+++ b/sys/arch/amd64/amd64/vmm_machdep.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: vmm_machdep.c,v 1.2 2023/04/26 15:34:31 mlarkin Exp $ */
+/* $OpenBSD: vmm_machdep.c,v 1.3 2023/04/26 15:40:51 mlarkin Exp $ */
 /*
  * Copyright (c) 2014 Mike Larkin <mlarkin@openbsd.org>
  *
@@ -2859,6 +2859,10 @@ vcpu_reset_regs_vmx(struct vcpu *vcpu, struct vcpu_reg_state *vrs)
 	vmx_setmsrbr(vcpu, MSR_MISC_ENABLE);
 	vmx_setmsrbr(vcpu, MSR_TSC);
 
+	/* If host supports CET, pass through access to the guest. */
+	if (rcr4() & CR4_CET)
+		vmx_setmsrbrw(vcpu, MSR_S_CET);
+
 	/* XXX CR0 shadow */
 	/* XXX CR4 shadow */
 
@@ -6166,6 +6170,13 @@ vmm_handle_cpuid(struct vcpu *vcpu)
 				*rcx |= SEFF0ECX_PKU;
 			else
 				*rcx &= ~SEFF0ECX_PKU;
+
+			/* Expose IBT bit if we've enabled CET on the host. */
+			if (rcr4() & CR4_CET)
+				*rdx |= SEFF0EDX_IBT;
+			else
+				*rdx &= ~SEFF0EDX_IBT;
+
 		} else {
 			/* Unsupported subleaf */
 			DPRINTF("%s: function 0x07 (SEFF) unsupported subleaf "