untrusted comment: verify with openbsd-73-base.pub
RWQS90bYzZ4XFl/L1sXKI9Jm30jpG5J+42sawcM1OsKQO0A6b+LLS4wOuol4oxTLff7S4it3U8xs8bA7AMSuiCYOHA5N5LgmRwA=

OpenBSD 7.3 errata 022, December 10, 2023:

vmm(4) restored stale GDTR & TR values on vm exit which could lead to
memory corruption or kernel deadlocks.

Apply by doing:
    signify -Vep /etc/signify/openbsd-73-base.pub -x 022_vmm.patch.sig \
        -m - | (cd /usr/src && patch -p0)

And then rebuild and install a new kernel:
    KK=`sysctl -n kern.osversion | cut -d# -f1`
    cd /usr/src/sys/arch/`machine`/compile/$KK
    make obj
    make config
    make
    make install

Index: sys/arch/amd64/amd64/vmm.c
===================================================================
RCS file: /cvs/src/sys/arch/amd64/amd64/Attic/vmm.c,v
diff -u -p -r1.337 vmm.c
--- sys/arch/amd64/amd64/vmm.c	30 Jan 2023 14:05:36 -0000	1.337
+++ sys/arch/amd64/amd64/vmm.c	27 Nov 2023 16:39:06 -0000
@@ -4821,7 +4821,7 @@ vcpu_run_vmx(struct vcpu *vcpu, struct v
 {
 	int ret = 0, exitinfo;
 	struct region_descriptor gdt;
-	struct cpu_info *ci = curcpu();
+	struct cpu_info *ci = NULL;
 	uint64_t exit_reason, cr3, insn_error;
 	struct schedstate_percpu *spc;
 	struct vmx_invvpid_descriptor vid;
@@ -4900,26 +4900,6 @@ vcpu_run_vmx(struct vcpu *vcpu, struct v
 		memset(&vcpu->vc_exit, 0, sizeof(vcpu->vc_exit));
 	}
 
-	setregion(&gdt, ci->ci_gdt, GDT_SIZE - 1);
-	if (gdt.rd_base == 0) {
-		printf("%s: setregion\n", __func__);
-		return (EINVAL);
-	}
-
-	/* Host GDTR base */
-	if (vmwrite(VMCS_HOST_IA32_GDTR_BASE, gdt.rd_base)) {
-		printf("%s: vmwrite(0x%04X, 0x%llx)\n", __func__,
-		    VMCS_HOST_IA32_GDTR_BASE, gdt.rd_base);
-		return (EINVAL);
-	}
-
-	/* Host TR base */
-	if (vmwrite(VMCS_HOST_IA32_TR_BASE, (uint64_t)ci->ci_tss)) {
-		printf("%s: vmwrite(0x%04X, 0x%llx)\n", __func__,
-		    VMCS_HOST_IA32_TR_BASE, (uint64_t)ci->ci_tss);
-		return (EINVAL);
-	}
-
 	/* Host CR3 */
 	cr3 = rcr3();
 	if (vmwrite(VMCS_HOST_IA32_CR3, cr3)) {
@@ -4976,6 +4956,34 @@ vcpu_run_vmx(struct vcpu *vcpu, struct v
 #endif /* VMM_DEBUG */
 
 		vmm_update_pvclock(vcpu);
+
+		if (ci != curcpu()) {
+			ci = curcpu();
+			vcpu->vc_last_pcpu = ci;
+
+			setregion(&gdt, ci->ci_gdt, GDT_SIZE - 1);
+			if (gdt.rd_base == 0) {
+				printf("%s: setregion\n", __func__);
+				return (EINVAL);
+			}
+
+			/* Host GDTR base */
+			if (vmwrite(VMCS_HOST_IA32_GDTR_BASE, gdt.rd_base)) {
+				printf("%s: vmwrite(0x%04X, 0x%llx)\n",
+				    __func__, VMCS_HOST_IA32_GDTR_BASE,
+				    gdt.rd_base);
+				return (EINVAL);
+			}
+
+			/* Host TR base */
+			if (vmwrite(VMCS_HOST_IA32_TR_BASE,
+			    (uint64_t)ci->ci_tss)) {
+				printf("%s: vmwrite(0x%04X, 0x%llx)\n",
+				    __func__, VMCS_HOST_IA32_TR_BASE,
+				    (uint64_t)ci->ci_tss);
+				return (EINVAL);
+			}
+		}
 
 		/* Inject event if present */
 		if (vcpu->vc_event != 0) {