[src/trunk]: src/sys/dev/nvmm/x86 nvmm-x86-svm: improve the handling of MSR_EFER

[maxv <maxv%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/128e1ee03d56
branches:  trunk
changeset: 943100:128e1ee03d56
user:      maxv <maxv%NetBSD.org@localhost>
date:      Wed Aug 26 16:33:03 2020 +0000

description:
nvmm-x86-svm: improve the handling of MSR_EFER

Intercept reads of it as well, just to mask EFER_SVME, which the guest
doesn't need to see.

diffstat:

 sys/dev/nvmm/x86/nvmm_x86_svm.c |  11 ++++++++---
 1 files changed, 8 insertions(+), 3 deletions(-)

diffs (39 lines):

diff -r 881ca2ceaa35 -r 128e1ee03d56 sys/dev/nvmm/x86/nvmm_x86_svm.c
--- a/sys/dev/nvmm/x86/nvmm_x86_svm.c   Wed Aug 26 16:32:02 2020 +0000
+++ b/sys/dev/nvmm/x86/nvmm_x86_svm.c   Wed Aug 26 16:33:03 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: nvmm_x86_svm.c,v 1.73 2020/08/26 16:32:02 maxv Exp $   */
+/*     $NetBSD: nvmm_x86_svm.c,v 1.74 2020/08/26 16:33:03 maxv Exp $   */
 
 /*
  * Copyright (c) 2018-2020 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: nvmm_x86_svm.c,v 1.73 2020/08/26 16:32:02 maxv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: nvmm_x86_svm.c,v 1.74 2020/08/26 16:33:03 maxv Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -1170,6 +1170,12 @@
        size_t i;
 
        if (exit->reason == NVMM_VCPU_EXIT_RDMSR) {
+               if (exit->u.rdmsr.msr == MSR_EFER) {
+                       val = vmcb->state.efer & ~EFER_SVME;
+                       vmcb->state.rax = (val & 0xFFFFFFFF);
+                       cpudata->gprs[NVMM_X64_GPR_RDX] = (val >> 32);
+                       goto handled;
+               }
                if (exit->u.rdmsr.msr == MSR_NB_CFG) {
                        val = NB_CFG_INITAPICCPUIDLO;
                        vmcb->state.rax = (val & 0xFFFFFFFF);
@@ -2195,7 +2201,6 @@
 
        /* Allow direct access to certain MSRs. */
        memset(cpudata->msrbm, 0xFF, MSRBM_SIZE);
-       svm_vcpu_msr_allow(cpudata->msrbm, MSR_EFER, true, false);
        svm_vcpu_msr_allow(cpudata->msrbm, MSR_STAR, true, true);
        svm_vcpu_msr_allow(cpudata->msrbm, MSR_LSTAR, true, true);
        svm_vcpu_msr_allow(cpudata->msrbm, MSR_CSTAR, true, true);