From 17d214c2ca9f110db3fa2a10d6b448d624e87774 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Corvin=20K=C3=B6hne?= Date: Thu, 15 Apr 2021 13:49:19 +1000 Subject: [PATCH] bhyve: implement rdmsr for MSR_IA32_FEATURE_CONTROL Without the -w option, Windows guests crash on boot. This is caused by a rdmsr of MSR_IA32_FEATURE_CONTROL. Windows checks this MSR to determine enabled VMX features. This MSR isn't emulated in bhyve, so a #GP exception is injected which causes Windows to crash. Fix by returning a rdmsr of MSR_IA32_FEATURE_CONTROL with Lock Bit set and VMX disabled to informWindows that VMX isn't available. Reviewed by: jhb, grehan (bhyve) MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D29665 --- usr.sbin/bhyve/xmsr.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/usr.sbin/bhyve/xmsr.c b/usr.sbin/bhyve/xmsr.c index 0b87821836b7..1a7f98ee222a 100644 --- a/usr.sbin/bhyve/xmsr.c +++ b/usr.sbin/bhyve/xmsr.c @@ -124,6 +124,14 @@ emulate_rdmsr(struct vmctx *ctx, int vcpu, uint32_t num, uint64_t *val) */ *val = 0x000a1003; break; + case MSR_IA32_FEATURE_CONTROL: + /* + * Windows guests check this MSR. + * Set the lock bit to avoid writes + * to this MSR. + */ + *val = IA32_FEATURE_CONTROL_LOCK; + break; default: error = -1; break;