Date: Sun, 29 Oct 2017 21:45:28 +0000 From: bugzilla-noreply@freebsd.org To: freebsd-virtualization@FreeBSD.org Subject: [Bug 218662] bhyve exposes CPU feature SDBG to guests, causing guest panic on OpenBSD 6.1 Message-ID: <bug-218662-27103-bBPYZOJblT@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-218662-27103@https.bugs.freebsd.org/bugzilla/> References: <bug-218662-27103@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D218662 Brandon Bergren <freebsd@bdragon.rtk0.net> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |freebsd@bdragon.rtk0.net --- Comment #2 from Brandon Bergren <freebsd@bdragon.rtk0.net> --- Created attachment 187571 --> https://bugs.freebsd.org/bugzilla/attachment.cgi?id=3D187571&action= =3Dedit VMM patch (from HardenedBSD) This affects me too. HardenedBSD has the most elegant fix at https://github.com/HardenedBSD/hardenedBSD/commit/e76fcb77ba82649bc6aed808a= f06d6d2184847d8 -- I have attached a copy of the patch. I can confirm that with just that p= atch I can successfully run OpenBSD 6.1 in bhyve on my machine that is otherwise affected by this problem. I believe it makes a lot more sense than emulating the MSR (i.e. what https://github.com/HardenedBSD/hardenedBSD/commit/cc91b57f4d1dabddfbf8b1e76= 55 does.) My SuperMicro C7Z170-OCE board actually has bios options for enabling and disabling the silicon debug status and lock bit, so if I were to misconfigu= re my bios, the countermeasure would have actually been effective (when applie= d to the host). I can verify though that with it disabled in the bios, it is indeed locked down, without needing the countermeasure. root@narwhal:~ # kldload cpuctl root@narwhal:~ # cpucontrol -m 0xc80 /dev/cpuctl0 MSR 0xc80: 0x00000000 0x40000000 I still think the countermeasure is a good idea though! https://github.com/HardenedBSD/hardenedBSD/commit/da28546280938e19e866d2e11= a9ccda3c4ca82fa is a version of the countermeasure that checks the virtualization flag too = so it will avoid tickling the bhyve limitation while still providing protectio= n. But at the very least, filter the SDBG feature flag. --=20 You are receiving this mail because: You are the assignee for the bug.=
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