From: Borislav Petkov <bp@alien8.de>
To: Dmitry Vyukov <dvyukov@google.com>
Cc: George Kennedy <george.kennedy@oracle.com>,
Sean Christopherson <sean.j.christopherson@intel.com>,
Joerg Roedel <joro@8bytes.org>,
Paolo Bonzini <pbonzini@redhat.com>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
KVM list <kvm@vger.kernel.org>,
syzkaller <syzkaller@googlegroups.com>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>
Subject: Re: kernel BUG at arch/x86/kvm/x86.c:361! on AMD CPU
Date: Tue, 18 Jun 2019 20:27:33 +0200 [thread overview]
Message-ID: <20190618182733.GD26346@zn.tnic> (raw)
In-Reply-To: <CACT4Y+bnKwniAikESjDckaTW=vE1hu8yc4DuoSFwP3qTS4NpmA@mail.gmail.com>
On Tue, Jun 18, 2019 at 08:01:06PM +0200, Dmitry Vyukov wrote:
> I am not a KVM folk either, but FWIW syzkaller is capable of creating
> a double-nested VM.
Aaaha, there it is. :)
> The code is somewhat VMX-specific, but it should
> be capable at least executing some SVM instructions inside of guest.
> This code setups VM to run a given instruction sequences (should be generic):
> https://github.com/google/syzkaller/blob/34bf9440bd06034f86b5d9ac8afbf078129cbdae/executor/common_kvm_amd64.h
> The instruction generator is based on Intel XED so it may be somewhat
> Intel-biased, but at least I see some mentions of SVM there:
> https://raw.githubusercontent.com/google/syzkaller/34bf9440bd06034f86b5d9ac8afbf078129cbdae/pkg/ifuzz/gen/all-enc-instructions.txt
Right, and that right there looks wrong:
ICLASS : VMLOAD
CPL : 3
CATEGORY : SYSTEM
EXTENSION : SVM
ATTRIBUTES: PROTECTED_MODE
PATTERN : 0x0F 0x01 MOD[0b11] MOD=3 REG[0b011] RM[0b010]
OPERANDS : REG0=OrAX():r:IMPL
That is, *if* "CPL: 3" above means in XED context that VMLOAD is
supposed to be run in CPL3, then this is wrong because VMLOAD #GPs if
CPL was not 0. Ditto for VMRUN and a couple of others.
Perhaps that support was added at some point but not really run on AMD
hw yet...
--
Regards/Gruss,
Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
next prev parent reply other threads:[~2019-06-18 18:27 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <37952f51-7687-672c-45d9-92ba418c9133@oracle.com>
2019-06-12 16:12 ` kernel BUG at arch/x86/kvm/x86.c:361! on AMD CPU Borislav Petkov
[not found] ` <af0054d1-1fc8-c106-b503-ca91da5a6fee@oracle.com>
2019-06-12 19:51 ` Borislav Petkov
2019-06-12 20:54 ` Sean Christopherson
2019-06-13 7:18 ` Borislav Petkov
[not found] ` <df80299b-8e1f-f48b-a26b-c163b4018d01@oracle.com>
2019-06-18 17:51 ` Borislav Petkov
2019-06-18 18:01 ` Dmitry Vyukov
2019-06-18 18:27 ` Borislav Petkov [this message]
2019-06-18 19:17 ` Paolo Bonzini
2019-06-18 19:34 ` George Kennedy
2019-06-23 13:15 ` Dmitry Vyukov
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