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.
