linux-kernel - Re: [GIT PULL] KVM changes for Linux 5.6-rc4

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <87zhcyfvmk.fsf@vitty.brq.redhat.com>
Date:   Mon, 02 Mar 2020 19:40:35 +0100
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        Oliver Upton <oupton@...gle.com>
Subject: Re: [GIT PULL] KVM changes for Linux 5.6-rc4

Paolo Bonzini <pbonzini@...hat.com> writes:

>       KVM: nVMX: Don't emulate instructions in guest mode

I just discovered that this patch breaks Hyper-V on KVM completely;
Oliver's 86f7e90ce8 ("KVM: VMX: check descriptor table exits on
instruction emulation") doesn't fix it either. The breakage manifests
itself as

 qemu-system-x86-23579 [005] 22018.775584: kvm_exit:             reason EPT_VIOLATION rip 0xfffff802987d6169 info 181 0
 qemu-system-x86-23579 [005] 22018.775584: kvm_nested_vmexit:    rip fffff802987d6169 reason EPT_VIOLATION info1 181 info2 0 int_info 0 int_info_err 0
 qemu-system-x86-23579 [005] 22018.775585: kvm_page_fault:       address febd0000 error_code 181
 qemu-system-x86-23579 [005] 22018.775592: kvm_emulate_insn:     0:fffff802987d6169: f3 a5
 qemu-system-x86-23579 [005] 22018.775593: kvm_emulate_insn:     0:fffff802987d6169: f3 a5 FAIL
 qemu-system-x86-23579 [005] 22018.775596: kvm_inj_exception:    #UD (0x0)

We probably need to re-enable instruction emulation for something...

-- 
Vitaly