linux-kernel - Re: [PATCH] KVM: X86: Allow userspace to define the microcode version

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: <7eeb63dd-5f7f-df91-47b1-7b15005cf45c@redhat.com>
Date:   Mon, 23 Apr 2018 18:03:40 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Eduardo Habkost <ehabkost@...hat.com>,
        Wanpeng Li <kernellwp@...il.com>,
        LKML <linux-kernel@...r.kernel.org>, kvm <kvm@...r.kernel.org>,
        Radim Krčmář <rkrcmar@...hat.com>
Subject: Re: [PATCH] KVM: X86: Allow userspace to define the microcode version

On 23/04/2018 14:58, Borislav Petkov wrote:
>>>> QEMU can't get the host value by rdmsr MSR_IA32_UCODE_REV directly
>>>> since rdmsr will #GP when ring !=0, any idea?
>>> By looking at kvm_get_msr_feature(), it looks like
>>> ioctl(system_fd, KVM_GET_MSRS) would return the host MSR value
>>> for us.
>> Yes, that's exactly what it was introduced for (together with other MSRs
>> including VMX capabilities).
> Can't qemu do:
> 
> grep microcode /proc/cpuinfo | awk '{ print $3 }' | head -n 1
> 
> ?

Yes, but you took that a statement bit too narrowly.

We didn't include KVM_GET_MSRS because microcode version wasn't
otherwise available; rather, there's a general need for KVM userspace to
know the values of host MSRs, and microcode is an example.

Paolo