From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To: Wanpeng Li <kernellwp@gmail.com>
Cc: "Paolo Bonzini" <pbonzini@redhat.com>,
"Eduardo Habkost" <ehabkost@redhat.com>,
"Borislav Petkov" <bp@alien8.de>,
LKML <linux-kernel@vger.kernel.org>, kvm <kvm@vger.kernel.org>,
"Radim Krčmář" <rkrcmar@redhat.com>
Subject: Re: [PATCH] KVM: X86: Allow userspace to define the microcode version
Date: Mon, 23 Apr 2018 23:14:00 -0400 [thread overview]
Message-ID: <20180424031400.GA22608@char.us.oracle.com> (raw)
In-Reply-To: <CANRm+CzxG5cm8ECopzGYpF3E3RTjvFGD3_7o8S=tffFxnvYoiA@mail.gmail.com>
On Tue, Apr 24, 2018 at 10:59:04AM +0800, Wanpeng Li wrote:
> 2018-04-18 18:36 GMT+08:00 Paolo Bonzini <pbonzini@redhat.com>:
> > On 18/04/2018 11:03, Eduardo Habkost wrote:
> >>>> QEMU setting ucode_rev automatically using the host value when
> >>>> using "-cpu host" (with no need for explicit ucode_rev option)
> >>>> makes sense to me.
> >>> 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).
>
> How about the live migration? What will happen if the source and
> destination machines have different microcode version?
You would need to include the microcode version in the migration stream.
But this brings another point - what if we want to manifest certain
new CPUID bits?
For example, see:
https://software.intel.com/sites/default/files/managed/1d/46/Retpoline-A-Branch-Target-Injection-Mitigation.pdf
5.3:
"To remedy this situation, an operating system running as a VM can query bit 2 of the
IA32_ARCH_CAPABILITIES MSR, known as “RSB Alternate” (RSBA). When RSBA is set, it
indicates that the VM may run on a processor vulnerable to exploits of Empty RSB
conditions regardless of the processor’s DisplayFamily/DisplayModel signature, and
that the operating system should deploy appropriate mitigations. Virtual machine
managers (VMM) may set RSBA via MSR interception to indicate that a virtual machine
might run at some time in the future on a vulnerable processor."
Perhaps the guest should do a bit of sampling of various CPUIDs as the migration
has been done? Is there a nice KVM hook inside of the guest to do this?
>
> Regards,
> Wanpeng Li
next prev parent reply other threads:[~2018-04-24 3:15 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-26 7:23 [PATCH] KVM: X86: Allow userspace to define the microcode version Wanpeng Li
2018-02-26 9:41 ` Borislav Petkov
2018-02-26 10:06 ` Wanpeng Li
2018-02-26 10:49 ` Borislav Petkov
2018-02-26 11:02 ` Wanpeng Li
2018-02-26 11:16 ` Borislav Petkov
2018-02-26 11:25 ` Wanpeng Li
2018-02-26 11:30 ` Borislav Petkov
2018-02-26 11:37 ` Wanpeng Li
2018-02-26 11:44 ` Borislav Petkov
2018-02-26 11:52 ` Wanpeng Li
2018-02-26 11:54 ` Paolo Bonzini
2018-02-26 12:15 ` Borislav Petkov
2018-02-26 12:16 ` Paolo Bonzini
2018-02-26 12:18 ` Paolo Bonzini
2018-02-26 12:22 ` Borislav Petkov
2018-02-26 12:41 ` Paolo Bonzini
2018-02-26 13:05 ` Borislav Petkov
2018-02-26 14:39 ` Konrad Rzeszutek Wilk
2018-02-26 14:46 ` Paolo Bonzini
2018-02-26 19:37 ` Borislav Petkov
2018-02-26 20:51 ` Konrad Rzeszutek Wilk
2018-02-26 21:30 ` Konrad Rzeszutek Wilk
2018-02-27 8:33 ` Paolo Bonzini
2018-03-08 9:24 ` [tip:x86/pti] x86/spectre_v2: Don't check microcode versions when running under hypervisors tip-bot for Konrad Rzeszutek Wilk
2018-04-17 10:40 ` [PATCH] KVM: X86: Allow userspace to define the microcode version Wanpeng Li
2018-04-17 20:24 ` Eduardo Habkost
2018-04-18 3:24 ` Wanpeng Li
2018-04-18 9:03 ` Eduardo Habkost
2018-04-18 10:36 ` Paolo Bonzini
2018-04-23 12:58 ` Borislav Petkov
2018-04-23 13:08 ` Eduardo Habkost
2018-04-23 13:23 ` Borislav Petkov
2018-04-23 16:03 ` Paolo Bonzini
2018-04-24 2:59 ` Wanpeng Li
2018-04-24 3:14 ` Konrad Rzeszutek Wilk [this message]
2018-04-24 5:09 ` Paolo Bonzini
2018-04-24 13:44 ` Konrad Rzeszutek Wilk
2018-04-24 2:56 ` Wanpeng Li
2018-02-26 11:47 ` Paolo Bonzini
2018-02-26 12:20 ` Borislav Petkov
2018-02-26 9:26 Liran Alon
2018-02-26 10:08 ` Wanpeng Li
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20180424031400.GA22608@char.us.oracle.com \
--to=konrad.wilk@oracle.com \
--cc=bp@alien8.de \
--cc=ehabkost@redhat.com \
--cc=kernellwp@gmail.com \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=pbonzini@redhat.com \
--cc=rkrcmar@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).