From: David Woodhouse <dwmw2@infradead.org>
To: Jim Mattson <jmattson@google.com>, Paolo Bonzini <pbonzini@redhat.com>
Cc: KarimAllah Ahmed <karahmed@amazon.com>,
KarimAllah Ahmed <karahmed@amazon.de>,
kvm list <kvm@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
the arch/x86 maintainers <x86@kernel.org>,
Asit Mallick <asit.k.mallick@intel.com>,
Arjan Van De Ven <arjan.van.de.ven@intel.com>,
Dave Hansen <dave.hansen@intel.com>,
Andi Kleen <ak@linux.intel.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Tim Chen <tim.c.chen@linux.intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Dan Williams <dan.j.williams@intel.com>,
Jun Nakajima <jun.nakajima@intel.com>,
Greg KH <gregkh@linuxfoundation.org>,
Andy Lutomirski <luto@kernel.org>,
Ashok Raj <ashok.raj@intel.com>
Subject: Re: [PATCH v5 4/5] KVM: VMX: Allow direct access to MSR_IA32_SPEC_CTRL
Date: Wed, 31 Jan 2018 21:59:41 +0000 [thread overview]
Message-ID: <1517435981.18619.215.camel@infradead.org> (raw)
In-Reply-To: <CALMp9eRF4_khB40b1_HmUj9K+FPE5X0M+KUkthi7k_rdQdgwoA@mail.gmail.com>
[-- Attachment #1: Type: text/plain, Size: 986 bytes --]
On Wed, 2018-01-31 at 13:53 -0800, Jim Mattson wrote:
> On Wed, Jan 31, 2018 at 1:42 PM, Paolo Bonzini <pbonzini@redhat.com> wrote:
>
> > Can we just say it sucks to be L2 too? :) Because in the end as long as
> > no one ever writes to spec_ctrl, everybody is happy.
>
> Unfortunately, quite a few OS vendors shipped IBRS-based mitigations
> earlier this month. (Has Redhat stopped writing to IA32_SPEC_CTRL yet?
> :-)
>
> And in the long run, everyone is going to set IA32_SPEC_CTRL.IBRS=1 on
> CPUs with IA32_ARCH_CAPABILITIES.IBRS_ALL.
I'm actually working on IBRS_ALL at the moment.
I was tempted to *not* let the guests turn it off. Expose SPEC_CTRL but
just make it a no-op.
Or if that really doesn't fly, perhaps with IBRS_ALL we should invert
the logic. Set IBRS to 1 on vCPU reset, and only if it's set to *zero*
do we pass through the MSR and set the save_spec_ctrl_on_exit flag.
But let's get the code for *current* hardware done first...
[-- Attachment #2: smime.p7s --]
[-- Type: application/x-pkcs7-signature, Size: 5213 bytes --]
next prev parent reply other threads:[~2018-01-31 21:59 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-31 19:37 [PATCH v5 0/5] KVM: Expose speculation control feature to guests KarimAllah Ahmed
2018-01-31 19:37 ` [PATCH v5 1/5] KVM: x86: Update the reverse_cpuid list to include CPUID_7_EDX KarimAllah Ahmed
2018-01-31 20:22 ` Konrad Rzeszutek Wilk
2018-01-31 19:37 ` [PATCH v5 2/5] KVM: x86: Add IBPB support KarimAllah Ahmed
2018-01-31 19:45 ` Jim Mattson
2018-01-31 19:53 ` David Woodhouse
2018-01-31 19:55 ` Jim Mattson
2018-02-01 0:27 ` KarimAllah Ahmed
2018-01-31 20:28 ` Konrad Rzeszutek Wilk
2018-01-31 20:36 ` KarimAllah Ahmed
2018-02-01 4:54 ` Tom Lendacky
2018-02-01 17:00 ` Raj, Ashok
2018-01-31 19:37 ` [PATCH v5 3/5] KVM: VMX: Emulate MSR_IA32_ARCH_CAPABILITIES KarimAllah Ahmed
2018-01-31 19:37 ` [PATCH v5 4/5] KVM: VMX: Allow direct access to MSR_IA32_SPEC_CTRL KarimAllah Ahmed
2018-01-31 19:53 ` Jim Mattson
2018-01-31 20:00 ` David Woodhouse
2018-01-31 20:01 ` KarimAllah Ahmed
2018-01-31 20:18 ` Jim Mattson
2018-01-31 20:21 ` David Woodhouse
2018-01-31 21:18 ` Jim Mattson
2018-01-31 22:05 ` David Woodhouse
2018-01-31 20:34 ` Paolo Bonzini
2018-01-31 20:54 ` Jim Mattson
2018-01-31 21:00 ` Paolo Bonzini
2018-01-31 21:05 ` Jim Mattson
2018-01-31 21:17 ` Woodhouse, David
2018-01-31 21:42 ` Paolo Bonzini
2018-01-31 21:53 ` Jim Mattson
2018-01-31 21:59 ` Paolo Bonzini
2018-01-31 21:59 ` David Woodhouse [this message]
2018-01-31 22:06 ` Jim Mattson
2018-01-31 22:10 ` David Woodhouse
2018-01-31 22:21 ` Linus Torvalds
2018-01-31 22:53 ` Andy Lutomirski
2018-02-01 14:09 ` Paolo Bonzini
2018-01-31 22:52 ` KarimAllah Ahmed
2018-02-01 0:24 ` KarimAllah Ahmed
2018-02-01 4:26 ` Konrad Rzeszutek Wilk
2018-02-01 13:25 ` David Woodhouse
2018-02-01 17:37 ` KarimAllah Ahmed
2018-02-01 17:46 ` KarimAllah Ahmed
2018-02-01 14:19 ` Konrad Rzeszutek Wilk
2018-02-01 14:28 ` KarimAllah Ahmed
2018-01-31 22:56 ` Raj, Ashok
2018-01-31 19:37 ` [PATCH v5 5/5] KVM: SVM: " KarimAllah Ahmed
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=1517435981.18619.215.camel@infradead.org \
--to=dwmw2@infradead.org \
--cc=aarcange@redhat.com \
--cc=ak@linux.intel.com \
--cc=arjan.van.de.ven@intel.com \
--cc=ashok.raj@intel.com \
--cc=asit.k.mallick@intel.com \
--cc=dan.j.williams@intel.com \
--cc=dave.hansen@intel.com \
--cc=gregkh@linuxfoundation.org \
--cc=jmattson@google.com \
--cc=jun.nakajima@intel.com \
--cc=karahmed@amazon.com \
--cc=karahmed@amazon.de \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@kernel.org \
--cc=pbonzini@redhat.com \
--cc=tglx@linutronix.de \
--cc=tim.c.chen@linux.intel.com \
--cc=torvalds@linux-foundation.org \
--cc=x86@kernel.org \
/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
all inboxes | Powered by JetHome®