linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Paolo Bonzini <pbonzini@redhat.com>
To: Eduardo Habkost <ehabkost@redhat.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
	jmattson@google.com,
	Sean Christopherson <sean.j.christopherson@intel.com>
Subject: Re: [PATCH 5/5] KVM: vmx: use MSR_IA32_TSX_CTRL to hard-disable TSX on guest that lack it
Date: Thu, 21 Nov 2019 10:05:04 +0100	[thread overview]
Message-ID: <4a820b71-79eb-7d71-9cd2-93954cefcdd2@redhat.com> (raw)
In-Reply-To: <20191121022252.GX3812@habkost.net>

On 21/11/19 03:22, Eduardo Habkost wrote:
> On Mon, Nov 18, 2019 at 07:17:47PM +0100, Paolo Bonzini wrote:
>> If X86_FEATURE_RTM is disabled, the guest should not be able to access
>> MSR_IA32_TSX_CTRL.  We can therefore use it in KVM to force all
>> transactions from the guest to abort.
>>
>> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> 
> So, without this patch guest OSes will incorrectly report "Not
> affected" at /sys/devices/system/cpu/vulnerabilities/tsx_async_abort
> if RTM is disabled in the VM configuration.
> 
> Is there anything host userspace can do to detect this situation
> and issue a warning on that case?
> 
> Is there anything the guest kernel can do to detect this and not
> report a false negative at /sys/.../tsx_async_abort?

Unfortunately not.  The hypervisor needs to know about TAA in order to
mitigate it on behalf of the guest.  At least this doesn't require an
updated userspace and VM configuration!

Paolo


      reply	other threads:[~2019-11-21  9:05 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-18 18:17 [PATCH 0/5] KVM: vmx: implement MSR_IA32_TSX_CTRL for guests Paolo Bonzini
2019-11-18 18:17 ` [PATCH 1/5] KVM: x86: fix presentation of TSX feature in ARCH_CAPABILITIES Paolo Bonzini
2019-11-18 19:39   ` Jim Mattson
2019-11-18 20:48   ` Jim Mattson
2019-11-22 20:15   ` Sean Christopherson
2019-11-18 18:17 ` [PATCH 2/5] KVM: x86: do not modify masked bits of shared MSRs Paolo Bonzini
2019-11-19 19:00   ` Jim Mattson
2019-11-18 18:17 ` [PATCH 3/5] KVM: x86: implement MSR_IA32_TSX_CTRL effect on CPUID Paolo Bonzini
2019-11-19 20:02   ` Jim Mattson
2019-11-18 18:17 ` [PATCH 4/5] KVM: vmx: implement MSR_IA32_TSX_CTRL disable RTM functionality Paolo Bonzini
2019-11-19 21:06   ` Jim Mattson
2019-11-20 12:21     ` Paolo Bonzini
2019-12-04 23:49   ` Jim Mattson
2019-12-05 10:16     ` Paolo Bonzini
2019-11-18 18:17 ` [PATCH 5/5] KVM: vmx: use MSR_IA32_TSX_CTRL to hard-disable TSX on guest that lack it Paolo Bonzini
2019-11-21  2:22   ` Eduardo Habkost
2019-11-21  9:05     ` Paolo Bonzini [this message]

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=4a820b71-79eb-7d71-9cd2-93954cefcdd2@redhat.com \
    --to=pbonzini@redhat.com \
    --cc=ehabkost@redhat.com \
    --cc=jmattson@google.com \
    --cc=kvm@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=sean.j.christopherson@intel.com \
    --subject='Re: [PATCH 5/5] KVM: vmx: use MSR_IA32_TSX_CTRL to hard-disable TSX on guest that lack it' \
    /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

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).