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From: Eduardo Habkost <ehabkost@redhat.com>
To: Paolo Bonzini <pbonzini@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: Wed, 20 Nov 2019 23:22:52 -0300	[thread overview]
Message-ID: <20191121022252.GX3812@habkost.net> (raw)
In-Reply-To: <1574101067-5638-6-git-send-email-pbonzini@redhat.com>

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?

-- 
Eduardo


  reply	other threads:[~2019-11-21  2:29 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 [this message]
2019-11-21  9:05     ` Paolo Bonzini

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