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([2600:1010:b012:ea6:dc7:7fe:8643:2c24]) by smtp.gmail.com with ESMTPSA id e189sm41433049pfa.4.2018.01.31.14.53.56 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 31 Jan 2018 14:53:56 -0800 (PST) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (1.0) Subject: Re: [PATCH v5 4/5] KVM: VMX: Allow direct access to MSR_IA32_SPEC_CTRL From: Andy Lutomirski X-Mailer: iPhone Mail (15C202) In-Reply-To: Date: Wed, 31 Jan 2018 14:53:55 -0800 Cc: David Woodhouse , Paolo Bonzini , KarimAllah Ahmed , KarimAllah Ahmed , kvm list , LKML , the arch/x86 maintainers , Asit Mallick , Arjan Van De Ven , Dave Hansen , Andi Kleen , Andrea Arcangeli , Linus Torvalds , Tim Chen , Thomas Gleixner , Dan Williams , Jun Nakajima , Greg KH , Andy Lutomirski , Ashok Raj Content-Transfer-Encoding: quoted-printable Message-Id: References: <1517427467-28567-1-git-send-email-karahmed@amazon.de> <1517427467-28567-5-git-send-email-karahmed@amazon.de> <06cb88da-f355-41ed-380f-7daa8ddf6159@amazon.com> <67dca2bb-1298-c7fa-f681-018e4edc6725@redhat.com> <16d89e09-fbfc-4a08-00a6-40cfb4776018@redhat.com> <1517435981.18619.215.camel@infradead.org> To: Jim Mattson Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Jan 31, 2018, at 2:06 PM, Jim Mattson wrote: >=20 >> On Wed, Jan 31, 2018 at 1:59 PM, David Woodhouse wr= ote: >> I'm actually working on IBRS_ALL at the moment. >>=20 >> I was tempted to *not* let the guests turn it off. Expose SPEC_CTRL but >> just make it a no-op. >=20 > Maybe we could convince Intel to add a LOCK bit to IA32_SPEC_CTRL like > the one in IA32_FEATURE_CONTROL. Please no. Some BIOS vendor is going to lock it to zero to win some silly b= enchmark.