Subject: Re: [PATCH 6/7] x86/svm: Set IBPB when running a different VCPU
To: Jim Mattson <jmattson@google.com>,
        Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>,
        Liran Alon <liran.alon@oracle.com>, dwmw@amazon.co.uk,
        bp@alien8.de, aliguori@amazon.com,
        Tom Lendacky <thomas.lendacky@amd.com>,
        LKML <linux-kernel@vger.kernel.org>,
        kvm list <kvm@vger.kernel.org>
References: <a8eef7f8-98f8-4ff1-a05f-6b5258dd3a4d@default>
 <b0f1aadc-2d07-d9a5-851c-081914a564bc@linux.intel.com>
 <74e86dd8-804e-c9f2-098f-773283ac7065@redhat.com>
 <ed3fce02-8928-a45c-7360-1d42ed52d730@linux.intel.com>
 <1255f660-55c5-86f0-07d0-b5846af35c4a@redhat.com>
 <20180109203909.GG19756@char.us.oracle.com>
 <20180109204715.GL19756@char.us.oracle.com>
 <CALMp9eTsNSFgrZWWN9BeeTHuGdWXHvC1Db71nnWcVKxz7nnVrw@mail.gmail.com>
From: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <705f09f9-843f-97cb-4d4b-4b6818fcca7a@redhat.com>
Date: Tue, 9 Jan 2018 22:42:46 +0100
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101
 Thunderbird/52.5.0
MIME-Version: 1.0
In-Reply-To: <CALMp9eTsNSFgrZWWN9BeeTHuGdWXHvC1Db71nnWcVKxz7nnVrw@mail.gmail.com>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org

On 09/01/2018 21:57, Jim Mattson wrote:
> Before VM-entry, don't we need to flush the BHB and the RSB to avoid
> revealing KASLR information to the guest? (Thanks to Liran for
> pointing this out.)

I don't know how you flush the BHB?  As to the RSB, that would also be
part of generic Linux code so I've not included it yet in this series
which was mostly about the new MSRs and CPUID bits.

Paolo