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Wed, 09 Oct 2019 15:50:11 -0700 (PDT) Received: from [192.168.10.150] ([93.56.166.5]) by smtp.gmail.com with ESMTPSA id o1sm5141619wrs.78.2019.10.09.15.50.10 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 09 Oct 2019 15:50:10 -0700 (PDT) Subject: Re: [PATCH AUTOSEL 5.3 28/68] KVM: x86: Expose XSAVEERPTR to the guest To: Sebastian Andrzej Siewior Cc: Sasha Levin , linux-kernel@vger.kernel.org, stable@vger.kernel.org, kvm@vger.kernel.org References: <20191009170547.32204-1-sashal@kernel.org> <20191009170547.32204-28-sashal@kernel.org> <05acd554-dd0a-d7cd-e17c-90627fa0ec67@redhat.com> <20191009214048.irolhz4rwfdiqf2e@linutronix.de> From: Paolo Bonzini Openpgp: preference=signencrypt Message-ID: <7119916d-462e-8ba8-300c-c165d9df045a@redhat.com> Date: Thu, 10 Oct 2019 00:50:09 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20191009214048.irolhz4rwfdiqf2e@linutronix.de> Content-Language: en-US X-MC-Unique: Dy8fMBZjMM6iVR-3T-xWIw-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/10/19 23:40, Sebastian Andrzej Siewior wrote: >>> =09const u32 kvm_cpuid_8000_0008_ebx_x86_features =3D >>> +=09=09F(XSAVEERPTR) | >>> =09=09F(WBNOINVD) | F(AMD_IBPB) | F(AMD_IBRS) | F(AMD_SSBD) | F(VIRT_S= SBD) | >>> =09=09F(AMD_SSB_NO) | F(AMD_STIBP) | F(AMD_STIBP_ALWAYS_ON); >>> =20 >>> >> Yet another example of a patch that shouldn't be stable material (in >> this case it's fine, but there can certainly be cases where just adding >> a single flag depends on core kernel changes). >=20 > Also, taking advantage of this feature requires changes which just > landed in qemu's master branch. That's not a big deal, every QEMU supports every kernel and vice versa. Paolo