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([2a10:bac0:b000:7318:7285:c2ff:fedd:7e3a]) by smtp.gmail.com with ESMTPSA id bi8-20020a05600c3d8800b00417e184dacbsm394768wmb.25.2024.04.11.00.34.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 11 Apr 2024 00:34:17 -0700 (PDT) Message-ID: <18b29bd6-5eb5-4344-b80f-f6a55c18b8ba@suse.com> Date: Thu, 11 Apr 2024 10:34:15 +0300 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] KVM: x86: Set BHI_NO in guest when host is not affected by BHI To: Alexandre Chartre , x86@kernel.org, kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org, daniel.sneddon@linux.intel.com, pawan.kumar.gupta@linux.intel.com, tglx@linutronix.de, konrad.wilk@oracle.com, peterz@infradead.org, gregkh@linuxfoundation.org, seanjc@google.com, andrew.cooper3@citrix.com, dave.hansen@linux.intel.com, kpsingh@kernel.org, longman@redhat.com, bp@alien8.de, pbonzini@redhat.com References: <20240411072445.522731-1-alexandre.chartre@oracle.com> From: Nikolay Borisov Content-Language: en-US In-Reply-To: <20240411072445.522731-1-alexandre.chartre@oracle.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 11.04.24 г. 10:24 ч., Alexandre Chartre wrote: > When a system is not affected by the BHI bug then KVM should > configure guests with BHI_NO to ensure they won't enable any > BHI mitigation. > > Signed-off-by: Alexandre Chartre > --- > arch/x86/kvm/x86.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 984ea2089efc..f43d3c15a6b7 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -1678,6 +1678,9 @@ static u64 kvm_get_arch_capabilities(void) > if (!boot_cpu_has_bug(X86_BUG_GDS) || gds_ucode_mitigated()) > data |= ARCH_CAP_GDS_NO; > > + if (!boot_cpu_has_bug(X86_BUG_BHI)) > + data |= ARCH_CAP_BHI_NO; > + But this is already handled since ARCH_CAP_BHI_NO is added to KVM_SUPPORTED_ARCH_CAP so when the host caps are read that bit is going to be set there, if it's set for the physical cpu of course. > return data; > } >