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([2001:b07:6468:f312:5e2c:eb9a:a8b6:fd3e]) by smtp.gmail.com with ESMTPSA id r19sm14422213ejr.55.2021.04.08.08.47.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 08 Apr 2021 08:47:17 -0700 (PDT) Subject: Re: [PATCH 6/7] KVM: SVM: hyper-v: Enlightened MSR-Bitmap support To: Vineeth Pillai , Lan Tianyu , Michael Kelley , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Wei Liu , Stephen Hemminger , Haiyang Zhang Cc: "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "K. Y. Srinivasan" , x86@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org References: <5cf935068a9539146e033276b6d9a6c9b1e42119.1617804573.git.viremana@linux.microsoft.com> From: Paolo Bonzini Message-ID: <58df22aa-5d2c-f99f-6dfb-9a8b4260dc21@redhat.com> Date: Thu, 8 Apr 2021 17:47:15 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.0 MIME-Version: 1.0 In-Reply-To: <5cf935068a9539146e033276b6d9a6c9b1e42119.1617804573.git.viremana@linux.microsoft.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 07/04/21 16:41, Vineeth Pillai wrote: > > +#if IS_ENABLED(CONFIG_HYPERV) > +static inline void hv_vmcb_dirty_nested_enlightenments(struct kvm_vcpu *vcpu) > +{ > + struct vmcb *vmcb = to_svm(vcpu)->vmcb; > + > + /* > + * vmcb can be NULL if called during early vcpu init. > + * And its okay not to mark vmcb dirty during vcpu init > + * as we mark it dirty unconditionally towards end of vcpu > + * init phase. > + */ > + if (vmcb && vmcb_is_clean(vmcb, VMCB_HV_NESTED_ENLIGHTENMENTS) && > + vmcb->hv_enlightenments.hv_enlightenments_control.msr_bitmap) > + vmcb_mark_dirty(vmcb, VMCB_HV_NESTED_ENLIGHTENMENTS); > +} In addition to what Vitaly said, can svm->vmcb really be NULL? If so it might be better to reorder initializations and skip the NULL check. Paolo