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([2001:b07:6468:f312:b20a:b600:521c:512d]) by smtp.gmail.com with ESMTPSA id f14sm11401536wme.22.2020.09.19.08.09.10 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 19 Sep 2020 08:09:10 -0700 (PDT) Subject: Re: [PATCH v4 2/2] KVM: nSVM: implement ondemand allocation of the nested state To: Sean Christopherson , Maxim Levitsky Cc: kvm@vger.kernel.org, Vitaly Kuznetsov , Ingo Molnar , Wanpeng Li , "H. Peter Anvin" , Borislav Petkov , Jim Mattson , Joerg Roedel , "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" , linux-kernel@vger.kernel.org, Thomas Gleixner References: <20200917101048.739691-1-mlevitsk@redhat.com> <20200917101048.739691-3-mlevitsk@redhat.com> <20200917162942.GE13522@sjchrist-ice> From: Paolo Bonzini Message-ID: Date: Sat, 19 Sep 2020 17:09:09 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: <20200917162942.GE13522@sjchrist-ice> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 17/09/20 18:29, Sean Christopherson wrote: >> + vcpu->arch.efer = old_efer; >> + kvm_make_request(KVM_REQ_OUT_OF_MEMORY, vcpu); > I really dislike KVM_REQ_OUT_OF_MEMORY. It's redundant with -ENOMEM and > creates a huge discrepancy with respect to existing code, e.g. nVMX returns > -ENOMEM in a similar situation. Maxim, your previous version was adding some error handling to kvm_x86_ops.set_efer. I don't remember what was the issue; did you have any problems propagating all the errors up to KVM_SET_SREGS (easy), kvm_set_msr (harder) etc.? Paolo