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[213.175.37.10]) by smtp.gmail.com with ESMTPSA id z19sm4455606wmi.43.2020.02.25.07.09.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 25 Feb 2020 07:09:49 -0800 (PST) From: Vitaly Kuznetsov To: Paolo Bonzini , Sean Christopherson Cc: Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 02/61] KVM: x86: Refactor loop around do_cpuid_func() to separate helper In-Reply-To: <04fb4fe9-017a-dcbb-6f18-0f6fd970bc99@redhat.com> References: <20200201185218.24473-1-sean.j.christopherson@intel.com> <20200201185218.24473-3-sean.j.christopherson@intel.com> <87sgjng3ru.fsf@vitty.brq.redhat.com> <20200207195301.GM2401@linux.intel.com> <04fb4fe9-017a-dcbb-6f18-0f6fd970bc99@redhat.com> Date: Tue, 25 Feb 2020 16:09:48 +0100 Message-ID: <87zhd6k8jn.fsf@vitty.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Paolo Bonzini writes: > On 07/02/20 20:53, Sean Christopherson wrote: >> >>> 2) Return -EINVAL instead. >> I agree that it _should_ be -EINVAL, but I just don't think it's worth >> the possibility of breaking (stupid) userspace that was doing something >> like: >> >> for (i = 0; i < max_cpuid_size; i++) { >> cpuid.nent = i; >> >> r = ioctl(fd, KVM_GET_SUPPORTED_CPUID, &cpuid); >> if (!r || r != -E2BIG) >> break; >> } >> > > Apart from the stupidity of the above case, why would it be EINVAL? > I suggested -EINVAL because issuing KVM_GET_SUPPORTED_CPUID with nent=0 looks more like a completely invalid input and not 'too many entries'(-E2BIG) to me (but -E2BIG is already there, let's keep it, it's not a big deal). > I can do the change to drop the initializer when applying. We're agreed with Sean on a few cosmetic changes in other patches of this series, wait for v2) -- Vitaly