From mboxrd@z Thu Jan 1 00:00:00 1970 From: "rkrcmar@redhat.com" Subject: Re: [PATCH] KVM/X86: Check input sreg values before loading vcpu Date: Thu, 8 Mar 2018 17:15:36 +0100 Message-ID: <20180308161536.GH12290@flask> References: <1519714664-2649-1-git-send-email-Tianyu.Lan@microsoft.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "pbonzini@redhat.com" , "tglx@linutronix.de" , "mingo@redhat.com" , "hpa@zytor.com" , "x86@kernel.org" , "kvm@vger.kernel.org" , "linux-kernel@vger.kernel.org" To: Tianyu Lan Return-path: Content-Disposition: inline In-Reply-To: <1519714664-2649-1-git-send-email-Tianyu.Lan@microsoft.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org 2018-02-27 06:57+0000, Tianyu Lan: > From: Lan Tianyu > > This patch is to check sreg value first and then load vcpu in order > to avoid redundant loading/putting vcpu. > > Signed-off-by: Lan Tianyu > --- Patch "KVM: x86: KVM_CAP_SYNC_REGS" made significant changes to the sregs setter, so the patch cannot be applied in current form. I think that moving the X86_CR4_OSXSAVE check to guest_cpuid_has still makes sense, but avoiding the vcpu_load/put would produce worse code elsewhere and avoiding the load/put is not critical as any error is probably going to be the end for this VM. Thanks.