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[91.219.240.2]) by smtp.gmail.com with ESMTPSA id b14-20020a170906d10e00b006e803595901sm3641599ejz.172.2022.04.07.12.10.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 07 Apr 2022 12:10:18 -0700 (PDT) From: Vitaly Kuznetsov To: Sean Christopherson Cc: kvm@vger.kernel.org, Paolo Bonzini , Wanpeng Li , Jim Mattson , Naresh Kamboju , Maxim Levitsky , linux-kernel@vger.kernel.org Subject: Re: [PATCH] KVM: x86: hyper-v: Avoid writing to TSC page without an active vCPU In-Reply-To: References: <20220407154754.939923-1-vkuznets@redhat.com> Date: Thu, 07 Apr 2022 21:10:17 +0200 Message-ID: <87o81c7lra.fsf@redhat.com> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Sean Christopherson writes: > On Thu, Apr 07, 2022, Vitaly Kuznetsov wrote: >> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h >> index 676705ad1e23..3460bcd75bf2 100644 >> --- a/arch/x86/include/asm/kvm_host.h >> +++ b/arch/x86/include/asm/kvm_host.h >> @@ -979,10 +979,10 @@ enum hv_tsc_page_status { >> HV_TSC_PAGE_GUEST_CHANGED, >> /* TSC page MSR was written by KVM userspace, update pending */ >> HV_TSC_PAGE_HOST_CHANGED, >> + /* TSC page needs to be updated due to internal KVM changes */ >> + HV_TSC_PAGE_KVM_CHANGED, > > Why add KVM_CHANGED? I don't see any reason to differentiate between userspace > and KVM, and using KVM_CHANGED for the kvm_vm_ioctl_set_clock() case is wrong as > that is very much a userspace initiated update, not a KVM update. Indeed, there seems to be no benefit in differentiating between HV_TSC_PAGE_HOST_CHANGED and HV_TSC_PAGE_KVM_CHANGED. Let me retest without it, I'll be sending v2 shortly. > >> /* TSC page was properly set up and is currently active */ >> HV_TSC_PAGE_SET, >> - /* TSC page is currently being updated and therefore is inactive */ >> - HV_TSC_PAGE_UPDATING, >> /* TSC page was set up with an inaccessible GPA */ >> HV_TSC_PAGE_BROKEN, >> }; > -- Vitaly