linux-kernel - Re: [PATCH 2/6] kvm: x86: drop read_tsc

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Message-ID: <41e7b724-07dd-9c9d-3119-c12e50adbe44@redhat.com>
Date:   Mon, 19 Sep 2016 17:34:28 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Jim Mattson <jmattson@...gle.com>,
        Luiz Capitulino <lcapitulino@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Radim Krčmář <rkrcmar@...hat.com>,
        rostedt@...dmis.org, mhiramat@...nel.org, mtosatti@...hat.com
Subject: Re: [PATCH 2/6] kvm: x86: drop read_tsc_offset()



On 19/09/2016 17:30, Jim Mattson wrote:
> vmx_read_tsc_offset has a bug when running nested VMs.  It should really be:
> 
>        if (is_guest_mode(vcpu))
>                return to_vmx(vcpu)->nested.vmcs01_tsc_offset;
>        else
>                return vmcs_read64(TSC_OFFSET);
> 
> Perhaps a better name woulf be "vmx_get_l1_tsc_offset."

I agree, but doesn't this patch fix the bug too?

Paolo

> In any case, this does not seem consistent with vcpu->arch.tsc_offset.



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