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Date:   Fri, 22 Sep 2023 18:41:55 +0000
From:   Wei Liu <wei.liu@kernel.org>
To:     Saurabh Sengar <ssengar@linux.microsoft.com>
Cc:     kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org,
        decui@microsoft.com, tglx@linutronix.de, mingo@redhat.com,
        bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org,
        hpa@zytor.com, linux-hyperv@vger.kernel.org,
        linux-kernel@vger.kernel.org, mikelley@microsoft.com,
        vkuznets@redhat.com, ssengar@microsoft.com
Subject: Re: [PATCH v3] x86/hyperv: Restrict get_vtl to only VTL platforms
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References: <1695182675-13405-1-git-send-email-ssengar@linux.microsoft.com>
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On Tue, Sep 19, 2023 at 09:04:35PM -0700, Saurabh Sengar wrote:
> When Linux runs in a non-default VTL (CONFIG_HYPERV_VTL_MODE=y),
> get_vtl() must never fail as its return value is used in negotiations
> with the host. In the more generic case, (CONFIG_HYPERV_VTL_MODE=n) the
> VTL is always zero so there's no need to do the hypercall.
> 
> Make get_vtl() BUG() in case of failure and put the implementation under
> "if IS_ENABLED(CONFIG_HYPERV_VTL_MODE)" to avoid the call altogether in
> the most generic use case.
> 
> Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
> Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>

Applied to hyperv-fixes. Thanks.