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Date:   Wed, 25 Oct 2023 11:15:15 +0300
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH v2 5/6] KVM: VMX: Use BT+JNC, i.e. EFLAGS.CF to select
 VMRESUME vs. VMLAUNCH
Content-Language: en-US
To:     Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>, x86@kernel.org,
        "H. Peter Anvin" <hpa@zytor.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Josh Poimboeuf <jpoimboe@kernel.org>,
        Andy Lutomirski <luto@kernel.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Sean Christopherson <seanjc@google.com>,
        Paolo Bonzini <pbonzini@redhat.com>, tony.luck@intel.com,
        ak@linux.intel.com, tim.c.chen@linux.intel.com
Cc:     linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
        kvm@vger.kernel.org,
        Alyssa Milburn <alyssa.milburn@linux.intel.com>,
        Daniel Sneddon <daniel.sneddon@linux.intel.com>,
        antonio.gomez.iglesias@linux.intel.com
References: <20231024-delay-verw-v2-0-f1881340c807@linux.intel.com>
 <20231024-delay-verw-v2-5-f1881340c807@linux.intel.com>
From:   Nikolay Borisov <nik.borisov@suse.com>
In-Reply-To: <20231024-delay-verw-v2-5-f1881340c807@linux.intel.com>
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On 24.10.23 г. 11:08 ч., Pawan Gupta wrote:
> From: Sean Christopherson <seanjc@google.com>
> 
> Use EFLAGS.CF instead of EFLAGS.ZF to track whether to use VMRESUME versus
> VMLAUNCH.  Freeing up EFLAGS.ZF will allow doing VERW, which clobbers ZF,
> for MDS mitigations as late as possible without needing to duplicate VERW
> for both paths.
> 
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>

Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>