Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:4 as permitted sender) client-ip=2620:137:e000::3:4;
From:   Thomas Gleixner <tglx@linutronix.de>
To:     "H. Peter Anvin" <hpa@zytor.com>, Xin Li <xin3.li@intel.com>,
        linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-edac@vger.kernel.org, linux-hyperv@vger.kernel.org,
        kvm@vger.kernel.org, xen-devel@lists.xenproject.org
Cc:     mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com,
        x86@kernel.org, luto@kernel.org, pbonzini@redhat.com,
        seanjc@google.com, peterz@infradead.org, jgross@suse.com,
        ravi.v.shankar@intel.com, mhiramat@kernel.org,
        andrew.cooper3@citrix.com, jiangshanlai@gmail.com,
        nik.borisov@suse.com
Subject: Re: [PATCH v11 35/37] x86/syscall: Split IDT syscall setup code
 into idt_syscall_init()
In-Reply-To: <D4167CD5-B619-448D-B660-24ABC0786E0A@zytor.com>
References: <20230923094212.26520-1-xin3.li@intel.com>
 <20230923094212.26520-36-xin3.li@intel.com>
 <D4167CD5-B619-448D-B660-24ABC0786E0A@zytor.com>
Date:   Thu, 28 Sep 2023 20:01:48 +0200
Message-ID: <87y1gqdvn7.ffs@tglx>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

On Mon, Sep 25 2023 at 09:07, H. Peter Anvin wrote:
> On September 23, 2023 2:42:10 AM PDT, Xin Li <xin3.li@intel.com> wrote:
>>+/* May not be marked __init: used by software suspend */
>>+void syscall_init(void)
>>+{
>>+	/* The default user and kernel segments */
>>+	wrmsr(MSR_STAR, 0, (__USER32_CS << 16) | __KERNEL_CS);
>>+
>>+	idt_syscall_init();
>>+}
>>+
>> #else	/* CONFIG_X86_64 */
>> 
>> #ifdef CONFIG_STACKPROTECTOR
>
> Am I missing something, or is this patch a noop?

Yes. It's a noop at this point. Later on it gains a

     if (!fred)
        idt_syscall_init();

Sure we could do

     if (!fred) {
     	write_msr(foo...);
        ...
     }

too, but I prefer the separation. No strong opinion though.

Thanks,

        tglx