linux-kernel - Re: [RFC PATCH V6 04/14] x86/sev: optimize system vector processing invoked from #HV exception

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Date:   Wed, 17 May 2023 21:28:56 +0800
From:   Tianyu Lan <ltykernel@...il.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     luto@...nel.org, tglx@...utronix.de, mingo@...hat.com,
        bp@...en8.de, dave.hansen@...ux.intel.com, x86@...nel.org,
        hpa@...or.com, seanjc@...gle.com, pbonzini@...hat.com,
        jgross@...e.com, tiala@...rosoft.com, kirill@...temov.name,
        jiangshan.ljs@...group.com, ashish.kalra@....com,
        srutherford@...gle.com, akpm@...ux-foundation.org,
        anshuman.khandual@....com, pawan.kumar.gupta@...ux.intel.com,
        adrian.hunter@...el.com, daniel.sneddon@...ux.intel.com,
        alexander.shishkin@...ux.intel.com, sandipan.das@....com,
        ray.huang@....com, brijesh.singh@....com, michael.roth@....com,
        thomas.lendacky@....com, venu.busireddy@...cle.com,
        sterritt@...gle.com, tony.luck@...el.com, samitolvanen@...gle.com,
        fenghua.yu@...el.com, pangupta@....com,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        linux-hyperv@...r.kernel.org, linux-arch@...r.kernel.org
Subject: Re: [RFC PATCH V6 04/14] x86/sev: optimize system vector processing
 invoked from #HV exception

On 5/16/2023 6:23 PM, Peter Zijlstra wrote:
>> -				panic("Unexpected vector %d\n", vector);
>> -				unreachable();
>> +			if (!(sysvec_table[pending_events.vector - FIRST_SYSTEM_VECTOR])) {
>> +				WARN(1, "system vector entry 0x%x is NULL\n",
>> +				     pending_events.vector);
>> +			} else {
>> +				(*sysvec_table[pending_events.vector - FIRST_SYSTEM_VECTOR])(regs);
>>   			}
>>   		} else {
>>   			common_interrupt(regs, pending_events.vector);
> But your code replace direct calls with an indirect call. Now AFAIK,
> this SNP shit came with Zen3, and Zen3 still uses retpolines for
> indirect calls.
> 
> Can you connect the dots?


The title is no exact and will update in the next version. Thanks.