linux-kernel - Re: [RFC PATCH V3 16/16] x86/sev: Fix interrupt exit code paths from #HV exception

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Date:   Sat, 11 Mar 2023 00:02:55 +0800
From:   Tianyu Lan <ltykernel@...il.com>
To:     "Gupta, Pankaj" <pankaj.gupta@....com>, 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, peterz@...radead.org,
        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
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        linux-hyperv@...r.kernel.org, linux-arch@...r.kernel.org
Subject: Re: [RFC PATCH V3 16/16] x86/sev: Fix interrupt exit code paths from
 #HV exception

On 2/22/2023 12:44 AM, Gupta, Pankaj wrote:
>> @@ -2529,3 +2537,25 @@ static int __init snp_init_platform_device(void)
>>       return 0;
>>   }
>>   device_initcall(snp_init_platform_device);
>> +
>> +noinstr void irqentry_exit_hv_cond(struct pt_regs *regs, 
>> irqentry_state_t state)
>> +{
> 
> This code path is being called even for the guest without SNP. Ran
> a SEV guest and guest crashed in this code path. Checking & returning
> made guest (non SNP) to boot with some call traces. But this branch 
> needs to be avoided for non-SNP guests and host as well.
> 

Nice catch! I will fix it in the next version.

Thanks.