linux-kernel - Re: [RFC PATCH V3 13/16] x86/sev: Add Check of #HV event in path

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <cdfe4403-edd9-f265-1ea3-2aa57c0edddc@gmail.com>
Date:   Fri, 10 Mar 2023 23:59:28 +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 13/16] x86/sev: Add Check of #HV event in path

On 3/9/2023 12:18 AM, Gupta, Pankaj wrote:
> On 3/1/2023 12:11 PM, Gupta, Pankaj wrote:
>> On 1/22/2023 3:46 AM, Tianyu Lan wrote:

>>> diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
>>> index a8862a2eff67..fe5e5e41433d 100644
>>> --- a/arch/x86/kernel/sev.c
>>> +++ b/arch/x86/kernel/sev.c
>>> @@ -179,6 +179,45 @@ void noinstr __sev_es_ist_enter(struct pt_regs 
>>> *regs)
>>>       this_cpu_write(cpu_tss_rw.x86_tss.ist[IST_INDEX_VC], new_ist);
>>>   }
>>> +static void do_exc_hv(struct pt_regs *regs)
>>> +{
>>> +    /* Handle #HV exception. */
>>> +}
>>> +
>>> +void check_hv_pending(struct pt_regs *regs)
>>> +{
>>> +    if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP))
>>> +        return;
>>> +
>>> +    if ((regs->flags & X86_EFLAGS_IF) == 0)
>>> +        return;
>>
>> Will this return and prevent guest from executing NMI's
>> while irqs are disabled?
> 
> I think we need to handle NMI's even when irqs are disabled.
> 

Yes, nice catch!

> As we reset "no_further_signal" in hv_raw_handle_exception()
> and return from check_hv_pending() when irqs are disabled, this
> can result in loss/delay of NMI event?

Will fix this in the next version.

Thanks.