Message-ID: <432bb9b3-959e-1074-c0e6-a65ac46e489e@oracle.com>
Date:   Mon, 27 Feb 2023 08:52:05 -0500
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Subject: Re: [PATCH v3 05/12] x86/xen: set MTRR state when running as Xen PV
 initial domain
Content-Language: en-US
To:     Juergen Gross <jgross@suse.com>, linux-kernel@vger.kernel.org,
        x86@kernel.org
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        "H. Peter Anvin" <hpa@zytor.com>, xen-devel@lists.xenproject.org
References: <20230223093243.1180-1-jgross@suse.com>
 <20230223093243.1180-6-jgross@suse.com>
 <a7897030-d420-a741-074a-6e21e7c1629b@oracle.com>
 <58248946-f0ad-ae3b-57a6-f7c15fd35198@suse.com>
From:   Boris Ostrovsky <boris.ostrovsky@oracle.com>
In-Reply-To: <58248946-f0ad-ae3b-57a6-f7c15fd35198@suse.com>
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On 2/27/23 2:12 AM, Juergen Gross wrote:
> On 24.02.23 22:00, Boris Ostrovsky wrote:
>>
>> On 2/23/23 4:32 AM, Juergen Gross wrote:
>>> +
>>> +    for (reg = 0; reg < MTRR_MAX_VAR_RANGES; reg++) {
>>> +        op.u.read_memtype.reg = reg;
>>> +        if (HYPERVISOR_platform_op(&op))
>>> +            break;
>>
>>
>> If we fail on the first iteration, do we still want to mark MTRRs are enabled/set in mtrr_overwrite_state()?
> 
> Hmm, good idea.
> 
> I think we should just drop the call of mtrr_overwrite_state() in this
> case.


TBH I am not sure what the right way is to handle errors here. What if the hypercall fails on second iteration?


-boris