Re: [Xen-devel] [PATCH 2/8] x86/hyperv: detect absolutely necessary MSRs

From: Jan Beulich <jbeulich@suse.com>
To: Wei Liu <wl@xen.org>
Cc: "Wei Liu" <liuwe@microsoft.com>,
	"Andrew Cooper" <andrew.cooper3@citrix.com>,
	"Michael Kelley" <mikelley@microsoft.com>,
	"Paul Durrant" <pdurrant@gmail.com>,
	"Xen Development List" <xen-devel@lists.xenproject.org>,
	"Roger Pau Monné" <roger.pau@citrix.com>
Subject: Re: [Xen-devel] [PATCH 2/8] x86/hyperv: detect absolutely necessary MSRs
Date: Fri, 3 Jan 2020 17:14:40 +0100	[thread overview]
Message-ID: <da233f18-0982-8356-ac2e-aeeb28bee007@suse.com> (raw)
In-Reply-To: <CACCGGhDpQ4Df9KcgeTY30XPri9cP+Nv=NZsm7oZA4J_Z7ZS_Jg@mail.gmail.com>

On 03.01.2020 12:01, Paul Durrant wrote:
> On Sun, 29 Dec 2019 at 18:34, Wei Liu <wl@xen.org> wrote:
>> --- a/xen/arch/x86/guest/hyperv/hyperv.c
>> +++ b/xen/arch/x86/guest/hyperv/hyperv.c
>> @@ -32,6 +32,8 @@ static const struct hypervisor_ops ops = {
>>  const struct hypervisor_ops *__init hyperv_probe(void)
>>  {
>>      uint32_t eax, ebx, ecx, edx;
>> +    uint64_t required_msrs = HV_X64_MSR_HYPERCALL_AVAILABLE |
>> +        HV_X64_MSR_VP_INDEX_AVAILABLE;
>>
>>      cpuid(0x40000000, &eax, &ebx, &ecx, &edx);
>>      if ( !((ebx == 0x7263694d) &&  /* "Micr" */
>> @@ -57,6 +59,15 @@ const struct hypervisor_ops *__init hyperv_probe(void)
>>      ms_hyperv.max_vp_index = eax;
>>      ms_hyperv.max_lp_index = ebx;
>>
>> +    if ( (ms_hyperv.features & required_msrs) != required_msrs )
>> +    {
>> +        /* Oops, required MSRs are not available. Treat this as
>> +         * "Hyper-V is not available".
>> +         */
> 
> That block comment violates default coding style.

And with it corrected
Acked-by: Jan Beulich <jbeulich@suse.com>

Jan

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