linux-kernel - Re: [PATCH v4] x86/bhyve: Detect FreeBSD Bhyve hypervisor

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Message-ID: <c4c167f335b0ee83275588aaf7346440f25ddce5.camel@infradead.org>
Date: Mon, 18 Aug 2025 12:03:10 +0100
From: David Woodhouse <dwmw2@...radead.org>
To: Borislav Petkov <bp@...en8.de>
Cc: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, 
 Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org, "H. Peter Anvin"
 <hpa@...or.com>, "Ahmed S. Darwish" <darwi@...utronix.de>,
 linux-kernel@...r.kernel.org, Konstantin Belousov <kib@....kiev.ua>,  John
 Baldwin <jhb@...ebsd.org>, "<cperciva@...snap.com>" <cperciva@...snap.com>
Subject: Re: [PATCH v4] x86/bhyve: Detect FreeBSD Bhyve hypervisor

On Mon, 2025-08-18 at 12:38 +0200, Borislav Petkov wrote:
> On Sat, Aug 16, 2025 at 11:06:32AM +0100, David Woodhouse wrote:
> > +static uint32_t bhyve_features(void)
> > +{
> > +	if (bhyve_cpuid_max < bhyve_cpuid_base | CPUID_BHYVE_FEATURES)
> 
> Forgot those parentheses again:
> 
> arch/x86/kernel/cpu/bhyve.c: In function ‘bhyve_features’:
> arch/x86/kernel/cpu/bhyve.c:42:29: warning: suggest parentheses around comparison in operand of ‘|’ [-Wparentheses]
>    42 |         if (bhyve_cpuid_max < bhyve_cpuid_base | CPUID_BHYVE_FEATURES)
>       |
> 
> Tztztz.
> 
> :-P

Doh! I actually just sent v3 again by accident. In v4 I had also
dropped the comment in bhyve_x2apic_available() since I'm not sure it's
true and it doesn't actually matter. But that's only cosmetic.

> I did the below. Ok?
> 
> static uint32_t bhyve_features(void)
> {
>         unsigned int cpuid_leaf = bhyve_cpuid_base | CPUID_BHYVE_FEATURES;
> 
>         if (bhyve_cpuid_max < cpuid_leaf)
>                 return 0;
> 
>         return cpuid_eax(cpuid_leaf);
> }
> 

Looks good, thanks.

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