linux-kernel - Re: [PATCH 8/9] x86/hreset: Configure history reset

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Message-ID: <20240204035552.GC26316@ranerica-svr.sc.intel.com>
Date: Sat, 3 Feb 2024 19:55:52 -0800
From: Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
To: Borislav Petkov <bp@...en8.de>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Len Brown <len.brown@...el.com>,
	Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
	Stanislaw Gruszka <stanislaw.gruszka@...ux.intel.com>,
	Zhao Liu <zhao1.liu@...el.com>,
	Zhuocheng Ding <zhuocheng.ding@...el.com>, x86@...nel.org,
	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
	Zhao Liu <zhao1.liu@...ux.intel.com>
Subject: Re: [PATCH 8/9] x86/hreset: Configure history reset

On Sat, Feb 03, 2024 at 10:38:57AM +0100, Borislav Petkov wrote:
> On Fri, Feb 02, 2024 at 08:05:14PM -0800, Ricardo Neri wrote:
> > +static __always_inline void setup_hreset(struct cpuinfo_x86 *c)
> > +{
> > +	if (!cpu_feature_enabled(X86_FEATURE_HRESET))
> > +		return;
> > +
> > +	/*
> > +	 * Use on all CPUs the hardware history features that the boot
> > +	 * CPU supports.
> > +	 */
> > +	if (c == &boot_cpu_data)
> > +		hardware_history_features = cpuid_ebx(0x20);
> 
> That's not what this does - that sets hardware_history_features on the
> BSP.

I meant to say that we will use the features that the BSP supports and
use them to configure all other CPUs. I will reword the comment to make
this clear.

> 
> Why isn't this whole thing called in bsp_init_intel()?

The register MSR_IA32_HW_HRESET_ENABLE needs to be configured on each CPU.

I can set hardware_history_features from bsp_init_intel() but I still
need to call setup_hreset() on every CPU.