linux-kernel - Re: [PATCH RFC 4/7] x86/microcode/intel: Prepare for microcode staging

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Message-ID: <e9afefb7-3c4e-48ee-aab1-2f338c4e989d@intel.com>
Date: Mon, 4 Nov 2024 12:10:05 -0800
From: "Chang S. Bae" <chang.seok.bae@...el.com>
To: Dave Hansen <dave.hansen@...el.com>, Borislav Petkov <bp@...en8.de>
CC: <linux-kernel@...r.kernel.org>, <x86@...nel.org>, <tglx@...utronix.de>,
	<mingo@...hat.com>, <dave.hansen@...ux.intel.com>
Subject: Re: [PATCH RFC 4/7] x86/microcode/intel: Prepare for microcode
 staging

On 11/4/2024 10:34 AM, Chang S. Bae wrote:
> On 11/4/2024 8:08 AM, Dave Hansen wrote:
>> On 11/4/24 03:16, Borislav Petkov wrote:
>>> On Tue, Oct 01, 2024 at 09:10:39AM -0700, Chang S. Bae wrote:
>>>> +static inline u64 staging_addr(u32 cpu)
>>>> +{
>>>> +    u32 lo, hi;
>>>> +
>>>> +    rdmsr_on_cpu(cpu, MSR_IA32_MCU_STAGING_MBOX_ADDR, &lo, &hi);
>>>> +    return lo | ((u64)hi << 32);
>>>> +}
>>> A single usage site. Move its code there and get rid of the function.
>>
>> Yeah, and it'll look a lot nicer if you use:
>>
>>     rdmsrl_on_cpu(cpu, MSR_IA32_MCU_STAGING_MBOX_ADDR, &addr);
>>
>> and don't have to do the high/lo munging.
> 
> Oh, silly me missed this function. Thanks.

Okay, I took another look and found a similar case:

diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c
index 0f04feb6cafa..b942cd11e179 100644
--- a/drivers/cpufreq/acpi-cpufreq.c
+++ b/drivers/cpufreq/acpi-cpufreq.c
@@ -73,20 +73,17 @@ static unsigned int acpi_pstate_strict;

  static bool boost_state(unsigned int cpu)
  {
-       u32 lo, hi;
         u64 msr;

         switch (boot_cpu_data.x86_vendor) {
         case X86_VENDOR_INTEL:
         case X86_VENDOR_CENTAUR:
         case X86_VENDOR_ZHAOXIN:
-               rdmsr_on_cpu(cpu, MSR_IA32_MISC_ENABLE, &lo, &hi);
-               msr = lo | ((u64)hi << 32);
+               rdmsrl_on_cpu(cpu, MSR_IA32_MISC_ENABLE, &msr);
                 return !(msr & MSR_IA32_MISC_ENABLE_TURBO_DISABLE);
         case X86_VENDOR_HYGON:
         case X86_VENDOR_AMD:
-               rdmsr_on_cpu(cpu, MSR_K7_HWCR, &lo, &hi);
-               msr = lo | ((u64)hi << 32);
+               rdmsrl_on_cpu(cpu, MSR_K7_HWCR, &msr);
                 return !(msr & MSR_K7_HWCR_CPB_DIS);
         }
         return false;

I'll be following up with a patch to clean this up as well.

Thanks,
Chang