linux-kernel - Re: [RFC PATCH v1 01/15] x86/msr: Replace __wrmsr() with native

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Message-ID: <9D15DE81-2E68-4FCD-A133-4963602E18C9@zytor.com>
Date: Mon, 31 Mar 2025 13:32:58 -0700
From: "H. Peter Anvin" <hpa@...or.com>
To: Ingo Molnar <mingo@...nel.org>, "Xin Li (Intel)" <xin@...or.com>
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Subject: Re: [RFC PATCH v1 01/15] x86/msr: Replace __wrmsr() with native_wrmsrl()

On March 31, 2025 3:17:30 AM PDT, Ingo Molnar <mingo@...nel.org> wrote:
>
>* Xin Li (Intel) <xin@...or.com> wrote:
>
>> -	__wrmsr      (MSR_AMD_DBG_EXTN_CFG, val | 3ULL << 3, val >> 32);
>> +	native_wrmsrl(MSR_AMD_DBG_EXTN_CFG, val | 3ULL << 3);
>
>This is an improvement.
>
>> -	__wrmsr      (MSR_IA32_PQR_ASSOC, rmid_p, plr->closid);
>> +	native_wrmsrl(MSR_IA32_PQR_ASSOC, (u64)plr->closid << 32 | rmid_p);
>
>> -	__wrmsr      (MSR_IA32_PQR_ASSOC, rmid_p, closid_p);
>> +	native_wrmsrl(MSR_IA32_PQR_ASSOC, (u64)closid_p << 32 | rmid_p);
>
>This is not an improvement.
>
>Please provide a native_wrmsrl() API variant where natural [rmid_p, closid_p]
>high/lo parameters can be used, without the shift-uglification...
>
>Thanks,
>
>	Ingo

Directing this question primarily to Ingo, who is more than anyone else the namespace consistency guardian:

On the subject of msr function naming ... *msrl() has always been misleading. The -l suffix usually means 32 bits; sometimes it means the C type "long" (which in the kernel is used instead of size_t/uintptr_t, which might end up being "fun" when 128-bit architectures appear some time this century), but for a fixed 64-but type we normally use -q.

Should we rename the *msrl() functions to *msrq() as part of this overhaul?