linux-kernel - Re: [PATCH v2 03/12] x86/kvm: Remove the KVM private read

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Message-ID: <281800ab-30bb-4939-8f20-0993a1e6b0f3@suse.com>
Date: Wed, 1 Oct 2025 11:14:36 +0200
From: Jürgen Groß <jgross@...e.com>
To: Sean Christopherson <seanjc@...gle.com>
Cc: linux-kernel@...r.kernel.org, x86@...nel.org, kvm@...r.kernel.org,
 xin@...or.com, Paolo Bonzini <pbonzini@...hat.com>,
 Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
 Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>,
 "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH v2 03/12] x86/kvm: Remove the KVM private read_msr()
 function

On 30.09.25 18:04, Sean Christopherson wrote:
> For the scope:
> 
>    KVM: x86:
> 
> because x86/kvm is specifically used for guest-side code.

Okay, will change that.

> 
> On Tue, Sep 30, 2025, Juergen Gross wrote:
>> Instead of having a KVM private read_msr() function, just use rdmsrq().
>>
>> Signed-off-by: Juergen Gross <jgross@...e.com>
>> ---
>> V2:
>> - remove the helper and use rdmsrq() directly (Sean Christopherson)
>> ---
>>   arch/x86/include/asm/kvm_host.h | 10 ----------
>>   arch/x86/kvm/vmx/vmx.c          |  4 ++--
>>   2 files changed, 2 insertions(+), 12 deletions(-)
>>
>> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
>> index f19a76d3ca0e..aed754dda1a3 100644
>> --- a/arch/x86/include/asm/kvm_host.h
>> +++ b/arch/x86/include/asm/kvm_host.h
>> @@ -2296,16 +2296,6 @@ static inline void kvm_load_ldt(u16 sel)
>>   	asm("lldt %0" : : "rm"(sel));
>>   }
>>   
>> -#ifdef CONFIG_X86_64
>> -static inline unsigned long read_msr(unsigned long msr)
>> -{
>> -	u64 value;
>> -
>> -	rdmsrq(msr, value);
>> -	return value;
>> -}
>> -#endif
> 
> Gah, the same commit[*] that added a wrmsrns() use also added a read_msr().  Sorry :-(
> 
> [*] 65391feb042b ("KVM: VMX: Add host MSR read/write helpers to consolidate preemption handling")

Again, thanks for the heads up.


Juergen

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