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

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Message-ID: <aNv_lWzVqycCUZIi@google.com>
Date: Tue, 30 Sep 2025 09:04:37 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Juergen Gross <jgross@...e.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

For the scope:

  KVM: x86:

because x86/kvm is specifically used for guest-side code.

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")