linux-kernel - Re: [PATCH v6 4/5] KVM: VMX: Allow direct access to MSR_IA32_SPEC

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Date:   Fri, 02 Feb 2018 18:05:54 +0000
From:   David Woodhouse <dwmw2@...radead.org>
To:     Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        KarimAllah Ahmed <karahmed@...zon.de>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org, x86@...nel.org,
        Asit Mallick <asit.k.mallick@...el.com>,
        Arjan Van De Ven <arjan.van.de.ven@...el.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Dan Williams <dan.j.williams@...el.com>,
        Jun Nakajima <jun.nakajima@...el.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Greg KH <gregkh@...uxfoundation.org>,
        Andy Lutomirski <luto@...nel.org>,
        Ashok Raj <ashok.raj@...el.com>
Subject: Re: [PATCH v6 4/5] KVM: VMX: Allow direct access to
 MSR_IA32_SPEC_CTRL

On Fri, 2018-02-02 at 12:53 -0500, Konrad Rzeszutek Wilk wrote:
> .snip..
> > 
> > @@ -1913,6 +1914,29 @@ static void update_exception_bitmap(struct
> > kvm_vcpu *vcpu)
> >  }
> >  
> >  /*
> > + * Check if MSR is intercepted for currently loaded MSR bitmap.
> > + */
> > +static bool msr_write_intercepted(struct kvm_vcpu *vcpu, u32 msr)
> > +{
> > +	unsigned long *msr_bitmap;
> > +	int f = sizeof(unsigned long);
>
> unsigned int

$ grep -n 'f = sizeof' vmx.c
1934:	int f = sizeof(unsigned long);
5013:	int f = sizeof(unsigned long);
5048:	int f = sizeof(unsigned long);
5097:	int f = sizeof(unsigned long);

It sucks enough that we're doing this stuff repeatedly, and it's a
prime candidate for cleaning up, but I wasn't going to send Karim off
to bikeshed that today. Let's at least keep it consistent.

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