Re: [PATCH v6 5/5] KVM: SVM: Allow direct access to MSR_IA32_SPEC_CTRL

[Konrad Rzeszutek Wilk]

On Thu, Feb 01, 2018 at 10:59:46PM +0100, KarimAllah Ahmed wrote:
> [ Based on a patch from Paolo Bonzini <pbonzini@xxxxxxxxxx> ]
> 
> ... basically doing exactly what we do for VMX:
> 
> - Passthrough SPEC_CTRL to guests (if enabled in guest CPUID)
> - Save and restore SPEC_CTRL around VMExit and VMEntry only if the guest
>   actually used it.
> 
> Cc: Asit Mallick <asit.k.mallick@xxxxxxxxx>
> Cc: Arjan Van De Ven <arjan.van.de.ven@xxxxxxxxx>
> Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
> Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Cc: Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx>
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
> Cc: Jun Nakajima <jun.nakajima@xxxxxxxxx>
> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> Cc: David Woodhouse <dwmw@xxxxxxxxxxxx>
> Cc: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>
> Cc: Andy Lutomirski <luto@xxxxxxxxxx>
> Cc: Ashok Raj <ashok.raj@xxxxxxxxx>
> Signed-off-by: KarimAllah Ahmed <karahmed@xxxxxxxxx>

Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> +	{ .index = MSR_IA32_SPEC_CTRL,			.always = false },


This .always = [false|true] field keeps throwing me off.

So glad: https://www.spinics.net/lists/kvm/msg161606.html explains it better.