linux-kernel - Re: [PATCH v4 22/26] KVM: SVM: Use BIT() and GENMASK() for definitions in svm.h

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Message-ID: <aYVF0YfqlRktzM7S@google.com>
Date: Thu, 5 Feb 2026 17:37:21 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: Yosry Ahmed <yosry.ahmed@...ux.dev>
Cc: Paolo Bonzini <pbonzini@...hat.com>, kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 22/26] KVM: SVM: Use BIT() and GENMASK() for
 definitions in svm.h

On Thu, Jan 15, 2026, Yosry Ahmed wrote:
> Use BIT() and GENMASK() (and *_ULL() variants) to define the bitmasks in
> svm.h.

Oh, hey, just what I was talking about.  But why is this buried as patch 22/26?
AFAICT, it's got nothing to do with the rest of the series.

> Opportunistically switch the definitions of AVIC_ENABLE_{SHIFT/MASK}
> and X2APIC_MODE_{SHIFT/MASK}, as well as SVM_EVTINJ_VALID and
> SVM_EVTINJ_VALID_ERR, such that the bitmasks are defined in the correct
> order.
> 
> No functional change intended.
> 
> Signed-off-by: Yosry Ahmed <yosry.ahmed@...ux.dev>
> ---
>  arch/x86/include/asm/svm.h | 78 +++++++++++++++++++-------------------
>  1 file changed, 39 insertions(+), 39 deletions(-)
> 
> diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
> index 770c7aed5fa5..0bc26b2b3fd7 100644
> --- a/arch/x86/include/asm/svm.h
> +++ b/arch/x86/include/asm/svm.h
> @@ -189,39 +189,39 @@ struct __attribute__ ((__packed__)) vmcb_control_area {
>  #define V_TPR_MASK 0x0f
>  
>  #define V_IRQ_SHIFT 8
> -#define V_IRQ_MASK (1 << V_IRQ_SHIFT)
> +#define V_IRQ_MASK BIT(V_IRQ_SHIFT)

I vote (and if anyone disagrees, their vote doesn't count) to purge the _SHIFT
and _MASK crud.  There is zero reason to define the shifts.

And then when we rename, I would like to try and find better names, e.g. maybe
things like V_GIF and V_ENABLE_GIF_VIRTUALIZATION?

Anyways, that's partly why I asked why this patch is here.  If we're changing
things, then I'd like to do some cleanup.  But this series is already a chonker,
so I'd much prefer to do any cleanup in a separate series.