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Date: Tue, 14 Feb 2017 19:57:21 -0800
From: Andy Lutomirski <luto@...capital.net>
To: Thomas Garnier <thgarnie@...gle.com>
Cc: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, 
	"H . Peter Anvin" <hpa@...or.com>, Andrey Ryabinin <aryabinin@...tuozzo.com>, 
	Alexander Potapenko <glider@...gle.com>, Dmitry Vyukov <dvyukov@...gle.com>, 
	Kees Cook <keescook@...omium.org>, Andy Lutomirski <luto@...nel.org>, Borislav Petkov <bp@...e.de>, 
	Paul Gortmaker <paul.gortmaker@...driver.com>, "Rafael J . Wysocki" <rjw@...ysocki.net>, 
	Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>, Jiri Kosina <jikos@...nel.org>, 
	Matt Fleming <matt@...eblueprint.co.uk>, Ard Biesheuvel <ard.biesheuvel@...aro.org>, 
	Boris Ostrovsky <boris.ostrovsky@...cle.com>, Juergen Gross <jgross@...e.com>, 
	Rusty Russell <rusty@...tcorp.com.au>, Peter Zijlstra <peterz@...radead.org>, 
	Christian Borntraeger <borntraeger@...ibm.com>, "Luis R . Rodriguez" <mcgrof@...nel.org>, 
	He Chen <he.chen@...ux.intel.com>, Brian Gerst <brgerst@...il.com>, 
	Stanislaw Gruszka <sgruszka@...hat.com>, Arnd Bergmann <arnd@...db.de>, 
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	Tim Chen <tim.c.chen@...ux.intel.com>, Rik van Riel <riel@...hat.com>, 
	Andi Kleen <ak@...ux.intel.com>, Jiri Olsa <jolsa@...hat.com>, 
	Michael Ellerman <mpe@...erman.id.au>, Joerg Roedel <joro@...tes.org>, 
	Paolo Bonzini <pbonzini@...hat.com>, Radim Krčmář <rkrcmar@...hat.com>, 
	X86 ML <x86@...nel.org>, 
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, kasan-dev <kasan-dev@...glegroups.com>, 
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>, 
	"linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>, 
	"xen-devel@...ts.xenproject.org" <xen-devel@...ts.xenproject.org>, lguest@...ts.ozlabs.org, 
	kvm list <kvm@...r.kernel.org>, 
	"kernel-hardening@...ts.openwall.com" <kernel-hardening@...ts.openwall.com>
Subject: Re: [PATCH v3 4/4] KVM: VMX: Simplify segment_base

On Tue, Feb 14, 2017 at 11:42 AM, Thomas Garnier <thgarnie@...gle.com> wrote:
> The KVM segment_base function is confusing. This patch replaces integers
> with appropriate flags, simplify constructs and add comments.

It could pay to put this first in the series, but last is probably fine, too.

>
> Signed-off-by: Thomas Garnier <thgarnie@...gle.com>
> ---
> Based on next-20170213
> ---
>  arch/x86/kvm/vmx.c | 26 ++++++++++++++++++--------
>  1 file changed, 18 insertions(+), 8 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 99167f20bc34..edb8326108dd 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -2062,25 +2062,35 @@ static unsigned long segment_base(u16 selector)
>         struct desc_struct *d;
>         unsigned long table_base;

This should go away IMO.  It should be struct desc_struct *table;

> +               table_base = get_current_gdt_rw_vaddr();

Then this can go away, too, and you can stop having the silly
get_current_gdt_rw_vaddr() function at all.

> +       d = (struct desc_struct *)table_base + (selector >> 3);

And this cast goes away too.

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