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Date: Tue, 5 Nov 2019 01:47:52 +0000
From: "Moger, Babu" <Babu.Moger@....com>
To: Sean Christopherson <sean.j.christopherson@...el.com>
CC: "tglx@...utronix.de" <tglx@...utronix.de>,
"mingo@...hat.com" <mingo@...hat.com>,
"bp@...en8.de" <bp@...en8.de>, "hpa@...or.com" <hpa@...or.com>,
"pbonzini@...hat.com" <pbonzini@...hat.com>,
"rkrcmar@...hat.com" <rkrcmar@...hat.com>,
"vkuznets@...hat.com" <vkuznets@...hat.com>,
"wanpengli@...cent.com" <wanpengli@...cent.com>,
"jmattson@...gle.com" <jmattson@...gle.com>,
"x86@...nel.org" <x86@...nel.org>,
"joro@...tes.org" <joro@...tes.org>,
"luto@...nel.org" <luto@...nel.org>,
"zohar@...ux.ibm.com" <zohar@...ux.ibm.com>,
"yamada.masahiro@...ionext.com" <yamada.masahiro@...ionext.com>,
"nayna@...ux.ibm.com" <nayna@...ux.ibm.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"kvm@...r.kernel.org" <kvm@...r.kernel.org>
Subject: RE: [PATCH v2] x86/Kconfig: Rename UMIP config parameter
> -----Original Message-----
> From: Sean Christopherson <sean.j.christopherson@...el.com>
> Sent: Monday, November 4, 2019 3:49 PM
> To: Moger, Babu <Babu.Moger@....com>
> Cc: tglx@...utronix.de; mingo@...hat.com; bp@...en8.de; hpa@...or.com;
> pbonzini@...hat.com; rkrcmar@...hat.com; vkuznets@...hat.com;
> wanpengli@...cent.com; jmattson@...gle.com; x86@...nel.org;
> joro@...tes.org; luto@...nel.org; zohar@...ux.ibm.com;
> yamada.masahiro@...ionext.com; nayna@...ux.ibm.com; linux-
> kernel@...r.kernel.org; kvm@...r.kernel.org
> Subject: Re: [PATCH v2] x86/Kconfig: Rename UMIP config parameter
>
> On Mon, Nov 04, 2019 at 08:50:51PM +0000, Moger, Babu wrote:
> > AMD 2nd generation EPYC processors support the UMIP (User-Mode
> > Instruction Prevention) feature. So, rename X86_INTEL_UMIP to
> > generic X86_UMIP and modify the text to cover both Intel and AMD.
>
> There's a similar comment in the umip.c documentation that needs to be
> updated, and a grammatical error that can be opportunistically fixed, i.e.
>
> * The feature User-Mode Instruction Prevention present in recent Intel
> * processor
>
> to
>
> * The feature User-Mode Instruction Prevention present in recent x86
> * processors
>
Sure.
>
> IMO, the whole opening paragraph of the umip.c docs is weirdly worded and
> could be rewritten to something similar to the Kconfig help text, e.g.
>
> * User-Mode Instruction Prevention is a security feature present in recent x86
> * processors that, when enabled, prevents a group of instructions (SGDT, SIDT,
> * SLDT, SMSW and STR) from being run in user mode by issuing a general
> * protection fault if the instruction is executed with CPL > 0.
Sure. Will update it. Will add as patch #2 as this is separate from config file.
>
> >
> > Signed-off-by: Babu Moger <babu.moger@....com>
> > ---
> > v2:
> > Learned that for the hardware that support UMIP, we dont need to
> > emulate. Removed the emulation related code and just submitting
> > the config changes.
> >
> > arch/x86/Kconfig | 8 ++++----
> > arch/x86/include/asm/disabled-features.h | 2 +-
> > arch/x86/include/asm/umip.h | 4 ++--
> > arch/x86/kernel/Makefile | 2 +-
> > 4 files changed, 8 insertions(+), 8 deletions(-)
> >
> > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> > index d6e1faa28c58..821b7cebff31 100644
> > --- a/arch/x86/Kconfig
> > +++ b/arch/x86/Kconfig
> > @@ -1880,13 +1880,13 @@ config X86_SMAP
> >
> > If unsure, say Y.
> >
> > -config X86_INTEL_UMIP
> > +config X86_UMIP
> > def_bool y
> > - depends on CPU_SUP_INTEL
> > - prompt "Intel User Mode Instruction Prevention" if EXPERT
> > + depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
> > + prompt "User Mode Instruction Prevention" if EXPERT
> > ---help---
> > The User Mode Instruction Prevention (UMIP) is a security
>
> Maybe opportunistically drop "The"?
Sure.
>
> > - feature in newer Intel processors. If enabled, a general
> > + feature in newer x86 processors. If enabled, a general
> > protection fault is issued if the SGDT, SLDT, SIDT, SMSW
> > or STR instructions are executed in user mode. These instructions
> > unnecessarily expose information about the hardware state.
> > diff --git a/arch/x86/include/asm/disabled-features.h
> b/arch/x86/include/asm/disabled-features.h
> > index a5ea841cc6d2..8e1d0bb46361 100644
> > --- a/arch/x86/include/asm/disabled-features.h
> > +++ b/arch/x86/include/asm/disabled-features.h
> > @@ -22,7 +22,7 @@
> > # define DISABLE_SMAP (1<<(X86_FEATURE_SMAP & 31))
> > #endif
> >
> > -#ifdef CONFIG_X86_INTEL_UMIP
> > +#ifdef CONFIG_X86_UMIP
> > # define DISABLE_UMIP 0
> > #else
> > # define DISABLE_UMIP (1<<(X86_FEATURE_UMIP & 31))
> > diff --git a/arch/x86/include/asm/umip.h b/arch/x86/include/asm/umip.h
> > index db43f2a0d92c..aeed98c3c9e1 100644
> > --- a/arch/x86/include/asm/umip.h
> > +++ b/arch/x86/include/asm/umip.h
> > @@ -4,9 +4,9 @@
> > #include <linux/types.h>
> > #include <asm/ptrace.h>
> >
> > -#ifdef CONFIG_X86_INTEL_UMIP
> > +#ifdef CONFIG_X86_UMIP
> > bool fixup_umip_exception(struct pt_regs *regs);
> > #else
> > static inline bool fixup_umip_exception(struct pt_regs *regs) { return false; }
> > -#endif /* CONFIG_X86_INTEL_UMIP */
> > +#endif /* CONFIG_X86_UMIP */
> > #endif /* _ASM_X86_UMIP_H */
> > diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
> > index 3578ad248bc9..52ce1e239525 100644
> > --- a/arch/x86/kernel/Makefile
> > +++ b/arch/x86/kernel/Makefile
> > @@ -134,7 +134,7 @@ obj-$(CONFIG_EFI) += sysfb_efi.o
> > obj-$(CONFIG_PERF_EVENTS) += perf_regs.o
> > obj-$(CONFIG_TRACING) += tracepoint.o
> > obj-$(CONFIG_SCHED_MC_PRIO) += itmt.o
> > -obj-$(CONFIG_X86_INTEL_UMIP) += umip.o
> > +obj-$(CONFIG_X86_UMIP) += umip.o
> >
> > obj-$(CONFIG_UNWINDER_ORC) += unwind_orc.o
> > obj-$(CONFIG_UNWINDER_FRAME_POINTER) += unwind_frame.o
> >
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