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From: Thomas Gleixner <tglx@linutronix.de>
To: Dave Hansen <dave.hansen@linux.intel.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Andy Lutomirski <luto@kernel.org>, Ingo Molnar <mingo@kernel.org>,
	Borislav Petkov <bp@alien8.de>, Brian Gerst <brgerst@gmail.com>,
	Denys Vlasenko <dvlasenk@redhat.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Rik van Riel <riel@redhat.com>,
	daniel.gruss@iaik.tugraz.at, hughd@google.com,
	keescook@google.com, linux-mm@kvack.org,
	michael.schwarz@iaik.tugraz.at, moritz.lipp@iaik.tugraz.at,
	richard.fellner@student.tugraz.at
Subject: Re: [patch V2 5/5] x86/kaiser: Add boottime disable switch
Date: Mon, 27 Nov 2017 20:00:19 +0100 (CET)	[thread overview]
Message-ID: <alpine.DEB.2.20.1711271958450.2333@nanos> (raw)
In-Reply-To: <24359653-5b93-7146-8f65-ac38c3af0069@linux.intel.com>

On Mon, 27 Nov 2017, Dave Hansen wrote:

> On 11/26/2017 03:14 PM, Thomas Gleixner wrote:
> > --- a/security/Kconfig
> > +++ b/security/Kconfig
> > @@ -56,7 +56,7 @@ config SECURITY_NETWORK
> >  
> >  config KAISER
> >  	bool "Remove the kernel mapping in user mode"
> > -	depends on X86_64 && SMP && !PARAVIRT
> > +	depends on X86_64 && SMP && !PARAVIRT && JUMP_LABEL
> >  	help
> >  	  This feature reduces the number of hardware side channels by
> >  	  ensuring that the majority of kernel addresses are not mapped
> 
> One of the reasons for doing the runtime-disable was to get rid of the
> !PARAVIRT dependency.  I can add a follow-on here that will act as if we
> did "nokaiser" whenever Xen is in play so we can remove this dependency.
> 
> I just hope Xen is detectable early enough to do the static patching.

Yes, it is. I'm currently trying to figure out why it fails on a KVM guest.

If I boot with 'nokaiser' on the command line it works. If kaiser is
runtime enabled then some early klibc user space in the ramdisk
explodes. Not sure yet whats going on.

Thanks,

	tglx

WARNING: multiple messages have this Message-ID
From: Thomas Gleixner <tglx@linutronix.de>
To: Dave Hansen <dave.hansen@linux.intel.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Andy Lutomirski <luto@kernel.org>, Ingo Molnar <mingo@kernel.org>,
	Borislav Petkov <bp@alien8.de>, Brian Gerst <brgerst@gmail.com>,
	Denys Vlasenko <dvlasenk@redhat.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Rik van Riel <riel@redhat.com>,
	daniel.gruss@iaik.tugraz.at, hughd@google.com,
	keescook@google.com, linux-mm@kvack.org,
	michael.schwarz@iaik.tugraz.at, moritz.lipp@iaik.tugraz.at,
	richard.fellner@student.tugraz.at
Subject: Re: [patch V2 5/5] x86/kaiser: Add boottime disable switch
Date: Mon, 27 Nov 2017 20:00:19 +0100 (CET)	[thread overview]
Message-ID: <alpine.DEB.2.20.1711271958450.2333@nanos> (raw)
In-Reply-To: <24359653-5b93-7146-8f65-ac38c3af0069@linux.intel.com>

On Mon, 27 Nov 2017, Dave Hansen wrote:

> On 11/26/2017 03:14 PM, Thomas Gleixner wrote:
> > --- a/security/Kconfig
> > +++ b/security/Kconfig
> > @@ -56,7 +56,7 @@ config SECURITY_NETWORK
> >  
> >  config KAISER
> >  	bool "Remove the kernel mapping in user mode"
> > -	depends on X86_64 && SMP && !PARAVIRT
> > +	depends on X86_64 && SMP && !PARAVIRT && JUMP_LABEL
> >  	help
> >  	  This feature reduces the number of hardware side channels by
> >  	  ensuring that the majority of kernel addresses are not mapped
> 
> One of the reasons for doing the runtime-disable was to get rid of the
> !PARAVIRT dependency.  I can add a follow-on here that will act as if we
> did "nokaiser" whenever Xen is in play so we can remove this dependency.
> 
> I just hope Xen is detectable early enough to do the static patching.

Yes, it is. I'm currently trying to figure out why it fails on a KVM guest.

If I boot with 'nokaiser' on the command line it works. If kaiser is
runtime enabled then some early klibc user space in the ramdisk
explodes. Not sure yet whats going on.

Thanks,

	tglx

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  reply	other threads:[~2017-11-27 19:00 UTC|newest]

Thread overview: 64+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-26 23:14 [patch V2 0/5] x86/kaiser: Boot time disabling and debug support Thomas Gleixner
2017-11-26 23:14 ` Thomas Gleixner
2017-11-26 23:14 ` [patch V2 1/5] x86/kaiser: Respect disabled CPU features Thomas Gleixner
2017-11-26 23:14   ` Thomas Gleixner
2017-11-27  9:57   ` Peter Zijlstra
2017-11-27  9:57     ` Peter Zijlstra
2017-11-27 11:47     ` Thomas Gleixner
2017-11-27 11:47       ` Thomas Gleixner
2017-11-27 12:31       ` Brian Gerst
2017-11-27 12:31         ` Brian Gerst
2017-11-27 13:18         ` Thomas Gleixner
2017-11-27 13:18           ` Thomas Gleixner
2017-11-27 18:11   ` Dave Hansen
2017-11-27 18:11     ` Dave Hansen
2017-11-27 18:37     ` Kees Cook
2017-11-27 18:37       ` Kees Cook
2017-11-26 23:14 ` [patch V2 2/5] x86/kaiser: Simplify disabling of global pages Thomas Gleixner
2017-11-26 23:14   ` Thomas Gleixner
2017-11-27 11:49   ` Thomas Gleixner
2017-11-27 11:49     ` Thomas Gleixner
2017-11-27 18:15   ` Dave Hansen
2017-11-27 18:15     ` Dave Hansen
2017-11-27 20:28     ` Thomas Gleixner
2017-11-27 20:28       ` Thomas Gleixner
2017-11-26 23:14 ` [patch V2 3/5] x86/dump_pagetables: Check KAISER shadow page table for WX pages Thomas Gleixner
2017-11-26 23:14   ` Thomas Gleixner
2017-11-27 18:17   ` Dave Hansen
2017-11-27 18:17     ` Dave Hansen
2017-11-26 23:14 ` [patch V2 4/5] x86/mm/debug_pagetables: Allow dumping current pagetables Thomas Gleixner
2017-11-26 23:14   ` Thomas Gleixner
2017-11-27  9:41   ` Peter Zijlstra
2017-11-27  9:41     ` Peter Zijlstra
2017-11-27 10:06     ` [PATCH] vfs: Add PERM_* symbolic helpers for common file mode/permissions Ingo Molnar
2017-11-27 10:06       ` Ingo Molnar
2017-11-27 19:21       ` Linus Torvalds
2017-11-27 19:21         ` Linus Torvalds
2017-11-28 10:54         ` Ingo Molnar
2017-11-28 10:54           ` Ingo Molnar
2017-11-28 11:12         ` Ingo Molnar
2017-11-28 11:12           ` Ingo Molnar
2017-11-29  8:52           ` Michael Ellerman
2017-11-29  8:52             ` Michael Ellerman
2017-11-27 18:18   ` [patch V2 4/5] x86/mm/debug_pagetables: Allow dumping current pagetables Dave Hansen
2017-11-27 18:18     ` Dave Hansen
2017-11-26 23:14 ` [patch V2 5/5] x86/kaiser: Add boottime disable switch Thomas Gleixner
2017-11-26 23:14   ` Thomas Gleixner
2017-11-27  9:48   ` Peter Zijlstra
2017-11-27  9:48     ` Peter Zijlstra
2017-11-27 10:22     ` Peter Zijlstra
2017-11-27 10:22       ` Peter Zijlstra
2017-11-27 11:50       ` Thomas Gleixner
2017-11-27 11:50         ` Thomas Gleixner
2017-11-27 12:49         ` Peter Zijlstra
2017-11-27 12:49           ` Peter Zijlstra
2017-11-27 21:43       ` Peter Zijlstra
2017-11-27 21:43         ` Peter Zijlstra
2017-11-27 18:22   ` Dave Hansen
2017-11-27 18:22     ` Dave Hansen
2017-11-27 19:00     ` Thomas Gleixner [this message]
2017-11-27 19:00       ` Thomas Gleixner
2017-11-27 19:18       ` Josh Poimboeuf
2017-11-27 19:18         ` Josh Poimboeuf
2017-11-27 20:47         ` Thomas Gleixner
2017-11-27 20:47           ` Thomas Gleixner

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