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From: Peter Zijlstra <peterz@infradead.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
	x86@kernel.org, Andy Lutomirski <luto@kernel.org>,
	Linus Torvalds <torvalds@linuxfoundation.org>,
	Stephen Hemminger <stephen@networkplumber.org>,
	Willy Tarreau <w@1wt.eu>, Juergen Gross <jgross@suse.com>,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	"H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [patch V3 00/20] x86/iopl: Prevent user space from using CLI/STI with iopl(3)
Date: Thu, 14 Nov 2019 09:43:45 +0100
Message-ID: <20191114084345.GK4131@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20191113204240.767922595@linutronix.de>

On Wed, Nov 13, 2019 at 09:42:40PM +0100, Thomas Gleixner wrote:

> iopl(level = 3) enables aside of access to all 65536 I/O ports also the
> usage of CLI/STI in user space.
> 
> Disabling interrupts in user space can lead to system lockups and breaks
> assumptions in the kernel that userspace always runs with interrupts
> enabled.
> 
> iopl() is often preferred over ioperm() as it avoids the overhead of
> copying the tasks I/O bitmap to the TSS bitmap on context switch. This
> overhead can be avoided by providing a all zeroes bitmap in the TSS and
> switching the TSS bitmap offset to this permit all IO bitmap. It's
> marginally slower than iopl() which is a one time setup, but prevents the
> usage of CLI/STI in user space.

> ---
>  arch/x86/Kconfig                        |   18 ++
>  arch/x86/entry/common.c                 |    4 
>  arch/x86/include/asm/io_bitmap.h        |   29 ++++
>  arch/x86/include/asm/paravirt.h         |    4 
>  arch/x86/include/asm/paravirt_types.h   |    2 
>  arch/x86/include/asm/pgtable_32_types.h |    2 
>  arch/x86/include/asm/processor.h        |  113 ++++++++++-------
>  arch/x86/include/asm/ptrace.h           |    6 
>  arch/x86/include/asm/switch_to.h        |   10 +
>  arch/x86/include/asm/thread_info.h      |   14 +-
>  arch/x86/include/asm/xen/hypervisor.h   |    2 
>  arch/x86/kernel/cpu/common.c            |  188 ++++++++++++----------------
>  arch/x86/kernel/doublefault.c           |    2 
>  arch/x86/kernel/ioport.c                |  209 +++++++++++++++++++++-----------
>  arch/x86/kernel/paravirt.c              |    2 
>  arch/x86/kernel/process.c               |  200 ++++++++++++++++++++++++------
>  arch/x86/kernel/process_32.c            |   77 -----------
>  arch/x86/kernel/process_64.c            |   86 -------------
>  arch/x86/kernel/ptrace.c                |   12 +
>  arch/x86/kvm/vmx/vmx.c                  |    8 -
>  arch/x86/mm/cpu_entry_area.c            |    8 +
>  arch/x86/xen/enlighten_pv.c             |   10 -
>  tools/testing/selftests/x86/ioperm.c    |   16 ++
>  tools/testing/selftests/x86/iopl.c      |  129 ++++++++++++++++++-
>  24 files changed, 674 insertions(+), 477 deletions(-)


Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>

      parent reply index

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-13 20:42 Thomas Gleixner
2019-11-13 20:42 ` [patch V3 01/20] x86/ptrace: Prevent truncation of bitmap size Thomas Gleixner
2019-11-15 21:12   ` [tip: x86/iopl] " tip-bot2 for Thomas Gleixner
2019-11-13 20:42 ` [patch V3 02/20] x86/process: Unify copy_thread_tls() Thomas Gleixner
2019-11-13 21:10   ` Linus Torvalds
2019-11-13 21:41     ` Thomas Gleixner
2019-11-13 22:10       ` Linus Torvalds
2019-11-13 22:33         ` Thomas Gleixner
2019-11-13 21:44     ` Brian Gerst
2019-11-15 21:12   ` [tip: x86/iopl] " tip-bot2 for Thomas Gleixner
2019-11-13 20:42 ` [patch V3 03/20] x86/cpu: Unify cpu_init() Thomas Gleixner
2019-11-15 21:12   ` [tip: x86/iopl] " tip-bot2 for Thomas Gleixner
2019-11-13 20:42 ` [patch V3 04/20] x86/tss: Fix and move VMX BUILD_BUG_ON() Thomas Gleixner
2019-11-15 21:12   ` [tip: x86/iopl] " tip-bot2 for Thomas Gleixner
2019-11-13 20:42 ` [patch V3 05/20] x86/iopl: Cleanup include maze Thomas Gleixner
2019-11-15 21:12   ` [tip: x86/iopl] " tip-bot2 for Thomas Gleixner
2019-11-13 20:42 ` [patch V3 06/20] x86/ioperm: Simplify first ioperm() invocation logic Thomas Gleixner
2019-11-15 21:12   ` [tip: x86/iopl] " tip-bot2 for Thomas Gleixner
2019-11-13 20:42 ` [patch V3 07/20] x86/ioperm: Avoid bitmap allocation if no permissions are set Thomas Gleixner
2019-11-15 21:12   ` [tip: x86/iopl] " tip-bot2 for Thomas Gleixner
2019-11-13 20:42 ` [patch V3 08/20] x86/io: Speedup schedule out of I/O bitmap user Thomas Gleixner
2019-11-15 21:12   ` [tip: x86/iopl] " tip-bot2 for Thomas Gleixner
2019-11-13 20:42 ` [patch V3 09/20] x86/tss: Move I/O bitmap data into a seperate struct Thomas Gleixner
2019-11-15 21:12   ` [tip: x86/iopl] " tip-bot2 for Thomas Gleixner
2019-11-13 20:42 ` [patch V3 10/20] x86/ioperm: Move iobitmap data into a struct Thomas Gleixner
2019-11-15 21:12   ` [tip: x86/iopl] " tip-bot2 for Thomas Gleixner
2019-11-13 20:42 ` [patch V3 11/20] x86/ioperm: Add bitmap sequence number Thomas Gleixner
2019-11-15 21:12   ` [tip: x86/iopl] " tip-bot2 for Thomas Gleixner
2019-11-13 20:42 ` [patch V3 12/20] x86/ioperm: Move TSS bitmap update to exit to user work Thomas Gleixner
2019-11-13 21:19   ` Linus Torvalds
2019-11-13 21:21     ` Linus Torvalds
2019-11-13 21:44       ` Thomas Gleixner
2019-11-15 21:12   ` [tip: x86/iopl] " tip-bot2 for Thomas Gleixner
2019-11-13 20:42 ` [patch V3 13/20] x86/ioperm: Remove bitmap if all permissions dropped Thomas Gleixner
2019-11-15 21:12   ` [tip: x86/iopl] " tip-bot2 for Thomas Gleixner
2019-11-13 20:42 ` [patch V3 14/20] x86/ioperm: Share I/O bitmap if identical Thomas Gleixner
2019-11-15 21:12   ` [tip: x86/iopl] " tip-bot2 for Thomas Gleixner
2019-11-13 20:42 ` [patch V3 15/20] selftests/x86/ioperm: Extend testing so the shared bitmap is exercised Thomas Gleixner
2019-11-15 21:12   ` [tip: x86/iopl] " tip-bot2 for Thomas Gleixner
2019-11-13 20:42 ` [patch V3 16/20] x86/iopl: Fixup misleading comment Thomas Gleixner
2019-11-15 21:12   ` [tip: x86/iopl] " tip-bot2 for Thomas Gleixner
2019-11-13 20:42 ` [patch V3 17/20] x86/iopl: Restrict iopl() permission scope Thomas Gleixner
2019-11-14 18:13   ` Borislav Petkov
2019-11-14 18:39     ` Thomas Gleixner
2019-11-15 21:12   ` [tip: x86/iopl] " tip-bot2 for Thomas Gleixner
2019-11-13 20:42 ` [patch V3 18/20] x86/iopl: Remove legacy IOPL option Thomas Gleixner
2019-11-15 21:12   ` [tip: x86/iopl] " tip-bot2 for Thomas Gleixner
2019-11-13 20:42 ` [patch V3 19/20] x86/ioperm: Extend IOPL config to control ioperm() as well Thomas Gleixner
2019-11-15 21:12   ` [tip: x86/iopl] " tip-bot2 for Thomas Gleixner
2019-11-13 20:43 ` [patch V3 20/20] selftests/x86/iopl: Extend test to cover IOPL emulation Thomas Gleixner
2019-11-15 21:12   ` [tip: x86/iopl] " tip-bot2 for Thomas Gleixner
2019-11-14  8:43 ` Peter Zijlstra [this message]

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