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From: David Woodhouse <dwmw2@infradead.org>
To: Paolo Bonzini <pbonzini@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	 Thomas Gleixner <tglx@linutronix.de>,
	Josh Poimboeuf <jpoimboe@redhat.com>
Cc: linux-kernel@vger.kernel.org, Dave Hansen <dave.hansen@intel.com>,
	Ashok Raj <ashok.raj@intel.com>,
	Tim Chen <tim.c.chen@linux.intel.com>,
	Andy Lutomirski <luto@kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Greg KH <gregkh@linuxfoundation.org>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Andi Kleen <ak@linux.intel.com>,
	Arjan Van De Ven <arjan.van.de.ven@intel.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Jun Nakajima <jun.nakajima@intel.com>,
	Asit Mallick <asit.k.mallick@intel.com>,
	Jason Baron <jbaron@akamai.com>
Subject: Re: [PATCH 34/35] x86/kvm: Add IBPB support
Date: Fri, 19 Jan 2018 17:08:13 +0100	[thread overview]
Message-ID: <1516378093.5087.30.camel@infradead.org> (raw)
In-Reply-To: <baa93988-c592-c058-0b22-be3c1bf416c0@redhat.com>

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On Fri, 2018-01-19 at 16:25 +0100, Paolo Bonzini wrote:
> Without retpolines, KVM userspace is not protected from the guest
> poisoning the BTB, because there is no IBRS-barrier on the vmexit
> path.
> So there are two more IBPBs that are needed if retpolines are
> enabled:
> 
> 1) in kvm_sched_out
> 
> 2) at the end of vcpu_run

Hm, yes. That does seem reasonable. Can we make it conditional so it
only happens *if* we end up back in userspace, and not for a VM-
>kernel->VM transition?

And can I have a patch against
http://git.infradead.org/users/dwmw2/linux-retpoline.git/shortlog/refs/heads/ibpb-upstream
please (see the XX in that top commit too).

I'm still putting that together, and the IBRS bits on top; getting on
an airplane to spend some more quality time with it now...

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  reply	other threads:[~2018-01-19 16:08 UTC|newest]

Thread overview: 65+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-18 13:48 [PATCH 00/35] jump_label, objtool, IBRS and IBPB Peter Zijlstra, Peter Zijlstra
2018-01-18 13:48 ` [PATCH 01/35] jump_label: Add branch hints to static_branch_{un,}likely() Peter Zijlstra, Peter Zijlstra
2018-01-18 13:48 ` [PATCH 02/35] sched: Optimize ttwu_stat() Peter Zijlstra, Peter Zijlstra
2018-01-18 13:48 ` [PATCH 03/35] x86: Reindent _static_cpu_has Peter Zijlstra, Peter Zijlstra
2018-01-18 13:48 ` [PATCH 04/35] x86: Update _static_cpu_has to use all named variables Peter Zijlstra, Peter Zijlstra
2018-01-18 13:48 ` [PATCH 05/35] x86: Add a type field to alt_instr Peter Zijlstra, Peter Zijlstra
2018-01-18 13:48 ` [PATCH 06/35] objtool: Implement base jump_assert support Peter Zijlstra, Peter Zijlstra
2018-01-18 13:48 ` [PATCH 07/35] x86: Annotate static_cpu_has alternative Peter Zijlstra, Peter Zijlstra
2018-01-18 13:48 ` [PATCH 08/35] objtool: Implement jump_assert for _static_cpu_has() Peter Zijlstra, Peter Zijlstra
2018-01-18 13:48 ` [PATCH 09/35] objtool: Introduce special_type Peter Zijlstra, Peter Zijlstra
2018-01-18 13:48 ` [PATCH 10/35] x86/jump_label: Implement arch_static_assert() Peter Zijlstra, Peter Zijlstra
2018-01-18 13:48 ` [PATCH 11/35] objtool: Add retpoline validation Peter Zijlstra, Peter Zijlstra
2018-01-18 13:48 ` [PATCH 12/35] x86/paravirt: Annotate indirect calls Peter Zijlstra, Peter Zijlstra
2018-01-18 13:48 ` [PATCH 13/35] x86,nospec: Annotate indirect calls/jumps Peter Zijlstra, Peter Zijlstra
2018-01-18 13:48 ` [PATCH 14/35] x86: Annotate indirect jump in head_64.S Peter Zijlstra, Peter Zijlstra
2018-01-18 13:48 ` [PATCH 15/35] objtool: More complex static jump implementation Peter Zijlstra, Peter Zijlstra
2018-01-18 13:48 ` [PATCH 16/35] objtool: Use existing global variables for options Peter Zijlstra, Peter Zijlstra
2018-01-18 13:48 ` [PATCH 17/35] objtool: Even more complex static block checks Peter Zijlstra, Peter Zijlstra
2018-01-18 13:48 ` [PATCH 18/35] objtool: Another static block fail Peter Zijlstra, Peter Zijlstra
2018-01-19 16:42   ` Peter Zijlstra
2018-01-29 18:01     ` Josh Poimboeuf
2018-01-29 18:24       ` Peter Zijlstra
2018-01-18 13:48 ` [PATCH 19/35] objtool: Skip static assert when KCOV/KASAN Peter Zijlstra, Peter Zijlstra
2018-01-18 13:48 ` [PATCH 20/35] x86: Force asm-goto Peter Zijlstra, Peter Zijlstra
2018-01-18 16:25   ` David Woodhouse
2018-01-18 13:48 ` [PATCH 21/35] x86: Remove FAST_FEATURE_TESTS Peter Zijlstra, Peter Zijlstra
2018-01-18 13:48 ` [PATCH 22/35] x86/cpufeatures: Detect Speculation control feature Peter Zijlstra, Peter Zijlstra
2018-01-18 13:48 ` [PATCH 23/35] x86/speculation: Add basic speculation control code Peter Zijlstra, Peter Zijlstra
2018-01-18 16:37   ` Josh Poimboeuf
2018-01-18 17:08     ` Dave Hansen
2018-01-18 17:12       ` Paolo Bonzini
2018-01-18 18:24         ` Josh Poimboeuf
2018-01-18 19:08           ` Andrea Arcangeli
2018-01-18 23:25             ` Andy Lutomirski
2018-01-18 23:35               ` Andrew Cooper
2018-01-19  1:41               ` Andrea Arcangeli
2018-01-19  4:10                 ` Andy Lutomirski
2018-01-19  4:15                   ` Van De Ven, Arjan
2018-01-19 15:47                     ` Andrea Arcangeli
2018-01-18 13:48 ` [PATCH 24/35] x86/msr: Move native_*msr macros out of microcode.h Peter Zijlstra, Peter Zijlstra
2018-01-18 13:48 ` [PATCH 25/35] x86/speculation: Add inlines to control Indirect Branch Speculation Peter Zijlstra, Peter Zijlstra
2018-01-18 13:48 ` [PATCH 26/35] x86/enter: Create macros to stop/restart " Peter Zijlstra, Peter Zijlstra
2018-01-18 19:44   ` Tim Chen
2018-01-18 13:48 ` [PATCH 27/35] x86/enter: Use IBRS on syscall and interrupts Peter Zijlstra, Peter Zijlstra
2018-01-18 13:48 ` [PATCH 28/35] x86/idle: Control Indirect Branch Speculation in idle Peter Zijlstra, Peter Zijlstra
2018-01-18 19:52   ` Andrew Cooper
2018-01-18 13:48 ` [PATCH 29/35] x86/speculation: Add IPBP support Peter Zijlstra, Peter Zijlstra
2018-01-18 16:22   ` Josh Poimboeuf
2018-01-18 18:31   ` Borislav Petkov
2018-01-18 18:35     ` Josh Poimboeuf
2018-01-18 18:46       ` Borislav Petkov
2018-01-18 13:48 ` [PATCH 30/35] x86/speculation: Use Indirect Branch Prediction Barrier in context switch Peter Zijlstra, Peter Zijlstra
2018-01-19  0:38   ` Tim Chen
2018-01-19  4:03     ` Kevin Easton
2018-01-19 20:26       ` Tim Chen
2018-01-18 13:48 ` [PATCH 31/35] x86/ibrs: Add new helper macros to save/restore MSR_IA32_SPEC_CTRL Peter Zijlstra, Peter Zijlstra
2018-01-18 13:48 ` [PATCH 32/35] x86/vmx: Direct access to MSR_IA32_SPEC_CTRL Peter Zijlstra, Peter Zijlstra
2018-01-18 13:48 ` [PATCH 33/35] x86/svm: " Peter Zijlstra, Peter Zijlstra
2018-01-18 13:48 ` [PATCH 34/35] x86/kvm: Add IBPB support Peter Zijlstra, Peter Zijlstra
2018-01-18 15:32   ` Paolo Bonzini
2018-01-19 15:25     ` Paolo Bonzini
2018-01-19 16:08       ` David Woodhouse [this message]
2018-01-19 16:27         ` Andy Lutomirski
2018-01-19 16:48         ` Paolo Bonzini
2018-01-18 13:48 ` [PATCH 35/35] x86/nospec: Add static assertions Peter Zijlstra, Peter Zijlstra

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