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From: Peter Zijlstra <peterz@infradead.org>
To: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
	David.Kaplan@amd.com, Andrew.Cooper3@citrix.com,
	gregkh@linuxfoundation.org
Subject: Re: [RFC][PATCH 07/17] x86/cpu/kvm: Provide UNTRAIN_RET_VM
Date: Wed, 9 Aug 2023 17:10:47 +0200	[thread overview]
Message-ID: <20230809151047.GT212435@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20230809143000.tus4hqdaobk667eo@treble>

On Wed, Aug 09, 2023 at 10:30:00AM -0400, Josh Poimboeuf wrote:
> On Wed, Aug 09, 2023 at 04:06:44PM +0200, Peter Zijlstra wrote:
> > On Wed, Aug 09, 2023 at 09:50:04AM -0400, Josh Poimboeuf wrote:
> > > On Wed, Aug 09, 2023 at 09:12:25AM +0200, Peter Zijlstra wrote:
> > > > With the difference being that UNTRAIN_RET_VM uses
> > > > X86_FEATURE_IBPB_ON_VMEXIT instead of X86_FEATURE_ENTRY_IBPB.
> > > > 
> > > > This cures VMEXIT doing potentially unret+IBPB or double IBPB.
> > > > 
> > > > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> > > > ---
> > > >  arch/x86/include/asm/nospec-branch.h |   11 +++++++++++
> > > >  arch/x86/kernel/cpu/bugs.c           |   17 ++++++++++++++++-
> > > >  arch/x86/kvm/svm/vmenter.S           |    7 ++-----
> > > >  3 files changed, 29 insertions(+), 6 deletions(-)
> > > > 
> > > > --- a/arch/x86/include/asm/nospec-branch.h
> > > > +++ b/arch/x86/include/asm/nospec-branch.h
> > > > @@ -299,6 +299,17 @@
> > > >  #endif
> > > >  .endm
> > > >  
> > > > +.macro UNTRAIN_RET_VM
> > > > +#if defined(CONFIG_CPU_UNRET_ENTRY) || defined(CONFIG_CPU_IBPB_ENTRY) || \
> > > > +	defined(CONFIG_CALL_DEPTH_TRACKING) || defined(CONFIG_CPU_SRSO)
> > > 
> > > Maybe can be simplified?
> > > 
> > 
> > See patches 9 and 10 :-)
> 
> Can still be further simplified to CONFIG_RETHUNK?

Hmm, probably, but my brain seems to be giving out. Let me do the whole
dinner and kids to bed thing and I'll look again later.

  reply	other threads:[~2023-08-09 15:11 UTC|newest]

Thread overview: 80+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-08-09  7:12 [RFC][PATCH 00/17] Fix up the recent SRSO patches Peter Zijlstra
2023-08-09  7:12 ` [RFC][PATCH 01/17] x86/alternative: Unconditional custom return thunk Peter Zijlstra
2023-08-09  9:31   ` Nikolay Borisov
2023-08-10 11:37   ` Borislav Petkov
2023-08-09  7:12 ` [RFC][PATCH 02/17] x86/cpu: Clean up SRSO return thunk mess Peter Zijlstra
2023-08-09 15:45   ` Nikolay Borisov
2023-08-10 11:51   ` Borislav Petkov
2023-08-10 12:37     ` Peter Zijlstra
2023-08-10 12:56       ` Borislav Petkov
2023-08-10 13:22         ` Peter Zijlstra
2023-08-11  7:01       ` Peter Zijlstra
2023-08-11 17:00         ` Nick Desaulniers
2023-08-12 11:20           ` Peter Zijlstra
2023-08-09  7:12 ` [RFC][PATCH 03/17] x86/cpu: Make srso_untrain_ret consistent Peter Zijlstra
2023-08-10 12:00   ` Borislav Petkov
2023-08-09  7:12 ` [RFC][PATCH 04/17] objtool/x86: Fix SRSO mess Peter Zijlstra
2023-08-10 12:06   ` Borislav Petkov
2023-08-10 12:48     ` Peter Zijlstra
2023-08-10 12:50       ` Peter Zijlstra
2023-08-10 15:02         ` Borislav Petkov
2023-08-10 15:22           ` Peter Zijlstra
2023-08-09  7:12 ` [RFC][PATCH 05/17] x86/cpu: Cleanup the untrain mess Peter Zijlstra
2023-08-09 12:51   ` Josh Poimboeuf
2023-08-09 13:12     ` Peter Zijlstra
2023-08-09 13:26       ` Peter Zijlstra
2023-08-12 18:30         ` Borislav Petkov
2023-08-09  7:12 ` [RFC][PATCH 06/17] x86/cpu: Add SRSO untrain to retbleed= Peter Zijlstra
2023-08-09 13:42   ` Josh Poimboeuf
2023-08-09 14:06     ` Peter Zijlstra
2023-08-09 14:28       ` Josh Poimboeuf
2023-08-09 15:08         ` Peter Zijlstra
2023-08-09 15:43           ` Josh Poimboeuf
2023-08-09 14:31     ` Andrew.Cooper3
2023-08-09 14:39       ` Josh Poimboeuf
2023-08-10 15:44   ` Borislav Petkov
2023-08-10 16:10     ` Josh Poimboeuf
2023-08-11 10:27       ` Borislav Petkov
2023-08-12 11:32         ` Peter Zijlstra
2023-08-12 12:12           ` Borislav Petkov
2023-08-14 15:45           ` David Laight
2023-08-12 11:24       ` Peter Zijlstra
2023-08-12 12:10         ` Borislav Petkov
2023-08-14 10:56           ` Peter Zijlstra
2023-08-09  7:12 ` [RFC][PATCH 07/17] x86/cpu/kvm: Provide UNTRAIN_RET_VM Peter Zijlstra
2023-08-09 13:50   ` Josh Poimboeuf
2023-08-09 14:06     ` Peter Zijlstra
2023-08-09 14:30       ` Josh Poimboeuf
2023-08-09 15:10         ` Peter Zijlstra [this message]
2023-08-13 10:36   ` Borislav Petkov
2023-08-14 10:35     ` Peter Zijlstra
2023-08-09  7:12 ` [RFC][PATCH 08/17] x86/cpu: Add IBPB on VMEXIT to retbleed= Peter Zijlstra
2023-08-09  7:12 ` [RFC][PATCH 09/17] x86: Remove CONFIG_CPU_SRSO Peter Zijlstra
2023-08-09 13:57   ` Josh Poimboeuf
2023-08-09  7:12 ` [RFC][PATCH 10/17] x86: Remove CPU_IBPB_ENTRY Peter Zijlstra
2023-08-09  7:12 ` [RFC][PATCH 11/17] x86/cpu: Remove all SRSO interface nonsense Peter Zijlstra
2023-08-09 13:10   ` Andrew.Cooper3
2023-08-09 13:36     ` Peter Zijlstra
2023-08-09 14:05   ` Josh Poimboeuf
2023-08-09 14:43     ` Peter Zijlstra
2023-08-09 14:51       ` Josh Poimboeuf
2023-08-09 15:34   ` Josh Poimboeuf
2023-08-09  7:12 ` [RFC][PATCH 12/17] x86/cpu: Rename original retbleed return thunk Peter Zijlstra
2023-08-09 14:20   ` Josh Poimboeuf
2023-08-09 14:22     ` Peter Zijlstra
2023-08-10 11:06       ` Andrew.Cooper3
2023-08-10 13:02         ` Peter Zijlstra
2023-08-13 15:23           ` Andrew.Cooper3
2023-08-14 10:34             ` Peter Zijlstra
2023-08-14 11:31               ` Andrew.Cooper3
2023-08-14 12:06                 ` Peter Zijlstra
2023-08-09  7:12 ` [RFC][PATCH 13/17] objtool/x86: Add arch_is_offset_insn() Peter Zijlstra
2023-08-09  9:56   ` Nikolay Borisov
2023-08-09 14:34   ` Josh Poimboeuf
2023-08-09  7:12 ` [RFC][PATCH 14/17] objtool: Add comments to the arch_is_$foo() magic symbols Peter Zijlstra
2023-08-09  7:12 ` [RFC][PATCH 15/17] x86/cpu: Rename srso_(.*)_alias to srso_alias_\1 Peter Zijlstra
2023-08-09  7:12 ` [RFC][PATCH 16/17] x86/alternatives: Simplify ALTERNATIVE_n() Peter Zijlstra
2023-08-09  7:12 ` [RFC][PATCH 17/17] x86/cpu: Use fancy alternatives to get rid of entry_untrain_ret() Peter Zijlstra
2023-08-09  9:04 ` [RFC][PATCH 00/17] Fix up the recent SRSO patches Nikolay Borisov
2023-08-09 10:04 ` Andrew.Cooper3
2023-08-09 11:58   ` Peter Zijlstra

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