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From: Borislav Petkov <bp@kernel.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>, Peter Anvin <hpa@zytor.com>,
	the arch/x86 maintainers <x86@kernel.org>,
	One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>,
	Borislav Petkov <bp@alien8.de>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Brian Gerst <brgerst@gmail.com>,
	Matthew Whitehead <tedheadster@gmail.com>,
	Henrique de Moraes Holschuh <hmh@hmh.eng.br>,
	Peter Zijlstra <peterz@infradead.org>,
	Andrew Cooper <andrew.cooper3@citrix.com>
Subject: Re: [PATCH v2 5/6] x86/xen: Add a Xen-specific sync_core() implementation
Date: Fri, 2 Dec 2016 19:50:08 +0100	[thread overview]
Message-ID: <20161202185008.tdziqrzi4a3axord@pd.tnic> (raw)
In-Reply-To: <CA+55aFyHptQ3=gjXA_LGGkvOgsRB9FBXvCT56fG4UqcFV4wFsA@mail.gmail.com>

On Fri, Dec 02, 2016 at 10:27:29AM -0800, Linus Torvalds wrote:
> That is, of course, assuming that there  is no really subtle reason
> why that stupid sync_core() is there.

Right, we can try to do something like invalidate_icache() or so in
there with the JMP so that the BSP refetches modified code and see where
it gets us.

The good thing is, the early patching paths run before SMP is
up but from looking at load_module(), for example, which does
post_relocation()->module_finalize()->apply_alternatives(), this can
happen late.

Now there I'd like to avoid other cores walking into that address being
patched. Or are we "safe" there in the sense that load_module() happens
on one CPU only sequentially? (I haven't looked at that code to see
what's going on there, actually).

-- 
Regards/Gruss,
    Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.

  reply	other threads:[~2016-12-02 18:50 UTC|newest]

Thread overview: 65+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-11-30 20:34 [PATCH 0/4] CPUID-less CPU fixes and improvements Andy Lutomirski
2016-11-30 20:34 ` [PATCH 1/4] x86/asm/32: Make sync_core() handle missing CPUID on all 32-bit kernels Andy Lutomirski
2016-11-30 20:34 ` [PATCH 2/4] Revert "x86/boot: Fail the boot if !M486 and CPUID is missing" Andy Lutomirski
2016-12-01  5:53   ` Peter Zijlstra
2016-12-01  9:02     ` Borislav Petkov
2016-12-01 10:07       ` Thomas Gleixner
2016-12-01 11:15         ` [PATCH] x86/CPU: Add X86_FEATURE_CPUID Borislav Petkov
2016-12-01 17:00           ` Andy Lutomirski
2016-12-02  0:33       ` [PATCH 2/4] Revert "x86/boot: Fail the boot if !M486 and CPUID is missing" Andy Lutomirski
2016-12-01 17:00     ` Andy Lutomirski
2016-11-30 20:34 ` [PATCH 3/4] x86/microcode/intel: Replace sync_core() with cpuid_eax(1) Andy Lutomirski
2016-12-01  9:11   ` Borislav Petkov
2016-11-30 20:34 ` [PATCH 4/4] x86/asm: Change sync_core() to use MOV to CR2 to serialize Andy Lutomirski
2016-12-01  9:22   ` Borislav Petkov
2016-12-01 17:08     ` Andy Lutomirski
2016-12-01 17:46       ` Andrew Cooper
2016-12-02  7:34     ` Ingo Molnar
2016-12-02  0:34 ` [PATCH v2 0/6] CPUID-less CPU/sync_core fixes and improvements Andy Lutomirski
2016-12-02  0:34   ` [PATCH v2 1/6] x86/asm/32: Make sync_core() handle missing CPUID on all 32-bit kernels Andy Lutomirski
2016-12-02  0:34   ` [PATCH v2 2/6] Revert "x86/boot: Fail the boot if !M486 and CPUID is missing" Andy Lutomirski
2016-12-02  0:34   ` [PATCH v2 3/6] x86/microcode/intel: Replace sync_core() with cpuid_eax(1) Andy Lutomirski
2016-12-02  0:35   ` [PATCH v2 4/6] x86/paravirt: Make sync_core() be a paravirt op Andy Lutomirski
2016-12-02  0:35   ` [PATCH v2 5/6] x86/xen: Add a Xen-specific sync_core() implementation Andy Lutomirski
2016-12-02 11:44     ` Andrew Cooper
2016-12-02 11:44     ` Andrew Cooper
2016-12-02 17:07       ` Andy Lutomirski
2016-12-02 17:07       ` Andy Lutomirski
2016-12-02 17:16         ` Andrew Cooper
2016-12-02 17:16         ` Andrew Cooper
2016-12-02 17:23           ` Andy Lutomirski
2016-12-02 17:26             ` Andrew Cooper
2016-12-02 17:26             ` Andrew Cooper
2016-12-02 17:23           ` Andy Lutomirski
2016-12-02 18:50       ` Boris Ostrovsky
2016-12-02 18:50       ` Boris Ostrovsky
2016-12-02 19:34         ` Andy Lutomirski
2016-12-02 19:34         ` Andy Lutomirski
2016-12-02 20:09       ` Boris Ostrovsky
2016-12-02 20:09         ` Boris Ostrovsky
2016-12-02 17:32     ` Linus Torvalds
2016-12-02 17:38       ` Andy Lutomirski
2016-12-02 17:53         ` Linus Torvalds
2016-12-02 18:03         ` Borislav Petkov
2016-12-02 18:27           ` Linus Torvalds
2016-12-02 18:50             ` Borislav Petkov [this message]
2016-12-02 19:03               ` Linus Torvalds
2016-12-02 19:20                 ` Borislav Petkov
2016-12-02 19:24                   ` Linus Torvalds
2016-12-02 19:28                     ` Borislav Petkov
2016-12-03 15:02                       ` [PATCH] x86/alternatives: Do not use sync_core() to serialize I$ Borislav Petkov
2016-12-03 17:05                         ` Andy Lutomirski
2016-12-20  7:58                         ` [tip:x86/urgent] " tip-bot for Borislav Petkov
2016-12-20  9:35                         ` tip-bot for Borislav Petkov
2016-12-02 19:30                     ` [PATCH v2 5/6] x86/xen: Add a Xen-specific sync_core() implementation Andy Lutomirski
2016-12-02 19:35                       ` Linus Torvalds
2016-12-02 20:41                         ` Andy Lutomirski
2016-12-02 21:10                           ` Linus Torvalds
2016-12-02 22:55                             ` Andy Lutomirski
2016-12-02 23:09                               ` Linus Torvalds
2016-12-02 19:23                 ` Andy Lutomirski
2016-12-02 19:30                   ` Borislav Petkov
2016-12-03 12:44         ` Borislav Petkov
2016-12-02  0:35   ` [PATCH v2 6/6] x86/asm: Change sync_core() to use MOV to CR2 to serialize Andy Lutomirski
2016-12-02  0:36 ` [PATCH 0/4] CPUID-less CPU fixes and improvements Andy Lutomirski
2016-12-02 10:17   ` Ingo Molnar

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