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From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Masami Hiramatsu <mhiramat@kernel.org>, Ingo Molnar <mingo@kernel.org>
Cc: Juergen Gross <jgross@suse.com>,
	Stefano Stabellini <sstabellini@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Randy Dunlap <rdunlap@infradead.org>, <x86@kernel.org>,
	<linux-kernel@vger.kernel.org>, Borislav Petkov <bp@alien8.de>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	<xen-devel@lists.xenproject.org>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>
Subject: Re: [Xen-devel] [PATCH -tip 0/2] x86: Prohibit kprobes on XEN_EMULATE_PREFIX
Date: Wed, 4 Sep 2019 12:54:55 +0100	[thread overview]
Message-ID: <ad6431be-c86e-5ed5-518a-d1e9d1959e80@citrix.com> (raw)
In-Reply-To: <156759754770.24473.11832897710080799131.stgit@devnote2>

On 04/09/2019 12:45, Masami Hiramatsu wrote:
> Hi,
>
> These patches allow x86 instruction decoder to decode
> xen-cpuid which has XEN_EMULATE_PREFIX, and prohibit
> kprobes to probe on it.
>
> Josh reported that the objtool can not decode such special
> prefixed instructions, and I found that we also have to
> prohibit kprobes to probe on such instruction.
>
> This series can be applied on -tip master branch which
> has merged Josh's objtool/perf sharing common x86 insn
> decoder series.

The paravirtualised xen-cpuid is were you'll see it most in a regular
kernel, but be aware that it is also used for testing purposes in other
circumstances, and there is an equivalent KVM prefix which is used for
KVM testing.

It might be better to generalise the decode support to "virtualisation
escape prefix" or something slightly more generic.

~Andrew

WARNING: multiple messages have this Message-ID (diff)
From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Masami Hiramatsu <mhiramat@kernel.org>, Ingo Molnar <mingo@kernel.org>
Cc: Juergen Gross <jgross@suse.com>,
	Stefano Stabellini <sstabellini@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	x86@kernel.org, linux-kernel@vger.kernel.org,
	Borislav Petkov <bp@alien8.de>,
	Randy Dunlap <rdunlap@infradead.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	xen-devel@lists.xenproject.org,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>
Subject: Re: [Xen-devel] [PATCH -tip 0/2] x86: Prohibit kprobes on XEN_EMULATE_PREFIX
Date: Wed, 4 Sep 2019 12:54:55 +0100	[thread overview]
Message-ID: <ad6431be-c86e-5ed5-518a-d1e9d1959e80@citrix.com> (raw)
In-Reply-To: <156759754770.24473.11832897710080799131.stgit@devnote2>

On 04/09/2019 12:45, Masami Hiramatsu wrote:
> Hi,
>
> These patches allow x86 instruction decoder to decode
> xen-cpuid which has XEN_EMULATE_PREFIX, and prohibit
> kprobes to probe on it.
>
> Josh reported that the objtool can not decode such special
> prefixed instructions, and I found that we also have to
> prohibit kprobes to probe on such instruction.
>
> This series can be applied on -tip master branch which
> has merged Josh's objtool/perf sharing common x86 insn
> decoder series.

The paravirtualised xen-cpuid is were you'll see it most in a regular
kernel, but be aware that it is also used for testing purposes in other
circumstances, and there is an equivalent KVM prefix which is used for
KVM testing.

It might be better to generalise the decode support to "virtualisation
escape prefix" or something slightly more generic.

~Andrew

_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel

  parent reply	other threads:[~2019-09-04 11:55 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-04 11:45 [PATCH -tip 0/2] x86: Prohibit kprobes on XEN_EMULATE_PREFIX Masami Hiramatsu
2019-09-04 11:45 ` [Xen-devel] " Masami Hiramatsu
2019-09-04 11:45 ` [PATCH -tip 1/2] x86: xen: insn: Decode XEN_EMULATE_PREFIX correctly Masami Hiramatsu
2019-09-04 11:45   ` [Xen-devel] " Masami Hiramatsu
2019-09-04 11:46 ` [PATCH -tip 2/2] x86: kprobes: Prohibit probing on instruction which has Xen prefix Masami Hiramatsu
2019-09-04 11:46   ` [Xen-devel] " Masami Hiramatsu
2019-09-04 11:54 ` Andrew Cooper [this message]
2019-09-04 11:54   ` [Xen-devel] [PATCH -tip 0/2] x86: Prohibit kprobes on XEN_EMULATE_PREFIX Andrew Cooper
2019-09-05  1:49   ` Masami Hiramatsu
2019-09-05  1:49     ` Masami Hiramatsu
2019-09-05  7:54     ` Andrew Cooper
2019-09-05  7:54       ` Andrew Cooper
2019-09-05  8:26       ` Peter Zijlstra
2019-09-05  8:26         ` Peter Zijlstra
2019-09-05  8:53         ` Andrew Cooper
2019-09-05  8:53           ` Andrew Cooper
2019-09-05  9:26           ` Peter Zijlstra
2019-09-05  9:26             ` Peter Zijlstra
2019-09-05  9:38             ` Andrew Cooper
2019-09-05  9:38               ` Andrew Cooper
2019-09-05 12:49           ` [OT] " Masami Hiramatsu
2019-09-05 12:49             ` [Xen-devel] [OT] " Masami Hiramatsu
2019-09-05 11:32       ` [Xen-devel] " Masami Hiramatsu
2019-09-05 11:32         ` Masami Hiramatsu
2019-09-05 13:09         ` Masami Hiramatsu
2019-09-05 13:09           ` Masami Hiramatsu
2019-09-05 13:31           ` Andrew Cooper
2019-09-05 13:31             ` Andrew Cooper
2019-09-05 16:12             ` Masami Hiramatsu
2019-09-05 16:12               ` Masami Hiramatsu
2019-09-04 12:02 ` Peter Zijlstra
2019-09-04 12:02   ` [Xen-devel] " Peter Zijlstra

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