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From: Borislav Petkov <bp@alien8.de>
To: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: gshan@redhat.com, Anson.Huang@nxp.com, geert+renesas@glider.be,
	catalin.marinas@arm.com, masahiroy@kernel.org,
	linux-kernel@vger.kernel.org, michael@walle.cc, krzk@kernel.org,
	bjorn.andersson@linaro.org, vkoul@kernel.org, olof@lixom.net,
	shawnguo@kernel.org, vincenzo.frascino@arm.com, will@kernel.org,
	ardb@kernel.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 0/3] arm64:msr: Add MSR driver
Date: Mon, 30 Nov 2020 20:03:31 +0100	[thread overview]
Message-ID: <20201130190331.GI6019@zn.tnic> (raw)
In-Reply-To: <20201130174833.41315-1-rongwei.wang@linux.alibaba.com>

On Tue, Dec 01, 2020 at 01:48:30AM +0800, Rongwei Wang wrote:
> MSR ARM driver aims to provide interfacs for user to read or write
> data to all system registers.

Just a warranty from x86 land: if I were an ARM arch maintainer, I would
never never *ever* take such driver exposing naked hw registers to
userspace.

We have been fighting with this on x86 for years:

a7e1f67ed29f ("x86/msr: Filter MSR writes")

with userspace tools poking at random MSRs. Read the commit message
for what can happen. And taking that thing is like opening a huge
can'o'worms that can't be closed anymore.

Currently, we're trying to move userspace tools to proper sysfs
interfaces but it is a huuuge pain. It is a lot easier to have people
define proper interfaces from the get-go where the kernel can control
and synchronize access.

HTH.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

WARNING: multiple messages have this Message-ID (diff)
From: Borislav Petkov <bp@alien8.de>
To: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: catalin.marinas@arm.com, will@kernel.org,
	bjorn.andersson@linaro.org, shawnguo@kernel.org,
	vkoul@kernel.org, geert+renesas@glider.be, Anson.Huang@nxp.com,
	michael@walle.cc, krzk@kernel.org, olof@lixom.net,
	vincenzo.frascino@arm.com, ardb@kernel.org, masahiroy@kernel.org,
	gshan@redhat.com, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/3] arm64:msr: Add MSR driver
Date: Mon, 30 Nov 2020 20:03:31 +0100	[thread overview]
Message-ID: <20201130190331.GI6019@zn.tnic> (raw)
In-Reply-To: <20201130174833.41315-1-rongwei.wang@linux.alibaba.com>

On Tue, Dec 01, 2020 at 01:48:30AM +0800, Rongwei Wang wrote:
> MSR ARM driver aims to provide interfacs for user to read or write
> data to all system registers.

Just a warranty from x86 land: if I were an ARM arch maintainer, I would
never never *ever* take such driver exposing naked hw registers to
userspace.

We have been fighting with this on x86 for years:

a7e1f67ed29f ("x86/msr: Filter MSR writes")

with userspace tools poking at random MSRs. Read the commit message
for what can happen. And taking that thing is like opening a huge
can'o'worms that can't be closed anymore.

Currently, we're trying to move userspace tools to proper sysfs
interfaces but it is a huuuge pain. It is a lot easier to have people
define proper interfaces from the get-go where the kernel can control
and synchronize access.

HTH.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

  parent reply	other threads:[~2020-11-30 19:04 UTC|newest]

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-30 17:48 [PATCH 0/3] arm64:msr: Add MSR driver Rongwei Wang
2020-11-30 17:48 ` Rongwei Wang
2020-11-30 17:48 ` [PATCH 1/3] arm64:insn: Export symbols for MSR ARM driver Rongwei Wang
2020-11-30 17:48   ` Rongwei Wang
2020-11-30 17:48 ` [PATCH 2/3] arm64:msr: Introduce " Rongwei Wang
2020-11-30 17:48   ` Rongwei Wang
2020-11-30 23:14   ` kernel test robot
2020-11-30 17:48 ` [PATCH 3/3] arm64:msr: Enable " Rongwei Wang
2020-11-30 17:48   ` Rongwei Wang
2020-11-30 17:57 ` [PATCH 0/3] arm64:msr: Add MSR driver Will Deacon
2020-11-30 17:57   ` Will Deacon
2020-12-01  2:55   ` wangrongwei
2020-12-01  2:55     ` wangrongwei
2020-12-01  5:44   ` wangrongwei
2020-12-01  5:44     ` wangrongwei
2020-11-30 18:05 ` Marc Zyngier
2020-11-30 18:05   ` Marc Zyngier
2020-11-30 18:20   ` Randy Dunlap
2020-11-30 18:20     ` Randy Dunlap
2020-12-01  3:09   ` wangrongwei
2020-12-01  3:09     ` wangrongwei
2020-12-01  8:12     ` Marc Zyngier
2020-12-01  8:12       ` Marc Zyngier
2020-12-01 14:25       ` wangrongwei
2020-12-01 14:25         ` wangrongwei
2020-12-01 15:37         ` Marc Zyngier
2020-12-01 15:37           ` Marc Zyngier
2020-12-03  5:45           ` Rongwei Wang
2020-12-03  5:45             ` Rongwei Wang
2020-12-03  8:35             ` Marc Zyngier
2020-12-03  8:35               ` Marc Zyngier
2020-12-03 11:25               ` Rongwei Wang
2020-12-03 11:25                 ` Rongwei Wang
2020-12-03 11:45                 ` Marc Zyngier
2020-12-03 11:45                   ` Marc Zyngier
2020-12-03 12:22                   ` Rongwei Wang
2020-12-03 12:22                     ` Rongwei Wang
2020-12-03 11:50                 ` Mark Rutland
2020-12-03 11:50                   ` Mark Rutland
2020-11-30 19:03 ` Borislav Petkov [this message]
2020-11-30 19:03   ` Borislav Petkov
2020-12-01  3:44   ` wangrongwei
2020-12-01  3:44     ` wangrongwei
2020-12-01 11:26     ` Borislav Petkov
2020-12-01 11:26       ` Borislav Petkov
2020-12-01 14:33       ` wangrongwei
2020-12-01 14:33         ` wangrongwei
2020-12-01 14:54         ` Borislav Petkov
2020-12-01 14:54           ` Borislav Petkov
2020-12-01 15:17           ` Rongwei Wang
2020-12-01 15:17             ` Rongwei Wang
2020-12-01 15:25             ` Borislav Petkov
2020-12-01 15:25               ` Borislav Petkov
2020-12-03  2:09               ` Rongwei Wang
2020-12-03  2:09                 ` Rongwei Wang
2020-12-01 15:26             ` Ard Biesheuvel
2020-12-01 15:26               ` Ard Biesheuvel

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