From: Dave Hansen <dave.hansen@intel.com>
To: Arnd Bergmann <arnd@arndb.de>,
Dan Williams <dan.j.williams@intel.com>,
Dave Hansen <dave.hansen@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Ingo Molnar <mingo@kernel.org>, Kees Cook <kees@kernel.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Naveen N Rao <naveen@kernel.org>,
Nikolay Borisov <nik.borisov@suse.com>,
stable@vger.kernel.org, Suzuki K Poulose <suzuki.poulose@arm.com>,
Vishal Annapurve <vannapurve@google.com>,
x86@kernel.org, linux-coco@lists.linux.dev
Subject: Re: [PATCH v5] x86/devmem: Drop /dev/mem access for confidential guests
Date: Thu, 1 May 2025 13:18:04 -0700 [thread overview]
Message-ID: <61b4cbf2-efdb-4023-9e2a-1185ee308d6e@intel.com> (raw)
In-Reply-To: <5f80ae16-8d41-4a68-b978-c1bb60fce3f1@app.fastmail.com>
On 5/1/25 13:01, Arnd Bergmann wrote:
> If there is software that still relies on those hacks, it's
> probably very old, and more likely to be on 32-bit systems.
> There are many references to /dev/mem in Debian codesearch [1],
> but it's usually related to pre-PCIe graphics (svgalib, XFree86,
> uvesafb/v86), or it's memory-only accesses that rely on
> !CONFIG_STRICT_DEVMEM to read kernel structures.
>
> Arnd
>
> [1] https://codesearch.debian.net/search?q=%2Fdev%2Fmem&literal=1&perpkg=1
I did basically the same exercise a week or two ago. I really didn't see
any examples that concerned me. I completely agree that it looked very
much limited to old, crusty code that either doesn't matter at _all_ or
code that falls back to newer mechanisms on modern
CONFIG_STRICT_DEVMEM=y systems.
prev parent reply other threads:[~2025-05-01 20:18 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-04-30 2:46 [PATCH v5] Restrict devmem for confidential VMs Dan Williams
2025-04-30 2:46 ` [PATCH v5] x86/devmem: Remove duplicate range_is_allowed() definition Dan Williams
2025-04-30 7:19 ` Greg Kroah-Hartman
2025-04-30 2:46 ` [PATCH v5] x86/devmem: Drop /dev/mem access for confidential guests Dan Williams
2025-04-30 7:19 ` Greg Kroah-Hartman
2025-04-30 23:03 ` Dan Williams
2025-04-30 17:31 ` Arnd Bergmann
2025-05-01 0:56 ` Dan Williams
2025-05-01 8:12 ` Arnd Bergmann
2025-05-01 20:01 ` Arnd Bergmann
2025-05-01 20:18 ` Dave Hansen [this message]
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