From: Dave Hansen <dave.hansen@intel.com>
To: Dan Williams <dan.j.williams@intel.com>, dave.hansen@linux.intel.com
Cc: x86@kernel.org, Kees Cook <kees@kernel.org>,
Ingo Molnar <mingo@kernel.org>, Naveen N Rao <naveen@kernel.org>,
Vishal Annapurve <vannapurve@google.com>,
Kirill Shutemov <kirill.shutemov@linux.intel.com>,
Nikolay Borisov <nik.borisov@suse.com>,
stable@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-coco@lists.linux.dev
Subject: Re: [PATCH v3 2/2] x86/devmem: Drop /dev/mem access for confidential guests
Date: Thu, 17 Apr 2025 12:33:30 -0700 [thread overview]
Message-ID: <73f393a9-32e4-4f39-9834-249068ca3294@intel.com> (raw)
In-Reply-To: <174491712829.1395340.5054725417641299524.stgit@dwillia2-xfh.jf.intel.com>
On 4/17/25 12:12, Dan Williams wrote:
...
> + /*
> + * Enforce encrypted mapping consistency and avoid unaccepted
> + * memory conflicts, "lockdown" /dev/mem for confidential
> + * guests.
> + */
> + if (IS_ENABLED(CONFIG_STRICT_DEVMEM) &&
> + cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
> + return -EPERM;
> +
A lot of /dev/mem use seems to be poking at random hardware details like
BIOS internals, ACPI tables or hardware devices. Those all have modern
alternatives. So while I worry that this will make some userspace mad, I
have a hard time imagining that it's _relevant_ userspace on a modern
x86 CoCo platform where that userspace isn't buggy already.
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
next prev parent reply other threads:[~2025-04-17 19:33 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-04-17 19:11 [PATCH v3 0/2] Restrict devmem for confidential VMs Dan Williams
2025-04-17 19:12 ` [PATCH v3 1/2] x86/devmem: Remove duplicate range_is_allowed() definition Dan Williams
2025-04-17 19:30 ` Dave Hansen
2025-04-17 19:12 ` [PATCH v3 2/2] x86/devmem: Drop /dev/mem access for confidential guests Dan Williams
2025-04-17 19:33 ` Dave Hansen [this message]
2025-04-17 22:31 ` kernel test robot
2025-04-17 23:24 ` kernel test robot
2025-04-18 20:04 ` [PATCH v4 " Dan Williams
2025-04-22 13:38 ` Nikolay Borisov
2025-04-23 17:18 ` Naveen N Rao
2025-04-23 20:36 ` Dan Williams
2025-04-24 6:35 ` Naveen N Rao
2025-04-28 15:53 ` Dave Hansen
2025-04-28 16:30 ` Jianxiong Gao
2025-04-28 16:36 ` Dave Hansen
2025-05-07 5:44 ` [PATCH v3 " kernel test robot
2025-04-22 14:09 ` [PATCH v3 0/2] Restrict devmem for confidential VMs Nikolay Borisov
2025-04-28 15:50 ` Dave Hansen
2025-04-28 22:48 ` Dan Williams
2025-04-29 0:37 ` Dave Hansen
2025-04-30 15:41 ` Suzuki K Poulose
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