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From: Dave Hansen <dave.hansen@intel.com>
To: Maciej Wieczor-Retman <maciej.wieczor-retman@intel.com>
Cc: shuah@kernel.org, hpa@zytor.com, x86@kernel.org,
	dave.hansen@linux.intel.com, bp@alien8.de, mingo@redhat.com,
	tglx@linutronix.de, linux-kernel@vger.kernel.org,
	linux-kselftest@vger.kernel.org, kirill@shutemov.name,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Shuah Khan <skhan@linuxfoundation.org>
Subject: Re: [PATCH v5 1/3] selftests/lam: Move cpu_has_la57() to use cpuinfo flag
Date: Fri, 24 Jan 2025 12:24:25 -0800	[thread overview]
Message-ID: <050c2ead-6261-4c46-8246-50c587eab227@intel.com> (raw)
In-Reply-To: <yu3pbemophlzqgd67xongzdflsj2yp722x5brj5ikaiyprxckm@b4vmk4kajxlc>

On 1/24/25 12:17, Maciej Wieczor-Retman wrote:
>> Could you poke around and see if there is any existing ABI that we can
>> use to query LA57 support? Maybe one of the things KVM exports, or some
>> TASK_SIZE_MAX comparisons?
> Sure, I'll try to find some other way.
> 
> My previous tactic was to munmap() a high address and see if it works. Does that
> sound okay in case there isn't anything else would indicate la57 to userspace
> reliably?

Yeah, I think that's fine. I can't think of any obvious horrible
pitfalls. All I'd ask is that you spend 20 minutes grepping for things
that are conditional on X86_FEATURE_LA57 and see if there's anything
else that's a good candidate.

  reply	other threads:[~2025-01-24 20:24 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-11-27 17:35 [PATCH v5 0/3] selftests/lam: get_user additions and LAM enabled check Maciej Wieczor-Retman
2024-11-27 17:35 ` [PATCH v5 1/3] selftests/lam: Move cpu_has_la57() to use cpuinfo flag Maciej Wieczor-Retman
2025-01-24 16:14   ` Dave Hansen
2025-01-24 20:17     ` Maciej Wieczor-Retman
2025-01-24 20:24       ` Dave Hansen [this message]
2025-01-24 20:29       ` Maciej Wieczor-Retman
2024-11-27 17:35 ` [PATCH v5 2/3] selftests/lam: Skip test if LAM is disabled Maciej Wieczor-Retman
2025-01-24 16:23   ` Dave Hansen
2025-01-24 20:09     ` Maciej Wieczor-Retman
2024-11-27 17:35 ` [PATCH v5 3/3] selftests/lam: Test get_user() LAM pointer handling Maciej Wieczor-Retman
2025-01-24 16:32   ` Dave Hansen
2025-01-24 20:19     ` Maciej Wieczor-Retman
2025-01-15  9:06 ` [PATCH v5 0/3] selftests/lam: get_user additions and LAM enabled check Maciej Wieczor-Retman
2025-01-23 21:52   ` Shuah Khan

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