From: Sohil Mehta <sohil.mehta@intel.com>
To: Dave Hansen <dave.hansen@intel.com>,
Yian Chen <yian.chen@intel.com>, <linux-kernel@vger.kernel.org>,
<x86@kernel.org>, Andy Lutomirski <luto@kernel.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
Ravi Shankar <ravi.v.shankar@intel.com>,
Tony Luck <tony.luck@intel.com>, Paul Lai <paul.c.lai@intel.com>
Subject: Re: [PATCH 5/7] x86/cpu: Enable LASS (Linear Address Space Separation)
Date: Thu, 12 Jan 2023 17:17:53 -0800 [thread overview]
Message-ID: <f6d16f82-9cbe-993d-88aa-1644e89c4fe7@intel.com> (raw)
In-Reply-To: <7e859e72-4624-73c7-8195-c252ace0a49d@intel.com>
On 1/12/2023 10:17 AM, Dave Hansen wrote:
> In the end, want X86_CR4_LASS set when the kernel wants LASS and clear
> in *ALL* other cases. That would be simply:
>
> if (cpu_feature_enabled(X86_FEATURE_LASS)) {
> cr4_set_bits(X86_CR4_LASS);
> } else {
> cr4_clear_bits(X86_CR4_LASS);
> }
>
Thanks for the explanation. This is very helpful.
> I'm also wondering if we even want a Kconfig option. Is anyone
> realistically going to be compiling this support out?
I was initially thinking we should leave the Kconfig option for users
that really *need* vsyscall support. But, thinking about it more, we
don't need an LASS Kconfig option for that.
We can make CONFIG_LEGACY_VSYSCALL_NONE as the default instead of the
current CONFIG_LEGACY_VSYSCALL_XONLY. The kernel can disable LASS at
boot time if a user/admin has shown explicit preference by selecting
CONFIG_LEGACY_VSYSCALL_XONLY or by providing command line parameter
vsyscall=xonly/emulate.
Thoughts?
next prev parent reply other threads:[~2023-01-13 1:18 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-10 5:51 [PATCH 0/7] Enable LASS (Linear Address space Separation) Yian Chen
2023-01-10 5:51 ` [PATCH 1/7] x86/cpu: Enumerate LASS CPUID and CR4 bits Yian Chen
2023-01-10 20:14 ` Sohil Mehta
2023-01-11 0:13 ` Dave Hansen
2023-01-11 23:23 ` Chen, Yian
2023-01-12 0:06 ` Luck, Tony
2023-01-12 0:15 ` Chen, Yian
2023-01-11 19:21 ` Chen, Yian
2023-01-10 5:51 ` [PATCH 2/7] x86: Add CONFIG option X86_LASS Yian Chen
2023-01-10 21:05 ` Sohil Mehta
2023-01-12 0:13 ` Chen, Yian
2023-01-10 5:52 ` [PATCH 3/7] x86/cpu: Disable kernel LASS when patching kernel alternatives Yian Chen
2023-01-10 21:04 ` Peter Zijlstra
2023-01-11 1:01 ` Chen, Yian
2023-01-11 9:10 ` Peter Zijlstra
2023-01-10 22:41 ` Sohil Mehta
2023-01-12 0:27 ` Chen, Yian
2023-01-12 0:37 ` Dave Hansen
2023-01-12 18:36 ` Chen, Yian
2023-01-12 18:48 ` Dave Hansen
2023-02-01 2:25 ` Sohil Mehta
2023-02-01 18:20 ` Dave Hansen
2023-02-01 2:10 ` Sohil Mehta
2023-01-10 5:52 ` [PATCH 4/7] x86/vsyscall: Setup vsyscall to compromise LASS protection Yian Chen
2023-01-11 0:34 ` Sohil Mehta
2023-01-12 1:43 ` Chen, Yian
2023-01-12 2:49 ` Sohil Mehta
2023-01-21 4:09 ` Andy Lutomirski
2023-01-10 5:52 ` [PATCH 5/7] x86/cpu: Enable LASS (Linear Address Space Separation) Yian Chen
2023-01-11 22:22 ` Sohil Mehta
2023-01-12 17:56 ` Chen, Yian
2023-01-12 18:17 ` Dave Hansen
2023-01-13 1:17 ` Sohil Mehta [this message]
2023-01-13 19:39 ` Sohil Mehta
2023-01-10 5:52 ` [PATCH 6/7] x86/cpu: Set LASS as pinning sensitive CR4 bit Yian Chen
2023-01-10 5:52 ` [PATCH 7/7] x86/kvm: Expose LASS feature to VM guest Yian Chen
2023-02-07 3:21 ` Wang, Lei
2023-02-09 17:18 ` Sean Christopherson
2023-01-10 19:48 ` [PATCH 0/7] Enable LASS (Linear Address space Separation) Sohil Mehta
2023-01-10 22:57 ` Dave Hansen
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