From: Dave Hansen <dave.hansen@intel.com>
To: Sohil Mehta <sohil.mehta@intel.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, Andy Lutomirski <luto@kernel.org>,
Borislav Petkov <bp@alien8.de>
Cc: Jonathan Corbet <corbet@lwn.net>,
Shuah Khan <skhan@linuxfoundation.org>,
Thomas Gleixner <tglx@kernel.org>, Ingo Molnar <mingo@redhat.com>,
"H . Peter Anvin" <hpa@zytor.com>,
Peter Zijlstra <peterz@infradead.org>,
Kiryl Shutsemau <kas@kernel.org>,
Brendan Jackman <jackmanb@google.com>,
Sean Christopherson <seanjc@google.com>,
Nam Cao <namcao@linutronix.de>,
Cedric Xing <cedric.xing@intel.com>,
Rick Edgecombe <rick.p.edgecombe@intel.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
Tony Luck <tony.luck@intel.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Maciej Wieczor-Retman <m.wieczorretman@pm.me>,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/5] x86: Enable LASS support with vsyscall emulation
Date: Tue, 3 Mar 2026 08:27:26 -0800 [thread overview]
Message-ID: <b044b3cf-ce30-44f6-b3ee-ce552407e95a@intel.com> (raw)
In-Reply-To: <20260219233600.154313-1-sohil.mehta@intel.com>
On 2/19/26 15:35, Sohil Mehta wrote:
> These patches primarily update the #GP handler to reuse the existing
> vsyscall emulation code for #PF. In XONLY mode, the faulting RIP is
> readily available and can be used to determine if the #GP was triggered
> due to a vsyscall access.
>
> In contrast, the vsyscall EMULATE mode is deprecated and not expected to
> be used by anyone. Supporting EMULATE mode with LASS would require
> complex instruction decoding in the #GP fault handler, which is not
> worth the effort. So, LASS is disabled in the rare case when someone
> absolutely needs to enable vsyscall=emulate via the command line.
So this part is actually pretty nice.
Could we forklift a bit of this into patch 3, please?
prev parent reply other threads:[~2026-03-03 16:27 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-19 23:35 [PATCH 0/5] x86: Enable LASS support with vsyscall emulation Sohil Mehta
2026-02-19 23:35 ` [PATCH 1/5] x86/vsyscall: Reorganize the page fault emulation code Sohil Mehta
2026-02-19 23:35 ` [PATCH 2/5] x86/traps: Consolidate user fixups in the #GP handler Sohil Mehta
2026-02-19 23:35 ` [PATCH 3/5] x86/vsyscall: Add vsyscall emulation for #GP Sohil Mehta
2026-03-03 15:51 ` Dave Hansen
2026-03-03 21:20 ` Sohil Mehta
2026-03-03 22:35 ` H. Peter Anvin
2026-03-05 0:10 ` Sohil Mehta
2026-03-05 1:45 ` Dave Hansen
2026-03-05 6:31 ` H. Peter Anvin
2026-03-05 7:56 ` Sohil Mehta
2026-03-05 6:32 ` H. Peter Anvin
2026-02-19 23:35 ` [PATCH 4/5] x86/vsyscall: Disable LASS if vsyscall mode is set to EMULATE Sohil Mehta
2026-03-03 16:33 ` Dave Hansen
2026-02-19 23:36 ` [PATCH 5/5] x86/cpu: Remove LASS restriction on vsyscall emulation Sohil Mehta
2026-03-03 16:37 ` Dave Hansen
2026-03-03 16:27 ` Dave Hansen [this message]
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