From: Sohil Mehta <sohil.mehta@intel.com>
To: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>, <x86@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>,
Peter Zijlstra <peterz@infradead.org>,
Ard Biesheuvel <ardb@kernel.org>,
"Paul E. McKenney" <paulmck@kernel.org>,
Josh Poimboeuf <jpoimboe@kernel.org>,
Xiongwei Song <xiongwei.song@windriver.com>,
Xin Li <xin3.li@intel.com>,
"Mike Rapoport (IBM)" <rppt@kernel.org>,
Brijesh Singh <brijesh.singh@amd.com>,
Michael Roth <michael.roth@amd.com>,
Tony Luck <tony.luck@intel.com>,
Alexey Kardashevskiy <aik@amd.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jonathan Corbet <corbet@lwn.net>,
"Ingo Molnar" <mingo@kernel.org>,
Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
Daniel Sneddon <daniel.sneddon@linux.intel.com>,
Kai Huang <kai.huang@intel.com>,
Sandipan Das <sandipan.das@amd.com>,
Breno Leitao <leitao@debian.org>,
Rick Edgecombe <rick.p.edgecombe@intel.com>,
"Alexei Starovoitov" <ast@kernel.org>,
Hou Tao <houtao1@huawei.com>, Juergen Gross <jgross@suse.com>,
Vegard Nossum <vegard.nossum@oracle.com>,
Kees Cook <kees@kernel.org>, Eric Biggers <ebiggers@google.com>,
Jason Gunthorpe <jgg@ziepe.ca>,
"Masami Hiramatsu (Google)" <mhiramat@kernel.org>,
"Andrew Morton" <akpm@linux-foundation.org>,
Luis Chamberlain <mcgrof@kernel.org>,
Yuntao Wang <ytcoode@gmail.com>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
Christophe Leroy <christophe.leroy@csgroup.eu>,
Tejun Heo <tj@kernel.org>, Changbin Du <changbin.du@huawei.com>,
Huang Shijie <shijie@os.amperecomputing.com>,
Geert Uytterhoeven <geert+renesas@glider.be>,
Namhyung Kim <namhyung@kernel.org>,
"Arnaldo Carvalho de Melo" <acme@redhat.com>,
<linux-doc@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
<linux-efi@vger.kernel.org>, <linux-mm@kvack.org>
Subject: Re: [PATCHv8 14/17] x86/traps: Handle LASS thrown #SS
Date: Wed, 2 Jul 2025 13:05:17 -0700 [thread overview]
Message-ID: <bbe9dfb6-88c7-4724-bafd-0524599c9369@intel.com> (raw)
In-Reply-To: <mgo3qfjekobe6qflwkpey3p7tzsp3b2mrirama4w2rxyckce7g@3gce3fn5emvu>
On 7/2/2025 6:27 AM, Kirill A. Shutemov wrote:
>>
>> Maybe I've misunderstood something:
>>
>> Is the underlying assumption here that #SS were previously only
>> generated by userspace, but now they can also be generated by the
>> kernel? And we want the kernel generated #SS to behave the same as the #GP?
>
> It can be generated by both kernel and userspace if RSP gets corrupted.
>
> So far, do_error_trap() did the trick, handling what has to be handled.
> LASS requires a bit more, though.
>
Thank you for the information! The discussion in the other thread helped
clarify my confusion about the new FRED specific fixup outside the LASS
check.
IIUC, for kernel generated #SS, the prior code in do_error_trap()
would've done a few things such as notify_die() and
cond_local_irq_enable() before calling die().
The new code now directly calls die_addr(). Are we changing the behavior
for legacy kernel #SS? Also, why don't we need those calls for the new
LASS #SS?
I apologize if the questions seem too naive. I am finding the exception
handling code a bit convoluted to understand. In general, I would
suggest adding some code comments at least for the new code to help
ignorant folks like me looking at this in the future.
next prev parent reply other threads:[~2025-07-02 20:05 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20250701095849.2360685-1-kirill.shutemov@linux.intel.com>
[not found] ` <20250701095849.2360685-4-kirill.shutemov@linux.intel.com>
2025-07-01 18:44 ` [PATCHv8 03/17] x86/alternatives: Disable LASS when patching kernel alternatives Sohil Mehta
[not found] ` <20250701095849.2360685-12-kirill.shutemov@linux.intel.com>
2025-07-01 22:51 ` [PATCHv8 11/17] x86/cpu: Set LASS CR4 bit as pinning sensitive Sohil Mehta
[not found] ` <20250701095849.2360685-16-kirill.shutemov@linux.intel.com>
2025-07-01 23:03 ` [PATCHv8 15/17] x86/cpu: Make LAM depend on LASS Sohil Mehta
[not found] ` <20250701095849.2360685-5-kirill.shutemov@linux.intel.com>
2025-07-01 19:03 ` [PATCHv8 04/17] x86/cpu: Defer CR pinning setup until after EFI initialization Sohil Mehta
2025-07-02 9:47 ` Kirill A. Shutemov
2025-07-01 23:10 ` Dave Hansen
2025-07-02 10:05 ` Kirill A. Shutemov
2025-07-04 12:23 ` Kirill A. Shutemov
[not found] ` <20250701095849.2360685-18-kirill.shutemov@linux.intel.com>
2025-07-01 23:13 ` [PATCHv8 17/17] x86: Re-enable Linear Address Masking Sohil Mehta
[not found] ` <20250701095849.2360685-13-kirill.shutemov@linux.intel.com>
2025-07-02 0:36 ` [PATCHv8 12/17] x86/traps: Communicate a LASS violation in #GP message Sohil Mehta
2025-07-02 10:10 ` Kirill A. Shutemov
[not found] ` <20250701095849.2360685-14-kirill.shutemov@linux.intel.com>
2025-07-02 0:54 ` [PATCHv8 13/17] x86/traps: Generalize #GP address decode and hint code Sohil Mehta
[not found] ` <20250701095849.2360685-15-kirill.shutemov@linux.intel.com>
2025-07-02 1:35 ` [PATCHv8 14/17] x86/traps: Handle LASS thrown #SS Sohil Mehta
2025-07-02 2:00 ` H. Peter Anvin
2025-07-02 2:06 ` H. Peter Anvin
2025-07-02 10:17 ` Kirill A. Shutemov
2025-07-02 14:37 ` H. Peter Anvin
2025-07-02 14:47 ` Kirill A. Shutemov
2025-07-02 17:10 ` H. Peter Anvin
2025-07-02 23:42 ` Andrew Cooper
2025-07-03 0:44 ` H. Peter Anvin
2025-07-06 9:22 ` David Laight
2025-07-06 15:07 ` H. Peter Anvin
2025-07-02 13:27 ` Kirill A. Shutemov
2025-07-02 17:56 ` Sohil Mehta
2025-07-03 10:40 ` Kirill A. Shutemov
2025-07-02 20:05 ` Sohil Mehta [this message]
2025-07-03 11:31 ` Kirill A. Shutemov
2025-07-03 20:12 ` Sohil Mehta
2025-07-04 9:23 ` Kirill A. Shutemov
[not found] ` <20250701095849.2360685-3-kirill.shutemov@linux.intel.com>
2025-07-03 8:44 ` [PATCHv8 02/17] x86/asm: Introduce inline memcpy and memset David Laight
2025-07-03 10:39 ` Kirill A. Shutemov
2025-07-03 12:15 ` David Laight
2025-07-03 13:33 ` Vegard Nossum
2025-07-03 16:52 ` David Laight
2025-07-03 14:10 ` Kirill A. Shutemov
2025-07-03 17:02 ` David Laight
2025-07-03 17:13 ` Dave Hansen
2025-07-04 9:04 ` Kirill A. Shutemov
2025-07-06 9:13 ` David Laight
2025-07-07 8:02 ` Kirill A. Shutemov
2025-07-07 9:33 ` David Laight
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