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Peter Anvin" To: David Laight CC: Sohil Mehta , "Kirill A. Shutemov" , Andy Lutomirski , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, Peter Zijlstra , Ard Biesheuvel , "Paul E. McKenney" , Josh Poimboeuf , Xiongwei Song , Xin Li , "Mike Rapoport (IBM)" , Brijesh Singh , Michael Roth , Tony Luck , Alexey Kardashevskiy , Alexander Shishkin , Jonathan Corbet , Ingo Molnar , Pawan Gupta , Daniel Sneddon , Kai Huang , Sandipan Das , Breno Leitao , Rick Edgecombe , Alexei Starovoitov , Hou Tao , Juergen Gross , Vegard Nossum , Kees Cook , Eric Biggers , Jason Gunthorpe , "Masami Hiramatsu (Google)" , Andrew Morton , Luis Chamberlain , Yuntao Wang , Rasmus Villemoes , Christophe Leroy , Tejun Heo , Changbin Du , Huang Shijie , Geert Uytterhoeven , Namhyung Kim , Arnaldo Carvalho de Melo , 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 User-Agent: K-9 Mail for Android In-Reply-To: <20250706102213.4ab365d7@pumpkin> References: <20250701095849.2360685-1-kirill.shutemov@linux.intel.com> <20250701095849.2360685-15-kirill.shutemov@linux.intel.com> <95dc18fd-73b0-4019-92d2-c0e6aaf22c96@intel.com> <4DE45AFD-C1E0-4FB8-BE01-44A72C5C6E1E@zytor.com> <20250706102213.4ab365d7@pumpkin> Message-ID: <29992EA3-8BEE-4B31-A38F-F3E65FA9609D@zytor.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 40BF240002 X-Stat-Signature: fs3g3q84ricusrp9i7e5t45qmi1rmqad X-Rspam-User: X-HE-Tag: 1751814496-364085 X-HE-Meta: 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 /V/gd6mN JpAT1eQahwunsg5IdHOtRzAFHPiz5/NFOoLZdfWIBH+le6NfsNIzEu3RoZ1iCmX5u8l0tHidv82zZxbhY30IpOiKytberpscTVmq00EtSZjDvuziZgiNSJFnAWNxXXfqM3QAHsxgXHuapUxVJVJPjdqWpiX+TZBvOYTwZqg5fTEwxkRqU1GiLv33ae05EYk41QGsDyfn7NLupeRUrBcDhLuDhsOH6ZC3sBaMfMrX/EN3xXJvzclIv0+feZ2Ivo+k+sWFOo2JA9sU3Ny9SWZcLprvQqtDZSr+Zezs4jAea9k16MiFR+GX3VlxBi4nEoBEv97Jojv8sSv+v/03hFCT3IIDBl/hpIjfxESYani7r71BJ4Bf7xm6cJT6G6JqAl4PImbBDQ+XCKhyLmrm/61k//YCfHYd3CqoHuoUmGqVVS+Fn3coju9OEIrVGqzt+3b8LPo+A+jG36bhJqeo= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On July 6, 2025 2:22:13 AM PDT, David Laight wrote: >On Tue, 01 Jul 2025 19:06:10 -0700 >"H=2E Peter Anvin" wrote: >=2E=2E=2E >> Note: for a FRED system, ERETU can generate #SS for a non-canonical use= r space >> RSP even in the absence of LASS, so if that is not currently handled th= at is an active bug=2E > >Is that a fault in kernel space, or a fault in user space=2E=20 > >Some of the traps for 'iret' happen after the transition to user space, >so the kernel doesn't have to handle them as special cases=2E >(I simplified (and fixed) one version of that code=2E) > > David > It's a fault in user space=2E I had a brain fart and managed to forget tha= t RSP is technically a GPR and as such is not limited to the VA width of th= e machine=2E