From: Dave Hansen <dave.hansen@intel.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: acme@redhat.com, aik@amd.com, akpm@linux-foundation.org,
alexander.shishkin@linux.intel.com, ardb@kernel.org,
ast@kernel.org, bp@alien8.de, brijesh.singh@amd.com,
changbin.du@huawei.com, christophe.leroy@csgroup.eu,
corbet@lwn.net, daniel.sneddon@linux.intel.com,
dave.hansen@linux.intel.com, ebiggers@google.com,
geert+renesas@glider.be, houtao1@huawei.com, hpa@zytor.com,
jgg@ziepe.ca, jgross@suse.com, jpoimboe@kernel.org,
kai.huang@intel.com, kees@kernel.org,
kirill.shutemov@linux.intel.com, leitao@debian.org,
linux-doc@vger.kernel.org, linux-efi@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linux@rasmusvillemoes.dk, luto@kernel.org, mcgrof@kernel.org,
mhiramat@kernel.org, michael.roth@amd.com, mingo@kernel.org,
mingo@redhat.com, namhyung@kernel.org, paulmck@kernel.org,
pawan.kumar.gupta@linux.intel.com, peterz@infradead.org,
rick.p.edgecombe@intel.com, rppt@kernel.org,
sandipan.das@amd.com, shijie@os.amperecomputing.com,
sohil.mehta@intel.com, tglx@linutronix.de, tj@kernel.org,
tony.luck@intel.com, vegard.nossum@oracle.com, x86@kernel.org,
xin3.li@intel.com, xiongwei.song@windriver.com,
ytcoode@gmail.com
Subject: Re: [PATCHv6 07/16] x86/vsyscall: Reorganize the #PF emulation code
Date: Fri, 20 Jun 2025 16:21:38 -0700 [thread overview]
Message-ID: <b6f8a90d-4309-45c5-84cd-32e281d076fb@intel.com> (raw)
In-Reply-To: <262c0fd2-ac66-4ce7-903f-4062f1fe1d6e@citrix.com>
On 6/20/25 16:08, Andrew Cooper wrote:
>> But, the resulting code is wonky. It needs to do something more like this:
>>
>> if ((error_code & (X86_PF_WRITE | X86_PF_USER)) != X86_PF_USER)
>> return false;
>>
>> if (error_code & X86_PF_INSTR))
>> return __emulate_vsyscall(regs, address);
> To do this, LASS needs a proper interlink against NX || SMEP.
>
> If neither NX nor SMEP are active, the CPU does not report X86_PF_INSTR,
> meaning that fetches are reported as plain reads.
Interesting point.
I think the easiest way to do this is just make a cpuid_deps[] entry for
LASS and NX. If there's a CPU where LASS is available but where NX isn't
available, we have much bigger problems on our hands.
next prev parent reply other threads:[~2025-06-20 23:21 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20250620135325.3300848-1-kirill.shutemov@linux.intel.com>
[not found] ` <20250620135325.3300848-9-kirill.shutemov@linux.intel.com>
2025-06-20 14:47 ` [PATCHv6 08/16] x86/traps: Consolidate user fixups in exc_general_protection() Dave Hansen
[not found] ` <20250620135325.3300848-14-kirill.shutemov@linux.intel.com>
2025-06-20 15:20 ` [PATCHv6 13/16] x86/traps: Handle LASS thrown #SS Xin Li
2025-06-20 17:53 ` Kirill A. Shutemov
[not found] ` <20250620135325.3300848-4-kirill.shutemov@linux.intel.com>
2025-06-20 15:33 ` [PATCHv6 03/16] x86/alternatives: Disable LASS when patching kernel alternatives Dave Hansen
2025-06-20 17:18 ` Kirill A. Shutemov
[not found] ` <20250620135325.3300848-5-kirill.shutemov@linux.intel.com>
2025-06-20 15:35 ` [PATCHv6 04/16] x86/efi: Move runtime service initialization to arch/x86 Dave Hansen
2025-06-20 17:42 ` Kirill A. Shutemov
[not found] ` <20250620135325.3300848-2-kirill.shutemov@linux.intel.com>
2025-06-20 15:25 ` [PATCHv6 01/16] x86/cpu: Enumerate the LASS feature bits Dave Hansen
2025-06-20 15:36 ` Xin Li
2025-06-20 17:31 ` Kirill A. Shutemov
2025-06-20 23:46 ` Xin Li
2025-06-21 0:45 ` H. Peter Anvin
2025-06-21 0:50 ` H. Peter Anvin
2025-06-23 17:40 ` Xin Li
2025-06-24 2:04 ` H. Peter Anvin
2025-06-24 4:57 ` Xin Li
2025-06-24 5:11 ` Xin Li
2025-06-20 16:02 ` Randy Dunlap
2025-06-20 16:12 ` Xin Li
2025-06-20 16:16 ` Randy Dunlap
2025-06-20 16:35 ` Borislav Petkov
2025-06-20 17:33 ` Kirill A. Shutemov
2025-06-20 18:29 ` Borislav Petkov
2025-06-23 8:17 ` Kirill A. Shutemov
2025-06-23 10:21 ` Borislav Petkov
2025-06-23 13:42 ` Kirill A. Shutemov
2025-06-26 15:18 ` Borislav Petkov
2025-06-26 16:07 ` Borislav Petkov
2025-06-26 17:21 ` Dave Hansen
2025-06-27 10:25 ` Kirill A. Shutemov
2025-06-27 10:43 ` Borislav Petkov
2025-06-27 13:57 ` Dave Hansen
2025-06-20 18:14 ` Sohil Mehta
2025-06-20 18:24 ` Dave Hansen
2025-06-20 23:10 ` Sohil Mehta
2025-06-23 16:25 ` Luck, Tony
2025-06-23 16:42 ` Dave Hansen
2025-06-23 23:13 ` Luck, Tony
2025-06-23 23:36 ` H. Peter Anvin
2025-06-24 0:10 ` Luck, Tony
2025-06-24 2:03 ` H. Peter Anvin
2025-06-25 18:51 ` H. Peter Anvin
2025-06-20 15:38 ` [PATCHv6 00/16] x86: Enable Linear Address Space Separation support Dave Hansen
2025-06-20 22:04 ` Andrew Cooper
2025-06-20 22:29 ` H. Peter Anvin
2025-06-20 22:43 ` H. Peter Anvin
2025-06-20 22:46 ` Dave Hansen
[not found] ` <20250620135325.3300848-6-kirill.shutemov@linux.intel.com>
2025-06-20 15:44 ` [PATCHv6 05/16] x86/cpu: Defer CR pinning setup until after EFI initialization Dave Hansen
[not found] ` <20250620135325.3300848-7-kirill.shutemov@linux.intel.com>
2025-06-20 15:55 ` [PATCHv6 06/16] efi: Disable LASS around set_virtual_address_map() EFI call Dave Hansen
2025-06-20 17:50 ` Kirill A. Shutemov
[not found] ` <20250620135325.3300848-8-kirill.shutemov@linux.intel.com>
2025-06-20 18:43 ` [PATCHv6 07/16] x86/vsyscall: Reorganize the #PF emulation code Dave Hansen
2025-06-20 23:08 ` Andrew Cooper
2025-06-20 23:18 ` Sohil Mehta
2025-06-20 23:29 ` Andrew Cooper
2025-06-20 23:21 ` Dave Hansen [this message]
2025-06-21 3:35 ` H. Peter Anvin
2025-06-23 12:41 ` Kirill A. Shutemov
2025-06-23 12:46 ` Andrew Cooper
2025-06-23 15:32 ` Dave Hansen
2025-06-23 15:45 ` Andrew Cooper
2025-06-24 11:37 ` Kirill A. Shutemov
2025-06-24 14:11 ` Dave Hansen
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