linux-kernel - Re: [PATCH v2] KVM: x86: Don't read guest CR3 when doing async pf while the MMU is direct

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <2df1a0c0-31a6-45c9-a92e-abdbfddbd9b6@intel.com>
Date: Mon, 15 Dec 2025 10:30:06 +0800
From: Xiaoyao Li <xiaoyao.li@...el.com>
To: Sean Christopherson <seanjc@...gle.com>, kernel test robot <lkp@...el.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>, oe-kbuild-all@...ts.linux.dev,
 Rick Edgecombe <rick.p.edgecombe@...el.com>, kvm@...r.kernel.org,
 linux-kernel@...r.kernel.org, farrah.chen@...el.com
Subject: Re: [PATCH v2] KVM: x86: Don't read guest CR3 when doing async pf
 while the MMU is direct

On 12/13/2025 9:01 AM, Sean Christopherson wrote:
> On Sat, Dec 13, 2025, kernel test robot wrote:
>> Hi Xiaoyao,
>>
>> kernel test robot noticed the following build warnings:
>>
>> [auto build test WARNING on 7d0a66e4bb9081d75c82ec4957c50034cb0ea449]
>>
>> url:    https://github.com/intel-lab-lkp/linux/commits/Xiaoyao-Li/KVM-x86-Don-t-read-guest-CR3-when-doing-async-pf-while-the-MMU-is-direct/20251212-220612
>> base:   7d0a66e4bb9081d75c82ec4957c50034cb0ea449
>> patch link:    https://lore.kernel.org/r/20251212135051.2155280-1-xiaoyao.li%40intel.com
>> patch subject: [PATCH v2] KVM: x86: Don't read guest CR3 when doing async pf while the MMU is direct
>> config: i386-buildonly-randconfig-002-20251213 (https://download.01.org/0day-ci/archive/20251213/202512130717.aHH8rXSC-lkp@intel.com/config)
>> compiler: gcc-14 (Debian 14.2.0-19) 14.2.0
>> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251213/202512130717.aHH8rXSC-lkp@intel.com/reproduce)
>>
>> If you fix the issue in a separate patch/commit (i.e. not just a new version of
>> the same patch/commit), kindly add following tags
>> | Reported-by: kernel test robot <lkp@...el.com>
>> | Closes: https://lore.kernel.org/oe-kbuild-all/202512130717.aHH8rXSC-lkp@intel.com/
>>
>> All warnings (new ones prefixed by >>):
>>
>>     In file included from include/linux/kvm_host.h:43,
>>                      from arch/x86/kvm/irq.h:15,
>>                      from arch/x86/kvm/mmu/mmu.c:19:
>>     arch/x86/kvm/mmu/mmu.c: In function 'kvm_arch_setup_async_pf':
>>>> include/linux/kvm_types.h:54:25: warning: conversion from 'long long unsigned int' to 'long unsigned int' changes value from '18446744073709551615' to '4294967295' [-Woverflow]
>>        54 | #define INVALID_GPA     (~(gpa_t)0)
>>           |                         ^
>>     arch/x86/kvm/mmu/mmu.c:4525:28: note: in expansion of macro 'INVALID_GPA'
>>      4525 |                 arch.cr3 = INVALID_GPA;
>>           |                            ^~~~~~~~~~~
> 
> Well that's just annoying.  Can we kill 32-bit yet?  Anyways, just ignore this
> (unless it causes my KVM_WERROR=1 builds to fail, in which case I'll just add an
> explicit cast, but I think we can just ignore it).

If your KVM_WERROR=1 builds contain 32-bit config, I think it will fail. 
I think we do need to add the explicit cast.

You will handle it when applying, right? Thus no need for a v3.