Re: [PATCH v3 2/2] KVM: x86/mmu: Recover TDP MMU NX huge pages using MMU read lock

[Vipin Sharma <vipinsh@google.com>]

On 2024-09-09 07:29:55, kernel test robot wrote:
> Hi Vipin,
> 
> kernel test robot noticed the following build errors:
> 
> [auto build test ERROR on 332d2c1d713e232e163386c35a3ba0c1b90df83f]
> 
> url:    https://github.com/intel-lab-lkp/linux/commits/Vipin-Sharma/KVM-x86-mmu-Track-TDP-MMU-NX-huge-pages-separately/20240907-044800
> base:   332d2c1d713e232e163386c35a3ba0c1b90df83f
> patch link:    https://lore.kernel.org/r/20240906204515.3276696-3-vipinsh%40google.com
> patch subject: [PATCH v3 2/2] KVM: x86/mmu: Recover TDP MMU NX huge pages using MMU read lock
> config: i386-randconfig-005-20240908 (https://download.01.org/0day-ci/archive/20240909/202409090949.xuOxMsJ2-lkp@intel.com/config)
> compiler: clang version 18.1.5 (https://github.com/llvm/llvm-project 617a15a9eac96088ae5e9134248d8236e34b91b1)
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240909/202409090949.xuOxMsJ2-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@intel.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202409090949.xuOxMsJ2-lkp@intel.com/
> 
> All errors (new ones prefixed by >>):
> 
> >> ld.lld: error: undefined symbol: kvm_tdp_mmu_zap_possible_nx_huge_page
>    >>> referenced by mmu.c:7415 (arch/x86/kvm/mmu/mmu.c:7415)
>    >>>               arch/x86/kvm/mmu/mmu.o:(kvm_recover_nx_huge_pages) in archive vmlinux.a

I missed it because i386 command I used was from config given in v1 of
the series by lkp bot. That command was just for build kvm directory and
ldd didn't get invoke.

I will send out a new version after collecting feedback on this version
of the series. I am thinking of below change to fix the error.

diff --git a/arch/x86/kvm/mmu/tdp_mmu.h b/arch/x86/kvm/mmu/tdp_mmu.h
index ed4bdceb9aec..37620496f64a 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.h
+++ b/arch/x86/kvm/mmu/tdp_mmu.h
@@ -20,8 +20,6 @@ __must_check static inline bool kvm_tdp_mmu_get_root(struct kvm_mmu_page *root)
 void kvm_tdp_mmu_put_root(struct kvm *kvm, struct kvm_mmu_page *root);

 bool kvm_tdp_mmu_zap_leafs(struct kvm *kvm, gfn_t start, gfn_t end, bool flush);
-bool kvm_tdp_mmu_zap_possible_nx_huge_page(struct kvm *kvm,
-                                          struct kvm_mmu_page *sp);
 void kvm_tdp_mmu_zap_all(struct kvm *kvm);
 void kvm_tdp_mmu_invalidate_all_roots(struct kvm *kvm);
 void kvm_tdp_mmu_zap_invalidated_roots(struct kvm *kvm);
@@ -73,8 +71,17 @@ void kvm_tdp_mmu_recover_nx_huge_pages(struct kvm *kvm);

 #ifdef CONFIG_X86_64
 static inline bool is_tdp_mmu_page(struct kvm_mmu_page *sp) { return sp->tdp_mmu_page; }
+bool kvm_tdp_mmu_zap_possible_nx_huge_page(struct kvm *kvm,
+                                          struct kvm_mmu_page *sp);
 #else
 static inline bool is_tdp_mmu_page(struct kvm_mmu_page *sp) { return false; }
+static bool kvm_tdp_mmu_zap_possible_nx_huge_page(struct kvm *kvm,
+                                          struct kvm_mmu_page *sp)
+{
+       WARN_ONCE(1, "TDP MMU not supported in 32bit builds");
+       return false;
+}
+
 #endif

 #endif /* __KVM_X86_MMU_TDP_MMU_H */


> 
> -- 
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests/wiki