On 31/03/21 23:08, Ben Gardon wrote:
Protect the contents of the TDP MMU roots list with RCU in preparation for a future patch which will allow the iterator macro to be used under the MMU lock in read mode. Signed-off-by: Ben Gardon<bgardon@xxxxxxxxxx> --- arch/x86/kvm/mmu/tdp_mmu.c | 64 +++++++++++++++++++++----------------- 1 file changed, 36 insertions(+), 28 deletions(-) diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c + spin_lock(&kvm->arch.tdp_mmu_pages_lock); + list_del_rcu(&root->link); + spin_unlock(&kvm->arch.tdp_mmu_pages_lock);
Please update the comment above tdp_mmu_pages_lock in arch/x86/include/asm/kvm_host.h as well.
/* Only safe under the MMU lock in write mode, without yielding. */ #define for_each_tdp_mmu_root(_kvm, _root) \ - list_for_each_entry(_root, &_kvm->arch.tdp_mmu_roots, link) + list_for_each_entry_rcu(_root, &_kvm->arch.tdp_mmu_roots, link, \ + lockdep_is_held_write(&kvm->mmu_lock))
This should also add "... || lockdep_is_help(&kvm->arch.tdp_mmu_pages_lock)", if only for documentation purposes.
Paolo
