diff options
| author | Paolo Bonzini <pbonzini@redhat.com> | 2023-11-25 03:33:59 -0500 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2023-12-01 07:52:08 -0800 |
| commit | 250ce1b4d21a94f910c3df5141ff6434ea92524e (patch) | |
| tree | e04b9c330262a9edbb83ce90a729ee8f200ab279 /arch/x86/include/asm/kvm_host.h | |
| parent | 484dd27c0602e01cb49db362ad42b95e70912d43 (diff) | |
KVM: x86/mmu: always take tdp_mmu_pages_lock
It is cheap to take tdp_mmu_pages_lock in all write-side critical sections.
We already do it all the time when zapping with read_lock(), so it is not
a problem to do it from the kvm_tdp_mmu_zap_all() path (aka
kvm_arch_flush_shadow_all(), aka VM destruction and MMU notifier release).
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Link: https://lore.kernel.org/r/20231125083400.1399197-4-pbonzini@redhat.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Diffstat (limited to 'arch/x86/include/asm/kvm_host.h')
| -rw-r--r-- | arch/x86/include/asm/kvm_host.h | 11 |
1 files changed, 6 insertions, 5 deletions
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index a565a2e70f30..414691169a04 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1407,9 +1407,8 @@ struct kvm_arch { * the MMU lock in read mode + RCU or * the MMU lock in write mode * - * For writes, this list is protected by: - * the MMU lock in read mode + the tdp_mmu_pages_lock or - * the MMU lock in write mode + * For writes, this list is protected by tdp_mmu_pages_lock; see + * below for the details. * * Roots will remain in the list until their tdp_mmu_root_count * drops to zero, at which point the thread that decremented the @@ -1426,8 +1425,10 @@ struct kvm_arch { * - possible_nx_huge_pages; * - the possible_nx_huge_page_link field of kvm_mmu_page structs used * by the TDP MMU - * It is acceptable, but not necessary, to acquire this lock when - * the thread holds the MMU lock in write mode. + * Because the lock is only taken within the MMU lock, strictly + * speaking it is redundant to acquire this lock when the thread + * holds the MMU lock in write mode. However it often simplifies + * the code to do so. */ spinlock_t tdp_mmu_pages_lock; #endif /* CONFIG_X86_64 */ |