diff options
| author | Ben Gardon <bgardon@google.com> | 2021-04-01 16:37:31 -0700 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2021-04-19 09:06:01 -0400 |
| commit | c0e64238ac53e8226e3fe72279e5e76253e85f88 (patch) | |
| tree | 37c35adf04618825ada74f921afd773835fc4ecf /arch/x86/include | |
| parent | fb10129335ca6cc7a229226b03f54394757d773d (diff) | |
| download | linux-c0e64238ac53e8226e3fe72279e5e76253e85f88.tar.bz2 | |
KVM: x86/mmu: Protect the tdp_mmu_roots list with RCU
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@google.com>
Message-Id: <20210401233736.638171-9-bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/include')
| -rw-r--r-- | arch/x86/include/asm/kvm_host.h | 21 |
1 files changed, 16 insertions, 5 deletions
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 0d217c3db3f8..2f6f4aeca6b7 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1059,25 +1059,36 @@ struct kvm_arch { bool tdp_mmu_enabled; /* - * List of struct kvmp_mmu_pages being used as roots. + * List of struct kvm_mmu_pages being used as roots. * All struct kvm_mmu_pages in the list should have * tdp_mmu_page set. - * All struct kvm_mmu_pages in the list should have a positive - * root_count except when a thread holds the MMU lock and is removing - * an entry from the list. + * + * For reads, this list is protected by: + * 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 + * + * Roots will remain in the list until their tdp_mmu_root_count + * drops to zero, at which point the thread that decremented the + * count to zero should removed the root from the list and clean + * it up, freeing the root after an RCU grace period. */ struct list_head tdp_mmu_roots; /* * List of struct kvmp_mmu_pages not being used as roots. * All struct kvm_mmu_pages in the list should have - * tdp_mmu_page set and a root_count of 0. + * tdp_mmu_page set and a tdp_mmu_root_count of 0. */ struct list_head tdp_mmu_pages; /* * Protects accesses to the following fields when the MMU lock * is held in read mode: + * - tdp_mmu_roots (above) * - tdp_mmu_pages (above) * - the link field of struct kvm_mmu_pages used by the TDP MMU * - lpage_disallowed_mmu_pages |