| Message ID | 20241111183935.8550-1-advaitdhamorikar@gmail.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [PATCH-next] KVM: x86/tdp_mmu: Fix redundant u16 compared to 0 | expand |
On Tue, Nov 12, 2024, Advait Dhamorikar wrote: > An unsigned value can never be negative, > so this test will always evaluate the same way. > `_as_id` a u16 is compared to 0. Please wrap changelogs at ~75 characters. > Signed-off-by: Advait Dhamorikar <advaitdhamorikar@gmail.com> > --- > arch/x86/kvm/mmu/tdp_mmu.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c > index 4508d868f1cd..b4e7b6a264d6 100644 > --- a/arch/x86/kvm/mmu/tdp_mmu.c > +++ b/arch/x86/kvm/mmu/tdp_mmu.c > @@ -153,7 +153,7 @@ static struct kvm_mmu_page *tdp_mmu_next_root(struct kvm *kvm, > for (_root = tdp_mmu_next_root(_kvm, NULL, _only_valid); \ > ({ lockdep_assert_held(&(_kvm)->mmu_lock); }), _root; \ > _root = tdp_mmu_next_root(_kvm, _root, _only_valid)) \ > - if (_as_id >= 0 && kvm_mmu_page_as_id(_root) != _as_id) { \ > + if (kvm_mmu_page_as_id(_root) != _as_id) { \ NAK, the comparison is necessary as kvm_tdp_mmu_zap_leafs() deliberately invokes for_each_valid_tdp_mmu_root_yield_safe() => __for_each_tdp_mmu_root_yield_safe() with -1 to iterate over all address spaces. And I don't want to drop the check for __for_each_tdp_mmu_root(), even though there aren't any _current_ users that pass -1, as I want to keep the iterators symmetrical.
Hello Sean, > NAK, the comparison is necessary as kvm_tdp_mmu_zap_leafs() deliberately invokes > for_each_valid_tdp_mmu_root_yi > eld_safe() => __for_each_tdp_mmu_root_yield_safe() >with -1 to iterate over all address spaces. > And I don't want to drop the check for __for_each_tdp_mmu_root(), even though > there aren't any _current_ users that pass -1, as I want to keep the iterators > symmetrical. Understood, thanks for the feedback. Best regards, Advait On Tue, 12 Nov 2024 at 00:26, Sean Christopherson <seanjc@google.com> wrote: > > On Tue, Nov 12, 2024, Advait Dhamorikar wrote: > > An unsigned value can never be negative, > > so this test will always evaluate the same way. > > `_as_id` a u16 is compared to 0. > > Please wrap changelogs at ~75 characters. > > > Signed-off-by: Advait Dhamorikar <advaitdhamorikar@gmail.com> > > --- > > arch/x86/kvm/mmu/tdp_mmu.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c > > index 4508d868f1cd..b4e7b6a264d6 100644 > > --- a/arch/x86/kvm/mmu/tdp_mmu.c > > +++ b/arch/x86/kvm/mmu/tdp_mmu.c > > @@ -153,7 +153,7 @@ static struct kvm_mmu_page *tdp_mmu_next_root(struct kvm *kvm, > > for (_root = tdp_mmu_next_root(_kvm, NULL, _only_valid); \ > > ({ lockdep_assert_held(&(_kvm)->mmu_lock); }), _root; \ > > _root = tdp_mmu_next_root(_kvm, _root, _only_valid)) \ > > - if (_as_id >= 0 && kvm_mmu_page_as_id(_root) != _as_id) { \ > > + if (kvm_mmu_page_as_id(_root) != _as_id) { \ > > NAK, the comparison is necessary as kvm_tdp_mmu_zap_leafs() deliberately invokes > for_each_valid_tdp_mmu_root_yield_safe() => __for_each_tdp_mmu_root_yield_safe() > with -1 to iterate over all address spaces. > > And I don't want to drop the check for __for_each_tdp_mmu_root(), even though > there aren't any _current_ users that pass -1, as I want to keep the iterators > symmetrical.
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 4508d868f1cd..b4e7b6a264d6 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -153,7 +153,7 @@ static struct kvm_mmu_page *tdp_mmu_next_root(struct kvm *kvm, for (_root = tdp_mmu_next_root(_kvm, NULL, _only_valid); \ ({ lockdep_assert_held(&(_kvm)->mmu_lock); }), _root; \ _root = tdp_mmu_next_root(_kvm, _root, _only_valid)) \ - if (_as_id >= 0 && kvm_mmu_page_as_id(_root) != _as_id) { \ + if (kvm_mmu_page_as_id(_root) != _as_id) { \ } else #define for_each_valid_tdp_mmu_root_yield_safe(_kvm, _root, _as_id) \
An unsigned value can never be negative, so this test will always evaluate the same way. `_as_id` a u16 is compared to 0. Signed-off-by: Advait Dhamorikar <advaitdhamorikar@gmail.com> --- arch/x86/kvm/mmu/tdp_mmu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)