| Message ID | 20240711222755.57476-11-pbonzini@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: guest_memfd: lazy preparation of pages + prefault support for SEV-SNP | expand |
On Thu, Jul 11, 2024 at 06:27:53PM -0400, Paolo Bonzini wrote: > Use a guard to simplify early returns, and add two more easy > shortcuts. If the requested attributes are invalid, the attributes > xarray will never show them as set. And if testing a single page, > kvm_get_memory_attributes() is more efficient. > > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> > --- > virt/kvm/kvm_main.c | 42 ++++++++++++++++++++---------------------- > 1 file changed, 20 insertions(+), 22 deletions(-) > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index f817ec66c85f..8ab9d8ff7b74 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -2392,6 +2392,14 @@ static int kvm_vm_ioctl_clear_dirty_log(struct kvm *kvm, > #endif /* CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT */ > > #ifdef CONFIG_KVM_GENERIC_MEMORY_ATTRIBUTES > +static u64 kvm_supported_mem_attributes(struct kvm *kvm) > +{ > + if (!kvm || kvm_arch_has_private_mem(kvm)) > + return KVM_MEMORY_ATTRIBUTE_PRIVATE; > + > + return 0; > +} > + > /* > * Returns true if _all_ gfns in the range [@start, @end) have attributes > * matching @attrs. > @@ -2400,40 +2408,30 @@ bool kvm_range_has_memory_attributes(struct kvm *kvm, gfn_t start, gfn_t end, > unsigned long attrs) > { > XA_STATE(xas, &kvm->mem_attr_array, start); > + unsigned long mask = kvm_supported_mem_attributes(kvm);; Extra semicolon. Otherwise: Reviewed-by: Michael Roth <michael.roth@amd.com>
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index f817ec66c85f..8ab9d8ff7b74 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2392,6 +2392,14 @@ static int kvm_vm_ioctl_clear_dirty_log(struct kvm *kvm, #endif /* CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT */ #ifdef CONFIG_KVM_GENERIC_MEMORY_ATTRIBUTES +static u64 kvm_supported_mem_attributes(struct kvm *kvm) +{ + if (!kvm || kvm_arch_has_private_mem(kvm)) + return KVM_MEMORY_ATTRIBUTE_PRIVATE; + + return 0; +} + /* * Returns true if _all_ gfns in the range [@start, @end) have attributes * matching @attrs. @@ -2400,40 +2408,30 @@ bool kvm_range_has_memory_attributes(struct kvm *kvm, gfn_t start, gfn_t end, unsigned long attrs) { XA_STATE(xas, &kvm->mem_attr_array, start); + unsigned long mask = kvm_supported_mem_attributes(kvm);; unsigned long index; - bool has_attrs; void *entry; - rcu_read_lock(); + if (attrs & ~mask) + return false; - if (!attrs) { - has_attrs = !xas_find(&xas, end - 1); - goto out; - } + if (end == start + 1) + return kvm_get_memory_attributes(kvm, start) == attrs; + + guard(rcu)(); + if (!attrs) + return !xas_find(&xas, end - 1); - has_attrs = true; for (index = start; index < end; index++) { do { entry = xas_next(&xas); } while (xas_retry(&xas, entry)); - if (xas.xa_index != index || xa_to_value(entry) != attrs) { - has_attrs = false; - break; - } + if (xas.xa_index != index || xa_to_value(entry) != attrs) + return false; } -out: - rcu_read_unlock(); - return has_attrs; -} - -static u64 kvm_supported_mem_attributes(struct kvm *kvm) -{ - if (!kvm || kvm_arch_has_private_mem(kvm)) - return KVM_MEMORY_ATTRIBUTE_PRIVATE; - - return 0; + return true; } static __always_inline void kvm_handle_gfn_range(struct kvm *kvm,
Use a guard to simplify early returns, and add two more easy shortcuts. If the requested attributes are invalid, the attributes xarray will never show them as set. And if testing a single page, kvm_get_memory_attributes() is more efficient. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> --- virt/kvm/kvm_main.c | 42 ++++++++++++++++++++---------------------- 1 file changed, 20 insertions(+), 22 deletions(-)