From e300614f10bd2f33252c8ba40b34d6c3fbf95d72 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Thu, 11 Jul 2024 18:27:53 -0400 Subject: [PATCH] KVM: cleanup and add shortcuts to kvm_range_has_memory_attributes() 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. Reviewed-by: Michael Roth Signed-off-by: Paolo Bonzini --- 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 d0788d0a72cc..30328ff2d840 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2398,6 +2398,14 @@ 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. @@ -2406,40 +2414,30 @@ 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,