KVM: x86: Replace cpu_dirty_logging_count with nr_memslots_dirty_logging

Drop cpu_dirty_logging_count in favor of nr_memslots_dirty_logging.
Both fields count the number of memslots that have dirty-logging enabled,
with the only difference being that cpu_dirty_logging_count is only
incremented when using PML. So while nr_memslots_dirty_logging is not a
direct replacement for cpu_dirty_logging_count, it can be combined with
enable_pml to get the same information.

Signed-off-by: David Matlack <dmatlack@google.com>
Link: https://lore.kernel.org/r/20230105214303.2919415-1-dmatlack@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 4d2bc08..960f88c 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1327,7 +1327,6 @@ struct kvm_arch {
        u32 bsp_vcpu_id;
 
        u64 disabled_quirks;
-       int cpu_dirty_logging_count;
 
        enum kvm_irqchip_mode irqchip_mode;
        u8 nr_reserved_ioapic_pins;

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index c788aa3..bbf60bd 100644 (file)
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -4606,7 +4606,7 @@ static u32 vmx_secondary_exec_control(struct vcpu_vmx *vmx)
         * it needs to be set here when dirty logging is already active, e.g.
         * if this vCPU was created after dirty logging was enabled.
         */
-       if (!vcpu->kvm->arch.cpu_dirty_logging_count)
+       if (!enable_pml || !atomic_read(&vcpu->kvm->nr_memslots_dirty_logging))
                exec_control &= ~SECONDARY_EXEC_ENABLE_PML;
 
        if (cpu_has_vmx_xsaves()) {
@@ -7988,17 +7988,20 @@ void vmx_update_cpu_dirty_logging(struct kvm_vcpu *vcpu)
 {
        struct vcpu_vmx *vmx = to_vmx(vcpu);
 
+       if (WARN_ON_ONCE(!enable_pml))
+               return;
+
        if (is_guest_mode(vcpu)) {
                vmx->nested.update_vmcs01_cpu_dirty_logging = true;
                return;
        }
 
        /*
-        * Note, cpu_dirty_logging_count can be changed concurrent with this
+        * Note, nr_memslots_dirty_logging can be changed concurrent with this
         * code, but in that case another update request will be made and so
         * the guest will never run with a stale PML value.
         */
-       if (vcpu->kvm->arch.cpu_dirty_logging_count)
+       if (atomic_read(&vcpu->kvm->nr_memslots_dirty_logging))
                secondary_exec_controls_setbit(vmx, SECONDARY_EXEC_ENABLE_PML);
        else
                secondary_exec_controls_clearbit(vmx, SECONDARY_EXEC_ENABLE_PML);

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 508074e..fc3ae3c 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -12488,16 +12488,14 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
 
 static void kvm_mmu_update_cpu_dirty_logging(struct kvm *kvm, bool enable)
 {
-       struct kvm_arch *ka = &kvm->arch;
+       int nr_slots;
 
        if (!kvm_x86_ops.cpu_dirty_log_size)
                return;
 
-       if ((enable && ++ka->cpu_dirty_logging_count == 1) ||
-           (!enable && --ka->cpu_dirty_logging_count == 0))
+       nr_slots = atomic_read(&kvm->nr_memslots_dirty_logging);
+       if ((enable && nr_slots == 1) || !nr_slots)
                kvm_make_all_cpus_request(kvm, KVM_REQ_UPDATE_CPU_DIRTY_LOGGING);
-
-       WARN_ON_ONCE(ka->cpu_dirty_logging_count < 0);
 }
 
 static void kvm_mmu_slot_apply_flags(struct kvm *kvm,