diff mbox series

[v2] KVM: x86: Replace cpu_dirty_logging_count with nr_memslots_dirty_logging

Message ID 20230105214303.2919415-1-dmatlack@google.com (mailing list archive)
State New, archived
Headers show
Series [v2] KVM: x86: Replace cpu_dirty_logging_count with nr_memslots_dirty_logging | expand

Commit Message

David Matlack Jan. 5, 2023, 9:43 p.m. UTC 
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>
---
v2:
 - Return early if !enable_pml in vmx_update_cpu_dirty_logging() [Sean]
 - Do a single atomic_read() in kvm_mmu_update_cpu_dirty_logging() [Sean]

v1: https://lore.kernel.org/kvm/20230105165431.2770276-1-dmatlack@google.com/

 arch/x86/include/asm/kvm_host.h | 1 -
 arch/x86/kvm/vmx/vmx.c          | 9 ++++++---
 arch/x86/kvm/x86.c              | 8 +++-----
 3 files changed, 9 insertions(+), 9 deletions(-)


base-commit: 91dc252b0dbb6879e4067f614df1e397fec532a1

Comments

Sean Christopherson Jan. 19, 2023, 8:48 p.m. UTC | #1 
On Thu, 05 Jan 2023 13:43:03 -0800, David Matlack wrote:
> 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.
> 
> [...]

Applied to kvm-x86 misc, thanks!

[1/1] KVM: x86: Replace cpu_dirty_logging_count with nr_memslots_dirty_logging
      https://github.com/kvm-x86/linux/commit/1799eb69b994

--
https://github.com/kvm-x86/linux/tree/next
https://github.com/kvm-x86/linux/tree/fixes
diff mbox series

Patch

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 2f5bf581d00a..f328007ea05a 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1329,7 +1329,6 @@  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 c788aa382611..bbf60bda877e 100644
--- 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 c936f8d28a53..2f273b20fcdf 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -12482,16 +12482,14 @@  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,