Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull more KVM updates from Paolo Bonzini:
 "x86 KVM changes:

   - The usual accuracy improvements for nested virtualization

   - The usual round of code cleanups from Sean

   - Added back optimizations that were prematurely removed in 5.2 (the
     bare minimum needed to fix the regression was in 5.3-rc8, here
     comes the rest)

   - Support for UMWAIT/UMONITOR/TPAUSE

   - Direct L2->L0 TLB flushing when L0 is Hyper-V and L1 is KVM

   - Tell Windows guests if SMT is disabled on the host

   - More accurate detection of vmexit cost

   - Revert a pvqspinlock pessimization"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (56 commits)
  KVM: nVMX: cleanup and fix host 64-bit mode checks
  KVM: vmx: fix build warnings in hv_enable_direct_tlbflush() on i386
  KVM: x86: Don't check kvm_rebooting in __kvm_handle_fault_on_reboot()
  KVM: x86: Drop ____kvm_handle_fault_on_reboot()
  KVM: VMX: Add error handling to VMREAD helper
  KVM: VMX: Optimize VMX instruction error and fault handling
  KVM: x86: Check kvm_rebooting in kvm_spurious_fault()
  KVM: selftests: fix ucall on x86
  Revert "locking/pvqspinlock: Don't wait if vCPU is preempted"
  kvm: nvmx: limit atomic switch MSRs
  kvm: svm: Intercept RDPRU
  kvm: x86: Add "significant index" flag to a few CPUID leaves
  KVM: x86/mmu: Skip invalid pages during zapping iff root_count is zero
  KVM: x86/mmu: Explicitly track only a single invalid mmu generation
  KVM: x86/mmu: Revert "KVM: x86/mmu: Remove is_obsolete() call"
  KVM: x86/mmu: Revert "Revert "KVM: MMU: reclaim the zapped-obsolete page first""
  KVM: x86/mmu: Revert "Revert "KVM: MMU: collapse TLB flushes when zap all pages""
  KVM: x86/mmu: Revert "Revert "KVM: MMU: zap pages in batch""
  KVM: x86/mmu: Revert "Revert "KVM: MMU: add tracepoint for kvm_mmu_invalidate_all_pages""
  KVM: x86/mmu: Revert "Revert "KVM: MMU: show mmu_valid_gen in shadow page related tracepoints""
  ...

1 files changed, 14 insertions, 14 deletions

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 8675458c2205..3a3a6854dcca 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -65,7 +65,9 @@
 #define APIC_BROADCAST			0xFF
 #define X2APIC_BROADCAST		0xFFFFFFFFul
 
-#define LAPIC_TIMER_ADVANCE_ADJUST_DONE 100
+static bool lapic_timer_advance_dynamic __read_mostly;
+#define LAPIC_TIMER_ADVANCE_ADJUST_MIN 100
+#define LAPIC_TIMER_ADVANCE_ADJUST_MAX 5000
 #define LAPIC_TIMER_ADVANCE_ADJUST_INIT 1000
 /* step-by-step approximation to mitigate fluctuation */
 #define LAPIC_TIMER_ADVANCE_ADJUST_STEP 8
@@ -1485,26 +1487,25 @@ static inline void adjust_lapic_timer_advance(struct kvm_vcpu *vcpu,
 	u32 timer_advance_ns = apic->lapic_timer.timer_advance_ns;
 	u64 ns;
 
+	/* Do not adjust for tiny fluctuations or large random spikes. */
+	if (abs(advance_expire_delta) > LAPIC_TIMER_ADVANCE_ADJUST_MAX ||
+	    abs(advance_expire_delta) < LAPIC_TIMER_ADVANCE_ADJUST_MIN)
+		return;
+
 	/* too early */
 	if (advance_expire_delta < 0) {
 		ns = -advance_expire_delta * 1000000ULL;
 		do_div(ns, vcpu->arch.virtual_tsc_khz);
-		timer_advance_ns -= min((u32)ns,
-			timer_advance_ns / LAPIC_TIMER_ADVANCE_ADJUST_STEP);
+		timer_advance_ns -= ns/LAPIC_TIMER_ADVANCE_ADJUST_STEP;
 	} else {
 	/* too late */
 		ns = advance_expire_delta * 1000000ULL;
 		do_div(ns, vcpu->arch.virtual_tsc_khz);
-		timer_advance_ns += min((u32)ns,
-			timer_advance_ns / LAPIC_TIMER_ADVANCE_ADJUST_STEP);
+		timer_advance_ns += ns/LAPIC_TIMER_ADVANCE_ADJUST_STEP;
 	}
 
-	if (abs(advance_expire_delta) < LAPIC_TIMER_ADVANCE_ADJUST_DONE)
-		apic->lapic_timer.timer_advance_adjust_done = true;
-	if (unlikely(timer_advance_ns > 5000)) {
+	if (unlikely(timer_advance_ns > LAPIC_TIMER_ADVANCE_ADJUST_MAX))
 		timer_advance_ns = LAPIC_TIMER_ADVANCE_ADJUST_INIT;
-		apic->lapic_timer.timer_advance_adjust_done = false;
-	}
 	apic->lapic_timer.timer_advance_ns = timer_advance_ns;
 }
 
@@ -1524,7 +1525,7 @@ static void __kvm_wait_lapic_expire(struct kvm_vcpu *vcpu)
 	if (guest_tsc < tsc_deadline)
 		__wait_lapic_expire(vcpu, tsc_deadline - guest_tsc);
 
-	if (unlikely(!apic->lapic_timer.timer_advance_adjust_done))
+	if (lapic_timer_advance_dynamic)
 		adjust_lapic_timer_advance(vcpu, apic->lapic_timer.advance_expire_delta);
 }
 
@@ -2302,13 +2303,12 @@ int kvm_create_lapic(struct kvm_vcpu *vcpu, int timer_advance_ns)
 	apic->lapic_timer.timer.function = apic_timer_fn;
 	if (timer_advance_ns == -1) {
 		apic->lapic_timer.timer_advance_ns = LAPIC_TIMER_ADVANCE_ADJUST_INIT;
-		apic->lapic_timer.timer_advance_adjust_done = false;
+		lapic_timer_advance_dynamic = true;
 	} else {
 		apic->lapic_timer.timer_advance_ns = timer_advance_ns;
-		apic->lapic_timer.timer_advance_adjust_done = true;
+		lapic_timer_advance_dynamic = false;
 	}
 
-
 	/*
 	 * APIC is created enabled. This will prevent kvm_lapic_set_base from
 	 * thinking that APIC state has changed.