KVM: nVMX: keep preemption timer enabled during L2 execution (9314006d) · Commits · 戴 / test

Because the vmcs12 preemption timer is emulated through a separate hrtimer, we can keep on using the preemption timer in the vmcs02 to emulare L1's TSC deadline timer. However, the corresponding bit in the pin-based execution control field must be kept consistent between vmcs01 and vmcs02. On vmentry we copy it into the vmcs02; on vmexit the preemption timer must be disabled in the vmcs01 if a preemption timer vmexit happened while in guest mode. The preemption timer value in the vmcs02 is set by vmx_vcpu_run, so it need not be considered in prepare_vmcs02. Cc: Yunhong Jiang <yunhong.jiang@intel.com> Cc: Haozhong Zhang <haozhong.zhang@intel.com> Tested-by:

Wanpeng Li <kernellwp@gmail.com> Signed-off-by:

Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/vmx.c

+13 −2

Original line number	Diff line number	Diff line
		@@ -9796,9 +9796,14 @@ static void prepare_vmcs02(struct kvm_vcpu vcpu, struct vmcs12 vmcs12)
		vmcs_write64(VMCS_LINK_POINTER, -1ull);

		exec_control = vmcs12->pin_based_vm_exec_control;

		/* Preemption timer setting is only taken from vmcs01. */
		exec_control &= ~PIN_BASED_VMX_PREEMPTION_TIMER;
		exec_control \|= vmcs_config.pin_based_exec_ctrl;
		if (vmx->hv_deadline_tsc == -1)
		exec_control &= ~PIN_BASED_VMX_PREEMPTION_TIMER;

		/* Posted interrupts setting is only taken from vmcs12. */
		if (nested_cpu_has_posted_intr(vmcs12)) {
		/*
		* Note that we use L0's vector here and in
		@@ -10727,8 +10732,14 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason,

		load_vmcs12_host_state(vcpu, vmcs12);

		/* Update TSC_OFFSET if TSC was changed while L2 ran */
		/* Update any VMCS fields that might have changed while L2 ran */
		vmcs_write64(TSC_OFFSET, vmx->nested.vmcs01_tsc_offset);
		if (vmx->hv_deadline_tsc == -1)
		vmcs_clear_bits(PIN_BASED_VM_EXEC_CONTROL,
		PIN_BASED_VMX_PREEMPTION_TIMER);
		else
		vmcs_set_bits(PIN_BASED_VM_EXEC_CONTROL,
		PIN_BASED_VMX_PREEMPTION_TIMER);

		/* This is needed for same reason as it was needed in prepare_vmcs02 */
		vmx->host_rsp = 0;

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