On Sun, Mar 24, 2013 at 07:44:45PM +0100, Jan Kiszka wrote:
> From: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
>
> The basic idea is to always transfer the pending event injection on
> vmexit into the architectural state of the VCPU and then drop it from
> there if it turns out that we left L2 to enter L1, i.e. if we enter
> prepare_vmcs12.
>
> vmcs12_save_pending_events takes care to transfer pending L0 events into
> the queue of L1. That is mandatory as L1 may decide to switch the guest
> state completely, invalidating or preserving the pending events for
> later injection (including on a different node, once we support
> migration).
>
> This concept is based on the rule that a pending vmlaunch/vmresume is
> not canceled. Otherwise, we would risk to lose injected events or leak
> them into the wrong queues. Encode this rule via a WARN_ON_ONCE at the
> entry of nested_vmx_vmexit.
>
> Signed-off-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
> ---
> arch/x86/kvm/vmx.c | 90 +++++++++++++++++++++++++++++++++------------------
> 1 files changed, 58 insertions(+), 32 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 8827b3b..9d9ff74 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -6493,8 +6493,6 @@ static void __vmx_complete_interrupts(struct kvm_vcpu *vcpu,
>
> static void vmx_complete_interrupts(struct vcpu_vmx *vmx)
> {
> - if (is_guest_mode(&vmx->vcpu))
> - return;
> __vmx_complete_interrupts(&vmx->vcpu, vmx->idt_vectoring_info,
> VM_EXIT_INSTRUCTION_LEN,
> IDT_VECTORING_ERROR_CODE);
> @@ -6502,8 +6500,6 @@ static void vmx_complete_interrupts(struct vcpu_vmx *vmx)
>
> static void vmx_cancel_injection(struct kvm_vcpu *vcpu)
> {
> - if (is_guest_mode(vcpu))
> - return;
> __vmx_complete_interrupts(vcpu,
> vmcs_read32(VM_ENTRY_INTR_INFO_FIELD),
> VM_ENTRY_INSTRUCTION_LEN,
> @@ -6535,21 +6531,6 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
> struct vcpu_vmx *vmx = to_vmx(vcpu);
> unsigned long debugctlmsr;
>
> - if (is_guest_mode(vcpu) && !vmx->nested.nested_run_pending) {
> - struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
> - if (vmcs12->idt_vectoring_info_field &
> - VECTORING_INFO_VALID_MASK) {
> - vmcs_write32(VM_ENTRY_INTR_INFO_FIELD,
> - vmcs12->idt_vectoring_info_field);
> - vmcs_write32(VM_ENTRY_INSTRUCTION_LEN,
> - vmcs12->vm_exit_instruction_len);
> - if (vmcs12->idt_vectoring_info_field &
> - VECTORING_INFO_DELIVER_CODE_MASK)
> - vmcs_write32(VM_ENTRY_EXCEPTION_ERROR_CODE,
> - vmcs12->idt_vectoring_error_code);
> - }
> - }
> -
> /* Record the guest's net vcpu time for enforced NMI injections. */
> if (unlikely(!cpu_has_virtual_nmis() && vmx->soft_vnmi_blocked))
> vmx->entry_time = ktime_get();
> @@ -6708,17 +6689,6 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
>
> vmx->idt_vectoring_info = vmcs_read32(IDT_VECTORING_INFO_FIELD);
>
> - if (is_guest_mode(vcpu)) {
> - struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
> - vmcs12->idt_vectoring_info_field = vmx->idt_vectoring_info;
> - if (vmx->idt_vectoring_info & VECTORING_INFO_VALID_MASK) {
> - vmcs12->idt_vectoring_error_code =
> - vmcs_read32(IDT_VECTORING_ERROR_CODE);
> - vmcs12->vm_exit_instruction_len =
> - vmcs_read32(VM_EXIT_INSTRUCTION_LEN);
> - }
> - }
> -
> vmx->loaded_vmcs->launched = 1;
>
> vmx->exit_reason = vmcs_read32(VM_EXIT_REASON);
> @@ -7325,6 +7295,48 @@ vmcs12_guest_cr4(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
> vcpu->arch.cr4_guest_owned_bits));
> }
>
> +static void vmcs12_save_pending_event(struct kvm_vcpu *vcpu,
> + struct vmcs12 *vmcs12)
> +{
> + u32 idt_vectoring;
> + unsigned int nr;
> +
> + if (vcpu->arch.exception.pending) {
> + nr = vcpu->arch.exception.nr;
> + idt_vectoring = nr | VECTORING_INFO_VALID_MASK;
> +
> + if (kvm_exception_is_soft(nr)) {
> + vmcs12->vm_exit_instruction_len =
> + vcpu->arch.event_exit_inst_len;
> + idt_vectoring |= INTR_TYPE_SOFT_EXCEPTION;
> + } else
> + idt_vectoring |= INTR_TYPE_HARD_EXCEPTION;
> +
> + if (vcpu->arch.exception.has_error_code) {
> + idt_vectoring |= VECTORING_INFO_DELIVER_CODE_MASK;
> + vmcs12->idt_vectoring_error_code =
> + vcpu->arch.exception.error_code;
> + }
> +
> + vmcs12->idt_vectoring_info_field = idt_vectoring;
> + } else if (vcpu->arch.nmi_pending) {
> + vmcs12->idt_vectoring_info_field =
> + INTR_TYPE_NMI_INTR | INTR_INFO_VALID_MASK | NMI_VECTOR;
> + } else if (vcpu->arch.interrupt.pending) {
> + nr = vcpu->arch.interrupt.nr;
> + idt_vectoring = nr | VECTORING_INFO_VALID_MASK;
> +
> + if (vcpu->arch.interrupt.soft) {
> + idt_vectoring |= INTR_TYPE_SOFT_INTR;
> + vmcs12->vm_entry_instruction_len =
> + vcpu->arch.event_exit_inst_len;
> + } else
> + idt_vectoring |= INTR_TYPE_EXT_INTR;
> +
> + vmcs12->idt_vectoring_info_field = idt_vectoring;
> + }
else
vmcs12->idt_vectoring_info_field = 0.
Also you can drop
vmcs12->idt_vectoring_info_field = to_vmx(vcpu)->idt_vectoring_info;
from prepare_vmcs12().
> +}
> +
> /*
> * prepare_vmcs12 is part of what we need to do when the nested L2 guest exits
> * and we want to prepare to run its L1 parent. L1 keeps a vmcs for L2 (vmcs12),
> @@ -7416,9 +7428,20 @@ static void prepare_vmcs12(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
> vmcs12->vm_exit_instruction_len = vmcs_read32(VM_EXIT_INSTRUCTION_LEN);
> vmcs12->vmx_instruction_info = vmcs_read32(VMX_INSTRUCTION_INFO);
>
> - /* clear vm-entry fields which are to be cleared on exit */
> if (!(vmcs12->vm_exit_reason & VMX_EXIT_REASONS_FAILED_VMENTRY))
> - vmcs12->vm_entry_intr_info_field &= ~INTR_INFO_VALID_MASK;
> + /*
> + * Transfer the event that L0 or L1 may wanted to inject into
> + * L2 to IDT_VECTORING_INFO_FIELD.
> + */
> + vmcs12_save_pending_event(vcpu, vmcs12);
> +
> + /*
> + * Drop what we picked up for L2 via vmx_complete_interrupts. It is
> + * preserved above and would only end up incorrectly in L1.
> + */
> + vcpu->arch.nmi_injected = false;
> + kvm_clear_exception_queue(vcpu);
> + kvm_clear_interrupt_queue(vcpu);
> }
>
> /*
> @@ -7518,6 +7541,9 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu)
> int cpu;
> struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
>
> + /* trying to cancel vmlaunch/vmresume is a bug */
> + WARN_ON_ONCE(vmx->nested.nested_run_pending);
> +
> leave_guest_mode(vcpu);
> prepare_vmcs12(vcpu, vmcs12);
>
> --
> 1.7.3.4
--
Gleb.
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