On Fri, Dec 12, 2014 at 11:14:57PM +0800, Feng Wu wrote:
> This patch updates the Posted-Interrupts Descriptor when vCPU
> is preempted.
>
> sched out:
> - Set 'SN' to suppress furture non-urgent interrupts posted for
> the vCPU.
What wakes the vcpu in the case of a non-urgent interrupt, then?
I wonder how is software suppose to configure the urgent/non-urgent
flag. Can you give examples of (hypothetical) urgent and non-urgent
interrupts.
> sched in:
> - Clear 'SN'
> - Change NDST if vCPU is scheduled to a different CPU
> - Set 'NV' to POSTED_INTR_VECTOR
What about:
POSTED_INTR_VECTOR interrupt handler:
- Wakeup vcpu.
- Set 'SN' to suppress future interrupts.
HLT emulation entry:
- Clear 'SN' to receive VT-d interrupt notification.
> Signed-off-by: Feng Wu <feng.wu@xxxxxxxxx>
> ---
> arch/x86/kvm/vmx.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 44 insertions(+)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index ee3b735..bf2e6cd 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -1916,10 +1916,54 @@ static void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
> vmcs_writel(HOST_IA32_SYSENTER_ESP, sysenter_esp); /* 22.2.3 */
> vmx->loaded_vmcs->cpu = cpu;
> }
> +
> + if (irq_remapping_cap(IRQ_POSTING_CAP)) {
> + struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu);
> + struct pi_desc old, new;
> + unsigned int dest;
> +
> + memset(&old, 0, sizeof(old));
> + memset(&new, 0, sizeof(new));
> +
> + do {
> + old.control = new.control = pi_desc->control;
> + if (vcpu->cpu != cpu) {
> + dest = cpu_physical_id(cpu);
> +
> + if (x2apic_enabled())
> + new.ndst = dest;
> + else
> + new.ndst = (dest << 8) & 0xFF00;
> + }
> +
> + pi_clear_sn(&new);
> +
> + /* set 'NV' to 'notification vector' */
> + new.nv = POSTED_INTR_VECTOR;
> + } while (cmpxchg(&pi_desc->control, old.control,
> + new.control) != old.control);
> + }
> }
>
> static void vmx_vcpu_put(struct kvm_vcpu *vcpu)
> {
> + if (irq_remapping_cap(IRQ_POSTING_CAP)) {
> + struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu);
> + struct pi_desc old, new;
> +
> + memset(&old, 0, sizeof(old));
> + memset(&new, 0, sizeof(new));
> +
> + /* Set SN when the vCPU is preempted */
> + if (vcpu->preempted) {
> + do {
> + old.control = new.control = pi_desc->control;
> + pi_set_sn(&new);
> + } while (cmpxchg(&pi_desc->control, old.control,
> + new.control) != old.control);
> + }
> + }
> +
> __vmx_load_host_state(to_vmx(vcpu));
> if (!vmm_exclusive) {
> __loaded_vmcs_clear(to_vmx(vcpu)->loaded_vmcs);
> --
> 1.9.1
>
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