When a vCPU is running in Root mode and a notification event
has been injected to it. we need to set VCPU_KICK_SOFTIRQ for
the current cpu, so the pending interrupt in PIRR will be
synced to vIRR before VM-Exit in time.
Signed-off-by: Feng Wu <feng...@intel.com>
---
v3:
- Make pi_notification_interrupt() static
xen/arch/x86/hvm/vmx/vmx.c | 55 +++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 54 insertions(+), 1 deletion(-)
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index 7db6009..5795afd 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -1896,6 +1896,59 @@ static void pi_wakeup_interrupt(struct cpu_user_regs
*regs)
this_cpu(irq_count)++;
}
+/*
+ * Handle VT-d posted-interrupt when VCPU is running.
+ */
+
+static void pi_notification_interrupt(struct cpu_user_regs *regs)
+{
+ /*
+ * We get here when a vCPU is running in root-mode
+ * (such as via hypercall, or any other reasons which
+ * can result in VM-Exit), and before vCPU is back to
+ * non-root, external interrupts from an assigned
+ * device happen and a notification event is delivered
+ * to this logical CPU.
+ *
+ * we need to set VCPU_KICK_SOFTIRQ for the current
+ * cpu, just like __vmx_deliver_posted_interrupt().
+ *
+ * So the pending interrupt in PIRR will be synced to
+ * vIRR before VM-Exit in time.
+ *
+ * Please refer to the following code fragments from
+ * xen/arch/x86/hvm/vmx/entry.S:
+ *
+ * .Lvmx_do_vmentry
+ *
+ * ......
+ * point 1
+ *
+ * cmp %ecx,(%rdx,%rax,1)
+ * jnz .Lvmx_process_softirqs
+ *
+ * ......
+ *
+ * je .Lvmx_launch
+ *
+ * ......
+ *
+ * .Lvmx_process_softirqs:
+ * sti
+ * call do_softirq
+ * jmp .Lvmx_do_vmentry
+ *
+ * If VT-d engine issues a notification event at
+ * point 1 above, it cannot be delivered to the guest
+ * during this VM-entry without raising the softirq
+ * in this notification handler.
+ */
+ raise_softirq(VCPU_KICK_SOFTIRQ);
+
+ ack_APIC_irq();
+ this_cpu(irq_count)++;
+}
+
const struct hvm_function_table * __init start_vmx(void)
{
set_in_cr4(X86_CR4_VMXE);
@@ -1933,7 +1986,7 @@ const struct hvm_function_table * __init start_vmx(void)
if ( cpu_has_vmx_posted_intr_processing )
{
- alloc_direct_apic_vector(&posted_intr_vector, event_check_interrupt);
+ alloc_direct_apic_vector(&posted_intr_vector,
pi_notification_interrupt);
if ( iommu_intpost )
alloc_direct_apic_vector(&pi_wakeup_vector, pi_wakeup_interrupt);
--
2.1.0
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