[PATCH kvm-unit-tests 2/2] VMX: Add test for interrupt acknowledgement

[Bandan Das <bsd@redhat.com>]

If the hypervisor has the interrupt acknowledgement bit set,
vector information is already present in intr_info during a vmexit.
The hypervisor then uses it to call the appropriate handler.

Signed-off-by: Bandan Das <bsd@redhat.com>
---
 lib/x86/isr.c   | 32 ++++++++++++++++++++++++++++++++
 lib/x86/isr.h   |  2 +-
 x86/vmx_tests.c | 26 +++++++++++++++++++++++---
 3 files changed, 56 insertions(+), 4 deletions(-)

diff --git a/lib/x86/isr.c b/lib/x86/isr.c
index 7dcd38a..b0c6f53 100644
--- a/lib/x86/isr.c
+++ b/lib/x86/isr.c
@@ -90,3 +90,35 @@ void handle_irq(unsigned vec, void (*func)(isr_regs_t *regs))
     *(u32 *)thunk = (ulong)isr_entry_point - (ulong)(thunk + 4);
 #endif
 }
+
+void handle_external_interrupt(int vector)
+{
+#ifdef __x86_64__
+	unsigned long tmp;
+#endif
+	idt_entry_t *idt = &boot_idt[vector];
+	unsigned long entry =
+	    idt->offset0 | ((unsigned long)idt->offset1 << 16) |
+	    ((unsigned long)idt->offset2 << 32);
+
+	asm volatile(
+#ifdef __x86_64__
+		     "mov %%rsp, %[sp]\n\t"
+		     "and $0xfffffffffffffff0, %%rsp\n\t"
+		     "push $%c[ss]\n\t"
+		     "push %[sp]\n\t"
+#endif
+		     "pushf\n\t"
+		     "orl $0x200, (%%rsp)\n\t"
+		     "push $%c[cs]\n\t"
+		     "call *%[entry]\n\t"
+		     :
+#ifdef __x86_64__
+		     [sp]"=&r"(tmp)
+#endif
+		     :
+		     [entry]"r"(entry),
+		     [ss]"i"(KERNEL_DS),
+		     [cs]"i"(KERNEL_CS)
+		     );
+}
diff --git a/lib/x86/isr.h b/lib/x86/isr.h
index b07a32a..a509291 100644
--- a/lib/x86/isr.h
+++ b/lib/x86/isr.h
@@ -10,5 +10,5 @@ typedef struct {
 } isr_regs_t;
 
 void handle_irq(unsigned vec, void (*func)(isr_regs_t *regs));
-
+void handle_external_interrupt(int vector);
 #endif
diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c
index 324f074..a40cb18 100644
--- a/x86/vmx_tests.c
+++ b/x86/vmx_tests.c
@@ -1290,6 +1290,16 @@ static void interrupt_main(void)
 
 	report("intercepted interrupt + activity state hlt",
 	       rdtsc() - start > 10000 && timer_fired);
+
+	apic_write(APIC_TMICT, 0);
+	irq_disable();
+	set_stage(7);
+	vmcall();
+	timer_fired = false;
+	apic_write(APIC_TMICT, 1);
+	for (loops = 0; loops < 10000000 && !timer_fired; loops++)
+		asm volatile ("nop");
+	report("running a guest with interrupt acknowledgement set", timer_fired);
 }
 
 static int interrupt_exit_handler(void)
@@ -1307,6 +1317,11 @@ static int interrupt_exit_handler(void)
 			vmcs_write(PIN_CONTROLS,
 				   vmcs_read(PIN_CONTROLS) | PIN_EXTINT);
 			break;
+		case 7:
+			vmcs_write(EXI_CONTROLS, vmcs_read(EXI_CONTROLS) | EXI_INTA);
+			vmcs_write(PIN_CONTROLS,
+				   vmcs_read(PIN_CONTROLS) | PIN_EXTINT);
+			break;
 		case 1:
 		case 3:
 			vmcs_write(PIN_CONTROLS,
@@ -1321,9 +1336,14 @@ static int interrupt_exit_handler(void)
 		vmcs_write(GUEST_RIP, guest_rip + insn_len);
 		return VMX_TEST_RESUME;
 	case VMX_EXTINT:
-		irq_enable();
-		asm volatile ("nop");
-		irq_disable();
+		if (vmcs_read(EXI_CONTROLS) & EXI_INTA) {
+			int vector = vmcs_read(EXI_INTR_INFO) & 0xff;
+			handle_external_interrupt(vector);
+		} else {
+			irq_enable();
+			asm volatile ("nop");
+			irq_disable();
+		}
 		if (get_stage() >= 2) {
 			vmcs_write(GUEST_ACTV_STATE, ACTV_ACTIVE);
 			vmcs_write(GUEST_RIP, guest_rip + insn_len);
-- 
1.8.3.1