From: Avi Kivity <a...@redhat.com>
While not required by the spec, some guests (Linux)
rely on nmi being blocked by an IF-enabling sti. Add
a unit test for this condition.
Signed-off-by: Avi Kivity <a...@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosa...@redhat.com>
diff --git a/x86/apic.c b/x86/apic.c
index 165f820..2207040 100644
--- a/x86/apic.c
+++ b/x86/apic.c
@@ -1,6 +1,7 @@
#include "libcflat.h"
#include "apic.h"
#include "vm.h"
+#include "smp.h"
typedef struct {
unsigned short offset0;
@@ -274,9 +275,74 @@ static void test_ioapic_simultaneous(void)
g_66 && g_78 && g_66_after_78 && g_66_rip == g_78_rip);
}
+volatile int nmi_counter_private, nmi_counter, nmi_hlt_counter,
sti_loop_active;
+
+void sti_nop(char *p)
+{
+ asm volatile (
+ ".globl post_sti \n\t"
+ "sti \n"
+ /*
+ * vmx won't exit on external interrupt if blocked-by-sti,
+ * so give it a reason to exit by accessing an unmapped page.
+ */
+ "post_sti: testb $0, %0 \n\t"
+ "nop \n\t"
+ "cli"
+ : : "m"(*p)
+ );
+ nmi_counter = nmi_counter_private;
+}
+
+static void sti_loop(void *ignore)
+{
+ unsigned k = 0;
+
+ while (sti_loop_active) {
+ sti_nop((char *)(ulong)((k++ * 4096) % (128 * 1024 * 1024)));
+ }
+}
+
+static void nmi_handler(isr_regs_t *regs)
+{
+ extern void post_sti(void);
+ ++nmi_counter_private;
+ nmi_hlt_counter += regs->rip == (ulong)post_sti;
+}
+
+static void update_cr3(void *cr3)
+{
+ write_cr3((ulong)cr3);
+}
+
+static void test_sti_nmi(void)
+{
+ unsigned old_counter;
+
+ if (cpu_count() < 2) {
+ return;
+ }
+
+ set_idt_entry(2, nmi_handler);
+ on_cpu(1, update_cr3, (void *)read_cr3());
+
+ sti_loop_active = 1;
+ on_cpu_async(1, sti_loop, 0);
+ while (nmi_counter < 30000) {
+ old_counter = nmi_counter;
+ apic_icr_write(APIC_DEST_PHYSICAL | APIC_DM_NMI | APIC_INT_ASSERT, 1);
+ while (nmi_counter == old_counter) {
+ ;
+ }
+ }
+ sti_loop_active = 0;
+ report("nmi-after-sti", nmi_hlt_counter == 0);
+}
+
int main()
{
setup_vm();
+ smp_init();
test_lapic_existence();
@@ -288,6 +354,7 @@ int main()
test_ioapic_intr();
test_ioapic_simultaneous();
+ test_sti_nmi();
printf("\nsummary: %d tests, %d failures\n", g_tests, g_fail);
--
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