[patch 2/8] test: add pagefault exception handler

[Marcelo Tosatti <mtosatti@redhat.com>]

[-- Attachment #1: pf-vector --]
[-- Type: text/plain, Size: 2018 bytes --]

Which print cr2 and exits.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

Index: qemu-kvm/kvm/user/test/lib/x86/smp.c
===================================================================
--- qemu-kvm.orig/kvm/user/test/lib/x86/smp.c
+++ qemu-kvm/kvm/user/test/lib/x86/smp.c
@@ -5,6 +5,7 @@
 #include "fwcfg.h"
 
 #define IPI_VECTOR 0x20
+#define PF_VECTOR 0xe
 
 static struct spinlock ipi_lock;
 static void (*ipi_function)(void *data);
@@ -18,6 +19,20 @@ static __attribute__((used)) void ipi()
     ipi_done = 1;
 }
 
+unsigned long read_cr2()
+{
+    unsigned long cr2;
+
+    asm volatile ("mov %%cr2, %0" : "=r"(cr2));
+    return cr2;
+}
+
+static __attribute__((used)) void pf()
+{
+    printf("PF: %lx\n", read_cr2());
+    asm ("call exit");
+}
+
 asm (
      "ipi_entry: \n"
      "   call ipi \n"
@@ -28,21 +43,31 @@ asm (
 #endif
      );
 
+asm (
+     "pf_entry: \n"
+     "   call pf \n"
+#ifndef __x86_64__
+     "   iret"
+#else
+     "   iretq"
+#endif
+     );
+
 
-static void set_ipi_descriptor(void (*ipi_entry)(void))
+static void set_exp_descriptor(void (*entry)(void), unsigned vec)
 {
-    unsigned short *desc = (void *)(IPI_VECTOR * sizeof(long) * 2);
+    unsigned short *desc = (void *)(vec * sizeof(long) * 2);
     unsigned short cs;
-    unsigned long ipi = (unsigned long)ipi_entry;
+    unsigned long fn = (unsigned long)entry;
 
     asm ("mov %%cs, %0" : "=r"(cs));
-    desc[0] = ipi;
+    desc[0] = fn;
     desc[1] = cs;
     desc[2] = 0x8e00;
-    desc[3] = ipi >> 16;
+    desc[3] = fn >> 16;
 #ifdef __x86_64__
-    desc[4] = ipi >> 32;
-    desc[5] = ipi >> 48;
+    desc[4] = fn >> 32;
+    desc[5] = fn >> 48;
     desc[6] = 0;
     desc[7] = 0;
 #endif
@@ -118,8 +143,10 @@ void smp_init_ids(void)
 {
     int i;
     void ipi_entry(void);
+    void pf_entry(void);
 
-    set_ipi_descriptor(ipi_entry);
+    set_exp_descriptor(ipi_entry, IPI_VECTOR);
+    set_exp_descriptor(pf_entry, PF_VECTOR);
 
     setup_smp_id(0);
     for (i = 1; i < cpu_count(); ++i)