pvh: add benchmark exit point
This commit adds a PVH specific VM exit point for use in benchmarking
boot times using a QEMU specific device that terminates the QEMU process
and thus the VM itself when handling those VM exits. Since the VM
terminates right at those exit points, generic tools like time can
be used to measure the time spent between the QEMU startup
and termination moments.
The QEMU device used for those measurement is called isa-debug-exit
for the PC and Q35 machine types. These devices take 2 arguments:
iobase and iosize. iobase specifies which IO port we need to write
into to have these devices eventually handle the corresponding VM exit.
If for example, QEMU is started with the following argument:
-device isa-debug-exit,iobase=0xf4
then any IO write to 0xf4 will terminate the QEMU process and the
corresponding VM.
Signed-off-by: Liam Merwick <liam.merwick@oracle.com>
diff --git a/benchmark.h b/benchmark.h
index 089c549..2be08e7 100644
--- a/benchmark.h
+++ b/benchmark.h
@@ -9,5 +9,6 @@
#define FW_START 1
#define LINUX_START_FWCFG 2
#define LINUX_START_BOOT 3
+#define LINUX_START_PVHBOOT 4
-#endif
+#endif /* BENCHMARK_H */
diff --git a/fw_cfg.c b/fw_cfg.c
index 09bb0d3..9304fd0 100644
--- a/fw_cfg.c
+++ b/fw_cfg.c
@@ -243,6 +243,12 @@
fw_cfg_select(FW_CFG_KERNEL_ENTRY);
kernel_entry = (void *) fw_cfg_readl_le();
+#ifdef BENCHMARK_HACK
+ /* Exit just before jumping to vmlinux, so that it is easy
+ * to time/profile the firmware.
+ */
+ outb(LINUX_EXIT_PORT, LINUX_START_PVHBOOT);
+#endif
asm volatile("jmp *%2" : : "a" (0x2badb002),
"b"(&start_info), "c"(kernel_entry));
panic();
