runqemu: support UEFI with OVMF firmware

In the simplest case, "runqemu qemux86 <some-image> qcow2 ovmf" for an
EFI-enabled image in the qcow2 format will locate the ovmf.qcow2
firmware file deployed by the ovmf recipe in the image deploy
directory, override the graphics hardware with "-vga std" because that
is all that OVMF supports, and boot with UEFI enabled.

ovmf is not built by default. Either do it explicitly ("bitbake ovmf")
or make it a part of the normal build
("MACHINE_ESSENTIAL_EXTRA_RDEPENDS_append = ' ovmf'").

The firmware file is activated as a flash drive instead of using the
qemu BIOS parameters, because that is the recommended method
(https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=764918#47) as it
allows storing UEFI variables in the file.

Instead of just "ovmf", a full path to an existing file can also be
used, just as with the rootfs. That may be useful when making a
permanent copy of the virtual machine data files.

It is possible to specify "ovmf*" parameters more than once, then
each parameter creates a separate flash drive. This way it is possible
to use separate flash drives for firmware code and variables:
$ runqemu qemux86 <some-image> qcow2 ovmf.code ovmf.vars"

Note that rebuilding ovmf will overwrite the ovmf.vars.qcow2 file in
the image deploy directory. So when the goal is to update the firmware
while keeping variables, make a copy of the variable file and use
that:
$ mkdir my-machine
$ cp tmp/deploy/images/qemux86/ovmf.vars.qcow2 my-machine/
$ runqemu qemux86 <some-image> qcow2 ovmf.code my-machine/ovmf.vars.qcow2

When Secure Boot was enabled in ovmf, one can pick that instead of
the non-Secure-Boot enabled ovmf.code:
$ runqemu qemux86 <some-image> qcow2 ovmf.secboot.code my-machine/ovmf.vars.qcow2

(From OE-Core rev: b91fc0893651b9e3069893e36439de0b4e70ad13)

Signed-off-by: Patrick Ohly <patrick.ohly@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/runqemu

@@ -74,6 +74,7 @@ of the following environment variables (in any order):
     kvm-vhost - enable KVM with vhost when running x86/x86_64 (VT-capable CPU required)
     publicvnc - enable a VNC server open to all hosts
     audio - enable audio
+    [*/]ovmf* - OVMF firmware file or base name for booting with UEFI
   tcpserial=<port> - specify tcp serial port number
   biosdir=<dir> - specify custom bios dir
   biosfilename=<filename> - specify bios filename
@@ -175,6 +176,13 @@ class BaseConfig(object):
         self.clean_nfs_dir = False
         self.nfs_server = ''
         self.rootfs = ''
+        # File name(s) of a OVMF firmware file or variable store,
+        # to be added with -drive if=pflash.
+        # Found in the same places as the rootfs, with or without one of
+        # these suffices: qcow2, bin.
+        # Setting one also adds "-vga std" because that is all that
+        # OVMF supports.
+        self.ovmf_bios = []
         self.qemuboot = ''
         self.qbconfload = False
         self.kernel = ''
@@ -281,6 +289,7 @@ class BaseConfig(object):
         - Check whether is a kernel file
         - Check whether is a image file
         - Check whether it is a nfs dir
+        - Check whether it is a OVMF flash file
         """
         if p.endswith('.qemuboot.conf'):
             self.qemuboot = p
@@ -321,6 +330,8 @@ class BaseConfig(object):
             else:
                 logger.info("Assuming %s is an nfs rootfs" % p)
                 self.check_arg_nfs(p)
+        elif os.path.basename(p).startswith('ovmf'):
+            self.ovmf_bios.append(p)
         else:
             raise Exception("Unknown path arg %s" % p)
 
@@ -406,6 +417,8 @@ class BaseConfig(object):
             elif re.search(r'-image-|-image$', arg):
                 # Lazy rootfs
                 self.rootfs = arg
+            elif arg.startswith('ovmf'):
+                self.ovmf_bios.append(arg)
             else:
                 # At last, assume is it the MACHINE
                 if (not unknown_arg) or unknown_arg == arg:
@@ -504,6 +517,20 @@ class BaseConfig(object):
         if not os.path.exists(self.rootfs):
             raise Exception("Can't find rootfs: %s" % self.rootfs)
 
+    def check_ovmf(self):
+        """Check and set full path for OVMF firmware and variable file(s)."""
+
+        for index, ovmf in enumerate(self.ovmf_bios):
+            if os.path.exists(ovmf):
+                continue
+            for suffix in ('qcow2', 'bin'):
+                path = '%s/%s.%s' % (self.get('DEPLOY_DIR_IMAGE'), ovmf, suffix)
+                if os.path.exists(path):
+                    self.ovmf_bios[index] = path
+                    break
+            else:
+                raise Exception("Can't find OVMF firmware: %s" % ovmf)
+
     def check_kernel(self):
         """Check and set kernel, dtb"""
         # The vm image doesn't need a kernel
@@ -598,6 +625,7 @@ class BaseConfig(object):
         self.check_kvm()
         self.check_fstype()
         self.check_rootfs()
+        self.check_ovmf()
         self.check_kernel()
         self.check_biosdir()
         self.check_mem()
@@ -706,6 +734,8 @@ class BaseConfig(object):
             print('NFS_DIR: [%s]' % self.nfs_dir)
         else:
             print('ROOTFS: [%s]' % self.rootfs)
+        if self.ovmf_bios:
+            print('OVMF: %s' % self.ovmf_bios)
         print('CONFFILE: [%s]' % self.qemuboot)
         print('')
 
@@ -1012,7 +1042,17 @@ class BaseConfig(object):
 
         check_libgl(qemu_bin)
 
-        self.qemu_opt = "%s %s %s %s %s" % (qemu_bin, self.get('NETWORK_CMD'), self.get('ROOTFS_OPTIONS'), self.get('QB_OPT_APPEND'), self.qemu_opt_script)
+        self.qemu_opt = "%s %s %s %s" % (qemu_bin, self.get('NETWORK_CMD'), self.get('ROOTFS_OPTIONS'), self.get('QB_OPT_APPEND'))
+
+        for ovmf in self.ovmf_bios:
+            format = ovmf.rsplit('.', 1)[-1]
+            self.qemu_opt += ' -drive if=pflash,format=%s,file=%s' % (format, ovmf)
+        if self.ovmf_bios:
+            # OVMF only supports normal VGA, i.e. we need to override a -vga vmware
+            # that gets added for example for normal qemux86.
+            self.qemu_opt += ' -vga std'
+
+        self.qemu_opt += ' ' + self.qemu_opt_script
 
         if self.snapshot:
             self.qemu_opt += " -snapshot"