When pc-sysfw.rom_only != 0, flash memory will be
usable with kvm. In order to enable flash memory mode,
a pflash device must be created. (For example, by
using the -pflash command line parameter.)
Usage of a flash memory device with kvm requires the
KVM READONLY memory capability, and kvm will abort if
a flash device is used with an older kvm which does
not support this capability.
If a flash device is not used, then qemu/kvm will
operate in the original rom-mode.
Signed-off-by: Jordan Justen <jordan.l.jus...@intel.com>
---
hw/block/pc_sysfw.c | 50 +++++++++++++++++++++++++++++++-------------------
1 file changed, 31 insertions(+), 19 deletions(-)
diff --git a/hw/block/pc_sysfw.c b/hw/block/pc_sysfw.c
index aad8614..301eb96 100644
--- a/hw/block/pc_sysfw.c
+++ b/hw/block/pc_sysfw.c
@@ -215,28 +215,40 @@ void pc_system_firmware_init(MemoryRegion *rom_memory)
qdev_init_nofail(DEVICE(sysfw_dev));
- if (sysfw_dev->rom_only) {
- old_pc_system_rom_init(rom_memory);
- return;
- }
-
pflash_drv = drive_get(IF_PFLASH, 0, 0);
- /* Currently KVM cannot execute from device memory.
- Use old rom based firmware initialization for KVM. */
- /*
- * This is a Bad Idea, because it makes enabling/disabling KVM
- * guest-visible. Do it only in bug-compatibility mode.
- */
- if (pc_sysfw_flash_vs_rom_bug_compatible && kvm_enabled()) {
- if (pflash_drv != NULL) {
- fprintf(stderr, "qemu: pflash cannot be used with kvm enabled\n");
- exit(1);
- } else {
- sysfw_dev->rom_only = 1;
- old_pc_system_rom_init(rom_memory);
- return;
+ if (pc_sysfw_flash_vs_rom_bug_compatible) {
+ /*
+ * This is a Bad Idea, because it makes enabling/disabling KVM
+ * guest-visible. Do it only in bug-compatibility mode.
+ */
+ if (kvm_enabled()) {
+ if (pflash_drv != NULL) {
+ fprintf(stderr, "qemu: pflash cannot be used with kvm
enabled\n");
+ exit(1);
+ } else {
+ /* In old pc_sysfw_flash_vs_rom_bug_compatible mode, we assume
+ * that KVM cannot execute from device memory. In this case, we
+ * use old rom based firmware initialization for KVM. But,
since
+ * this is different from non-kvm mode, this behavior is
+ * undesirable */
+ sysfw_dev->rom_only = 1;
+ }
}
+ } else if (pflash_drv == NULL) {
+ /* When a pflash drive is not found, use rom-mode */
+ sysfw_dev->rom_only = 1;
+ } else if (kvm_enabled() && !kvm_readonly_mem_enabled()) {
+ /* Older KVM cannot execute from device memory. So, flash memory
+ * cannot be used unless the readonly memory kvm capability is
present. */
+ fprintf(stderr, "qemu: pflash with kvm requires KVM readonly memory
support\n");
+ exit(1);
+ }
+
+ /* If rom-mode is active, use the old pc system rom initialization. */
+ if (sysfw_dev->rom_only) {
+ old_pc_system_rom_init(rom_memory);
+ return;
}
/* If a pflash drive is not found, then create one using
--
1.7.10.4
