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pc_sysfw: allow flash (-pflash) memory to be used with KVM

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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
KVM_CAP_READONLY_MEM, 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.justen@intel.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 1369816047-16384-5-git-send-email-jordan.l.justen@intel.com
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This commit is contained in:
Jordan Justen 2013-05-29 01:27:27 -07:00 committed by Anthony Liguori
parent 235e8982ad
commit dafb82e0fc
1 changed files with 31 additions and 19 deletions
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50
hw/block/pc_sysfw.c
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@ -220,30 +220,42 @@ void pc_system_firmware_init(MemoryRegion *rom_memory)
qdev_init_nofail(DEVICE(sysfw_dev));
pflash_drv = drive_get(IF_PFLASH, 0, 0);
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, sysfw_dev->isapc_ram_fw);
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. Let's fix it for real in QEMU 1.6.
*/
if (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, sysfw_dev->isapc_ram_fw);
return;
}
}
/* If a pflash drive is not found, then create one using
the bios filename. */
if (pflash_drv == NULL) {