Commit dafb82e0 authored by Jordan Justen's avatar Jordan Justen Committed by Anthony Liguori
Browse files

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



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: default avatarJordan Justen <jordan.l.justen@intel.com>
Reviewed-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Message-id: 1369816047-16384-5-git-send-email-jordan.l.justen@intel.com
Signed-off-by: default avatarAnthony Liguori <aliguori@us.ibm.com>
parent 235e8982

hw/block/pc_sysfw.c

+31 −19
Original line number Diff line number Diff line
@@ -220,29 +220,41 @@ 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, 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. */

    if (pc_sysfw_flash_vs_rom_bug_compatible) {

        /*

         * This is a Bad Idea, because it makes enabling/disabling KVM

     * guest-visible.  Let's fix it for real in QEMU 1.6.

         * 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;

    }

    }



    /* If a pflash drive is not found, then create one using

       the bios filename. */