Why fully-virtualized Red Hat Enterprise Linux 5.5 guests running on AMD Opteron 6000-series based hosts panic on boot ?

Issue

• Why fully-virtualized Red Hat Enterprise Linux 5.5 guests running on AMD Opteron 6000-series based hosts panic on boot with the followiing error messages?

    Unable to handle kernel NULL pointer dereference at 0000000000000040 RIP:
    [<ffffffff8008192f>] cpuid4_cache_lookup+0x256/0x356
    PGD 0
    Oops: 0000 [1] SMP
    last sysfs file:
    CPU 0
    Modules linked in:
    Pid: 1, comm: swapper Not tainted 2.6.18-194.el5 #1
    RIP: 0010:[<ffffffff8008192f>]  [<ffffffff8008192f>] cpuid4_cache_lookup+0x256/6
    RSP: 0000:ffff81010fc75d60  EFLAGS: 00010246
    RAX: 0000000000000000 RBX: 0000000000000060 RCX: 00000000000006aa
    RDX: 0000000000000000 RSI: 0000000000000060 RDI: 0000000000000003
    RBP: ffff81010f765580 R08: 0000000000000001 R09: 0000000000000040
    R10: ffff81010fc75cf0 R11: 0000000000000060 R12: 0000000000000080
    R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000003
    FS:  0000000000000000(0000) GS:ffffffff803cb000(0000) knlGS:0000000000000000
    CS:  0010 DS: 0018 ES: 0018 CR0: 000000008005003b
    CR2: 0000000000000040 CR3: 0000000000201000 CR4: 00000000000006e0
    Process swapper (pid: 1, threadinfo ffff81010fc74000, task ffff81010fc657a0)
    Stack:  ffff81010fc75e00 000280000f765ec0 0000000000000000 0000000000000000
    0000000040020140 00000000000000d0 ffff810140020140 0000000000000286
    00000000000006a9 0000000000000000 0000000017c0003f 0000000000000000
    Call Trace:
    [<ffffffff80081c48>] cacheinfo_cpu_callback+0xe9/0x516
    [<ffffffff80081c93>] cacheinfo_cpu_callback+0x134/0x516
    [<ffffffff800820ae>] cache_sysfs_init+0x39/0x54
    [<ffffffff80407a5c>] init+0x1f9/0x2f7
    [<ffffffff8005efb1>] child_rip+0xa/0x11
    [<ffffffff801824cc>] acpi_ds_init_one_object+0x0/0x80
    [<ffffffff80407863>] init+0x0/0x2f7
    [<ffffffff8005efa7>] child_rip+0x0/0x11

    Code: 8b 72 40 48 8d 4c 24 1c 48 8b 7a 20 ba c4 01 00 00 e8 5f 77
    RIP  [<ffffffff8008192f>] cpuid4_cache_lookup+0x256/0x356
    RSP <ffff81010fc75d60>
    CR2: 0000000000000040
    <0>Kernel panic - not syncing: Fatal exception