Re: [PATCH 3.17 100/141] x86, microcode: Fix accessing dis_ucode_ldr on 32-bit

From: Boris Ostrovsky
Date: Tue Nov 25 2014 - 13:52:47 EST

On 11/25/2014 01:43 PM, Borislav Petkov wrote:
On Tue, Nov 25, 2014 at 01:43:26PM -0500, Boris Ostrovsky wrote:
I don't think this routine is called on PV.
They're either both called or none is. At least on baremetal, that is.


PV guests don't start with startup_32.

We are coming from a resume into load_ucode_ap as:

[ 38.644599] BUG: unable to handle kernel paging request at 0197eec0
[ 38.644599] IP: [<c1071fa6>] load_ucode_ap+0x6/0xe0
[ 38.644599] *pdpt = 0000000003267007 *pde = 0000000000000000
[ 38.644599] Oops: 0000 [#1] SMP
[ 38.644599] Modules linked in: sg sd_mod dm_multipath dm_mod xen_evtchn iscsi_boot_sysfs iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi scsi_mod libcrc32c crc32c_generic radeon fbcon tileblit font bitblit ttm softcursor drm_kms_helper x86_pkg_temp_thermal crc32c_intel xen_blkfront xen_netfront xen_fbfront fb_sys_fops sysimgblt sysfillrect syscopyarea xen_kbdfront xenfs xen_privcmd
[ 38.644599] CPU: 0 PID: 9 Comm: migration/0 Tainted: G W 3.18.0-rc6upstream-00001-g0de9524 #1
[ 38.644599] task: eb894650 ti: eb89c000 task.ti: eb89c000
[ 38.644599] EIP: 0061:[<c1071fa6>] EFLAGS: 00010082 CPU: 0
[ 38.644599] EIP is at load_ucode_ap+0x6/0xe0
[ 38.644599] EAX: 00000000 EBX: c1823160 ECX: 00000000 EDX: c197eee0
[ 38.644599] ESI: eb9bded0 EDI: c1793e95 EBP: eb89de28 ESP: eb89de20
[ 38.644599] DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0069
[ 38.644599] CR0: 80050033 CR2: 0197eec0 CR3: 03280000 CR4: 00042660
[ 38.644599] Stack:
[ 38.644599] eb89de30 c10539b0 eb89de30 c1070f9d eb89de54 c140de9e eb9bded0 eb89de54
[ 38.644599] c103dbcc 00000008 deadbeef eb9bded0 eb9bdee4 eb89de80 c1397f57 00000000
[ 38.644599] 00000000 80000002 eb9bdf1c 00000000 00000002 00000003 eb9bded0 eb9bdee4
[ 38.644599] Call Trace:
[ 38.644599] [<c10539b0>] ? i8237A_resume+0xb0/0xe0
[ 38.644599] [<c1070f9d>] mc_bp_resume+0x3d/0x50
[ 38.644599] [<c140de9e>] syscore_resume+0x4e/0x190
[ 38.644599] [<c103dbcc>] ? xen_timer_resume+0x3c/0x60
[ 38.644599] [<c1397f57>] xen_suspend+0x77/0xf0
[ 38.644599] [<c110dc63>] multi_cpu_stop+0x93/0xc0
[ 38.644599] [<c110de76>] cpu_stopper_thread+0x46/0x170
[ 38.644599] [<c110dbd0>] ? irq_cpu_stop_queue_work+0x20/0x20
[ 38.644599] [<c162c536>] ? __schedule+0x356/0x880
[ 38.644599] [<c10b7aab>] ? default_wake_function+0xb/0x10
[ 38.644599] [<c10c7c00>] ? __wake_up_common+0x40/0x70
[ 38.644599] [<c1630730>] ? _raw_spin_unlock_irqrestore+0x20/0x90
[ 38.644599] [<c1630730>] ? _raw_spin_unlock_irqrestore+0x20/0x90
[ 38.644599] [<c16304ef>] ? _raw_spin_lock_irqsave+0x1f/0x80
[ 38.644599] [<c16306bf>] ? _raw_spin_lock_irq+0xf/0x60
[ 38.644599] [<c10aff47>] smpboot_thread_fn+0x117/0x1a0
[ 38.644599] [<c10ac824>] kthread+0xa4/0xc0
[ 38.644599] [<c10afe30>] ? smpboot_create_threads+0x60/0x60
[ 38.644599] [<c1630bc1>] ret_from_kernel_thread+0x21/0x30
[ 38.644599] [<c10ac780>] ? kthread_freezable_should_stop+0x60/0x60
[ 38.644599] Code: 55 cc eb 93 89 44 24 04 66 31 f6 c7 04 24 78 f0 74 c1 e8 84 9f 5b 00 eb ae 90 90 90 90 90 90 90 90 90 90 90 90 55 89 e5 83 ec 08 <80> 3d c0 ee 97 01 00 89 1c 24 89 74 24 04 74 12 8b 1c 24 8b 74
[ 38.644599] EIP: [<c1071fa6>] load_ucode_ap+0x6/0xe0 SS:ESP 0069:eb89de20
[ 38.644599] CR2: 000000000197eec0
[ 38.644599] ---[ end trace 0ad7358b42202518 ]---
[ 38.644599] Kernel panic - not syncing: Fatal exception
[ 38.644599] Kernel Offset: 0x0 from 0xc1000000 (relocation range: 0xc0000000-0xed7fdfff)




-boris
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