Re: [PATCH] x86/efi: update e820 about reserved EFI boot services data to fix kexec breakage

[Dave Young <dyoung@redhat.com>]

Hi Dan,
[snip]
> I reproduced some other panics with or without my fix about the efi boot
> mem,  but not 100% reproducible although high likely.  I'm using params
> below:
> efi_fake_mem=200M@5G:0x40000,300M@5600M:0x40000
> 
> I suspect efi_fake_mem needs more careful sanity checks about the memory
> user provided, but I'm not very familiar with the details though..
> 
> The issues I notices are two different ones:
> First one is a panic during booting:
> [    0.210239] mem auto-init: stack:off, heap alloc:off, heap free:off
> [    0.215983] BUG: kernel NULL pointer dereference, address: 0000000000000008
> [    0.216835] #PF: supervisor write access in kernel mode
> [    0.217384] #PF: error_code(0x0002) - not-present page
> [    0.217976] PGD 0 P4D 0 
> [    0.218248] Oops: 0002 [#1] SMP PTI
> [    0.218668] CPU: 0 PID: 0 Comm: swapper Not tainted 5.5.0-rc3+ #3
> [    0.219315] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
> [    0.220191] RIP: 0010:__free_pages_ok+0x2de/0x5c0
> [    0.220690] Code: 00 00 4b 8d 04 a4 48 c1 e5 04 48 c1 e0 08 48 89 c1 48 01 c5 4b 8d 04 c0 48 c1 e0 03 48 01 c5 48 01 c8 49 8b b4 2e c0 00 00 00 <48> 89 7e 08 48 89 73 08 48 89 53 10 48 89 3a 49 83 84 06 00 01 00
> [    0.222843] RSP: 0000:ffffffff97e03e60 EFLAGS: 00010002
> [    0.223400] RAX: 00000000000007d0 RBX: ffffda4d00050000 RCX: 0000000000000500
> [    0.224200] RDX: ffffa2a9bd3fe900 RSI: 0000000000000000 RDI: ffffda4d00050008
> [    0.224984] RBP: 0000000000000840 R08: 000000000000000a R09: 0000000000000400
> [    0.225825] R10: dead000000000100 R11: 0000000000000039 R12: 0000000000000001
> [    0.226793] R13: ffffa2a9bd3fe500 R14: ffffa2a9bd3fe000 R15: 000000000000000a
> [    0.227764] FS:  0000000000000000(0000) GS:ffffa2a9b7600000(0000) knlGS:0000000000000000
> [    0.228799] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [    0.229511] CR2: 0000000000000008 CR3: 00000001cf80a001 CR4: 00000000000606b0
> [    0.230323] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [    0.231399] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> [    0.232219] Call Trace:
> [    0.232524]  memblock_free_all+0x127/0x195
> [    0.233090]  mem_init+0x15/0x9d
> [    0.233450]  start_kernel+0x215/0x4e0
> [    0.233875]  ? load_ucode_bsp+0x3e/0x11b
> [    0.234325]  secondary_startup_64+0xa4/0xb0
> [    0.234833] Modules linked in:
> [    0.235197] CR2: 0000000000000008
> [    0.235610] random: get_random_bytes called from print_oops_end_marker+0x26/0x40 with crng_init=0
> [    0.237389] ---[ end trace 58f36740c65a5535 ]---
> [    0.238111] RIP: 0010:__free_pages_ok+0x2de/0x5c0
> [    0.238747] Code: 00 00 4b 8d 04 a4 48 c1 e5 04 48 c1 e0 08 48 89 c1 48 01 c5 4b 8d 04 c0 48 c1 e0 03 48 01 c5 48 01 c8 49 8b b4 2e c0 00 00 00 <48> 89 7e 08 48 89 73 08 48 89 53 10 48 89 3a 49 83 84 06 00 01 00
> [    0.241001] RSP: 0000:ffffffff97e03e60 EFLAGS: 00010002
> [    0.241618] RAX: 00000000000007d0 RBX: ffffda4d00050000 RCX: 0000000000000500
> [    0.242461] RDX: ffffa2a9bd3fe900 RSI: 0000000000000000 RDI: ffffda4d00050008
> [    0.243308] RBP: 0000000000000840 R08: 000000000000000a R09: 0000000000000400
> [    0.244161] R10: dead000000000100 R11: 0000000000000039 R12: 0000000000000001
> [    0.245093] R13: ffffa2a9bd3fe500 R14: ffffa2a9bd3fe000 R15: 000000000000000a
> [    0.245995] FS:  0000000000000000(0000) GS:ffffa2a9b7600000(0000) knlGS:0000000000000000
> [    0.246972] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [    0.247863] CR2: 0000000000000008 CR3: 00000001cf80a001 CR4: 00000000000606b0
> [    0.248950] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [    0.249978] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> [    0.250976] Kernel panic - not syncing: Attempted to kill the idle task!
> [    0.251915] Rebooting in 10 seconds..
> 
> The second one is when reading some files after login, eg. cat
> /proc/iomem:
> 
> [   51.732899] BUG: unable to handle page fault for address: 000000007cfa9028
> [   51.736351] #PF: supervisor read access in kernel mode
> [   51.737549] #PF: error_code(0x0000) - not-present page
> [   51.738645] PGD 0 P4D 0 
> [   51.738929] Oops: 0000 [#1] SMP PTI
> [   51.739290] CPU: 1 PID: 467 Comm: cat Not tainted 5.5.0-rc3+ #3
> [   51.740040] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
> [   51.741084] RIP: 0010:r_show+0x33/0xc0
> [   51.741591] Code: fd 41 54 55 53 48 8b 47 70 48 89 f3 48 8b 78 20 e8 c2 1f 1d 00 48 89 da 48 81 78 08 00 00 01 00 19 ed 31 c9 83 e5 fc 83 c5 08 <48> 8b 52 28 48 39 c2 74 73 83 c1 01 83 f9 05 75 ef 41 bc 0a 00 00
> [   51.743884] RSP: 0018:ffff9a983145be30 EFLAGS: 00010202
> [   51.744538] RAX: ffffffff94632c00 RBX: 000000007cfa9000 RCX: 0000000000000000
> [   51.745359] RDX: 000000007cfa9000 RSI: 000000007cfa9000 RDI: ffff9a9828138048
> [   51.746363] RBP: 0000000000000008 R08: 0000000000000039 R09: 0000000000000005
> [   51.750059] R10: ffff9a9834cde000 R11: ffff9a9934cdd032 R12: ffff9a9834c95700
> [   51.750917] R13: ffff9a982d25f800 R14: ffff9a982d25f828 R15: ffff9a982d25f840
> [   51.751759] FS:  00007ff33164f580(0000) GS:ffff9a9837680000(0000) knlGS:0000000000000000
> [   51.752678] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [   51.753336] CR2: 000000007cfa9028 CR3: 00000001f3eae001 CR4: 0000000000160ee0
> [   51.754172] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [   51.755076] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> [   51.756199] Call Trace:
> [   51.756653]  seq_read+0x2f7/0x410
> [   51.757284]  proc_reg_read+0x3c/0x60
> [   51.757752]  vfs_read+0x9d/0x120
> [   51.758247]  ksys_read+0x5f/0xe0
> [   51.758871]  do_syscall_64+0x6b/0x260
> [   51.759345]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> [   51.759976] RIP: 0033:0x7ff331577232
> [   51.760419] Code: c0 e9 c2 fe ff ff 50 48 8d 3d 0a 16 0a 00 e8 05 f1 01 00 0f 1f 44 00 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 0f 05 <48> 3d 00 f0 ff ff 77 56 c3 0f 1f 44 00 00 48 83 ec 28 48 89 54 24
> [   51.763124] RSP: 002b:00007ffdaae3e8b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
> [   51.764430] RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007ff331577232
> [   51.765690] RDX: 0000000000020000 RSI: 00007ff32447e000 RDI: 0000000000000003
> [   51.766937] RBP: 00007ff32447e000 R08: 00007ff32447d010 R09: 0000000000000000
> [   51.769215] R10: 0000000000000022 R11: 0000000000000246 R12: 00005632bd03d1f0
> [   51.770531] R13: 0000000000000003 R14: 0000000000020000 R15: 0000000000020000
> [   51.771816] Modules linked in:
> [   51.772637] CR2: 000000007cfa9028
> [   51.773462] ---[ end trace 0eb61054f7dfd62d ]---

BTW, just tried revert below patch
x86-efi-Add-efi_fake_mem-support-for-EFI_MEMORY_SP.patch

Then the first issue did not happen any more, but the second one (cat
/proc/iomem issue) still happened.

Thanks
Dave