[PATCH 0/3] block/nvme: Fix NVMeRegs alignment/packing and use atomic operations

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

Fix a compiler optimization problem introduced in commit
e5ff22ba9fc ("block/nvme: Pair doorbell registers"),
use atomic operations.

For some not understood yet reason using atomic_and triggers
a NMI on x86 arch. Using the following snippet on top of this
series:

-- >8 --
-    atomic_set(&s->regs->ctrl.cc,
-               cpu_to_le32(atomic_read(&s->regs->ctrl.cc) & const_le32(0xFE)=
));
+    atomic_and(&s->regs->ctrl.cc, const_le32(0xFE));
---

triggers:

 {1}[Hardware Error]: Hardware error from APEI Generic Hardware Error Source:=
 3
 {1}[Hardware Error]: event severity: fatal
 {1}[Hardware Error]:  Error 0, type: fatal
 {1}[Hardware Error]:   section_type: PCIe error
 {1}[Hardware Error]:   port_type: 0, PCIe end point
 {1}[Hardware Error]:   version: 1.16
 {1}[Hardware Error]:   command: 0x0006, status: 0x0010
 {1}[Hardware Error]:   device_id: 0000:04:00.0
 {1}[Hardware Error]:   slot: 0
 {1}[Hardware Error]:   secondary_bus: 0x00
 {1}[Hardware Error]:   vendor_id: 0x8086, device_id: 0x2701
 {1}[Hardware Error]:   class_code: 010802
 {1}[Hardware Error]:   aer_uncor_status: 0x00100000, aer_uncor_mask: 0x00018=
000
 {1}[Hardware Error]:   aer_uncor_severity: 0x000e7030
 {1}[Hardware Error]:   TLP Header: 33000000 00000000 00000000 00000000
 Kernel panic - not syncing: Fatal hardware error!
 CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.6.8-100.fc30.x86_64 #1
 Hardware name: Dell Inc. PowerEdge R430/03XKDV, BIOS 1.2.6 06/08/2015
 Call Trace:
  <NMI>
  dump_stack+0x66/0x90
  panic+0xf1/0x2d3
  __ghes_panic.part.0+0x26/0x26
  ghes_notify_nmi.cold+0x5/0x5
  nmi_handle+0x66/0x120
  default_do_nmi+0x45/0x100
  do_nmi+0x165/0x1d0
  end_repeat_nmi+0x16/0x50
 RIP: 0010:intel_idle+0x82/0x130
 Code: 65 48 8b 04 25 c0 8b 01 00 0f 01 c8 48 8b 00 a8 08 75 17 e9 07 00 00 0=
0 0f 00 2d f5 cd 6d 00 b9 01 00 00 00 48 89 d8 0f 01 c9 <65> 48 8b 04 25 c0 8=
b 01 00 f0 80 60 02 df f0 83 44 24 fc 00 b
 RSP: 0018:ffffffffa8603e30 EFLAGS: 00000046
 RAX: 0000000000000001 RBX: 0000000000000001 RCX: 0000000000000001
 RDX: 0000000000000000 RSI: ffffffffa875edc0 RDI: 0000000000000000
 RBP: ffffffffa875edc0 R08: 00000013ef2b797f R09: 000000000000ba42
 R10: 00000000000993b3 R11: ffffa070afc29ca4 R12: 0000000000000002
 R13: ffffffffa875edc0 R14: 0000000000000002 R15: ffffffffa8614840
  ? intel_idle+0x82/0x130
  ? intel_idle+0x82/0x130
  </NMI>
  cpuidle_enter_state+0x81/0x3e0
  cpuidle_enter+0x29/0x40
  do_idle+0x1c0/0x260
  cpu_startup_entry+0x19/0x20
  start_kernel+0x7ad/0x7ba
  secondary_startup_64+0xb6/0xc0
 Kernel Offset: 0x26000000 from 0xffffffff81000000 (relocation range: 0xfffff=
fff80000000-0xffffffffbfffffff)

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>

Philippe Mathieu-Daud=C3=A9 (3):
  block/nvme: Initialize constant values with const_le32()
  block/nvme: Use atomic operations instead of 'volatile' keyword
  block/nvme: Align NVMeRegs structure to 4KiB and mark it packed

 block/nvme.c | 55 ++++++++++++++++++++++++++++------------------------
 1 file changed, 30 insertions(+), 25 deletions(-)

--=20
2.26.2