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nvme: add opcode filtering for fault injection

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Currently NVMe fault injection applies to every command routed through
nvme_should_fail(), which makes it hard to target a specific command
type when reproducing an issue in error-handling paths.

Add an "opcode" debugfs attribute alongside the existing "status" and
"dont_retry" knobs. It defaults to 0xffff, meaning "match any opcode"
and preserving the previous behavior. When set to a valid opcode
(<= 0xff), fault injection is only considered for commands whose opcode
matches.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Mohamed Khalfella <mkhalfella@purestorage.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
This commit is contained in:
Mohamed Khalfella 2026-08-11 16:11:52 -07:00 committed by Keith Busch
parent 56e1c6bbe4
commit 58e7c13c8f
3 changed files with 78 additions and 2 deletions
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65
Documentation/fault-injection/nvme-fault-injection.rst
View File

@ -176,3 +176,68 @@ Message from dmesg::
secondary_startup_64+0xa4/0xb0
nvme nvme0: Could not set queue count (16385)
nvme nvme0: IO queues not created
Example 4: Inject an error into the first write command
-------------------------------------------------------
::
echo 0x01 > /sys/kernel/debug/nvme0n1/fault_inject/opcode
echo 1 > /sys/kernel/debug/nvme0n1/fault_inject/times
echo 100 > /sys/kernel/debug/nvme0n1/fault_inject/probability
dd if=/dev/zero of=/dev/nvme0n1 oflag=direct bs=512 count=1
Expected Result::
The first write command sent to nvme0n1 fails
Message from dmesg::
FAULT_INJECTION: forcing a failure.
name fault_inject, interval 1, probability 100, space 0, times 1
CPU: 4 UID: 0 PID: 0 Comm: swapper/4 Not tainted 7.1.0+ #5 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-20240910_120124-localhost 04/01/2014
Call Trace:
<IRQ>
dump_stack_lvl+0x6e/0xa0
dump_stack+0x10/0x16
should_fail_ex+0x461/0x510
should_fail+0xb/0x20
nvme_should_fail+0x11b/0x240 [nvme_core]
nvme_poll_cq+0x6ad/0xb30 [nvme]
nvme_irq+0x84/0xe0 [nvme]
? __pfx_nvme_irq+0x10/0x10 [nvme]
? rcu_core+0xa40/0xa90
? __pfx_sched_balance_softirq+0x10/0x10
? debug_smp_processor_id+0x17/0x20
? rcu_is_watching+0x13/0xa0
__handle_irq_event_percpu+0x396/0x610
handle_irq_event_percpu+0xf/0x90
handle_irq_event+0xab/0x110
handle_edge_irq+0x1a3/0x210
__common_interrupt+0xff/0x170
common_interrupt+0x90/0xc0
</IRQ>
<TASK>
asm_common_interrupt+0x27/0x40
RIP: 0010:pv_native_safe_halt+0x13/0x20
Code: 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 8b 05 0a 2a 58 01 85 c0 7e 07 0f 00 2d ff cc 0d 00 fb f4 <c3> cc 0
RSP: 0018:ffff888100a67e40 EFLAGS: 00000242
RAX: 0000000000000001 RBX: ffff888100a49c40 RCX: ffffed102b6c645b
RDX: ffffed102b6c645b RSI: ffffffff82a0d3c0 RDI: ffffffff81428b9b
RBP: ffff888100a67e48 R08: ffffed102b6c645b R09: 0000000000000004
R10: ffffed102b6c645a R11: 0000000000000001 R12: 0000000000000000
R13: 0000000000000000 R14: ffffed1020149388 R15: dffffc0000000000
? do_idle+0x19b/0x2c0
? default_idle+0x9/0x20
arch_cpu_idle+0x9/0x10
default_idle_call+0x6b/0xa0
do_idle+0x19b/0x2c0
? __pfx_do_idle+0x10/0x10
? complete_with_flags+0x63/0x70
cpu_startup_entry+0x55/0x60
start_secondary+0x1df/0x1e0
common_startup_64+0x13e/0x158
</TASK>
nvme0n1: Write(0x1) @ LBA 0, 1 blocks, Invalid Command Opcode (sct 0x0 / sc 0x1) DNR
operation not supported error, dev nvme0n1, sector 0 op 0x1:(WRITE) flags 0x8800 phys_seg 1 prio class 2

14
drivers/nvme/host/fault_inject.c
View File

@ -42,9 +42,11 @@ void nvme_fault_inject_init(struct nvme_fault_inject *fault_inj,
}
fault_inj->parent = parent;
/* create debugfs for status code and dont_retry */
/* create debugfs for opcode, status code, and dont_retry */
fault_inj->opcode = 0xffff;
fault_inj->status = NVME_SC_INVALID_OPCODE;
fault_inj->dont_retry = true;
debugfs_create_x16("opcode", 0600, dir, &fault_inj->opcode);
debugfs_create_x16("status", 0600, dir, &fault_inj->status);
debugfs_create_bool("dont_retry", 0600, dir, &fault_inj->dont_retry);
}
@ -59,6 +61,7 @@ void nvme_should_fail(struct request *req)
{
struct gendisk *disk = req->q->disk;
struct nvme_fault_inject *fault_inject = NULL;
struct nvme_command *cmd = nvme_req(req)->cmd;
u16 status;
if (disk) {
@ -72,7 +75,14 @@ void nvme_should_fail(struct request *req)
fault_inject = &nvme_req(req)->ctrl->fault_inject;
}
if (fault_inject && should_fail(&fault_inject->attr, 1)) {
if (!fault_inject)
return;
if (fault_inject->opcode <= 0xff &&
fault_inject->opcode != cmd->common.opcode)
return;
if (should_fail(&fault_inject->attr, 1)) {
/* inject status code and DNR bit */
status = fault_inject->status;
if (fault_inject->dont_retry)

1
drivers/nvme/host/nvme.h
View File

@ -323,6 +323,7 @@ struct nvme_fault_inject {
#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
struct fault_attr attr;
struct dentry *parent;
u16 opcode;
bool dont_retry; /* DNR, do not retry */
u16 status; /* status code */
#endif