fix(virtio-fs): de-assert interrupts

[mkroening]

Running httpd via virtio-net with virtio-fs also enabled, we run into #1680.

The symptoms are as follows:

1. We set up the virtio-net device.
2. We get an IP via DHCP and get two interrupts during configuration.
3. We set up the virtio-fs device.
4. We mount the virtio-fs directory and get one interrupt during configuration.
5. We never get an virtio interrupt again.
   • Non-interrupt-based networking (with feature = "idle-poll") is not affected.
   • Sending other interrupts such as the serial device interrupt via the keyboard let's us make progress, since we currently always poll the network stack in all interrupts (until fix: Proper network wakers #2086).
   • Virtio-fs does not care, since we block on every operation.

The reason for this issue is related to virtio's ISR status capability:

To avoid an extra access, simply reading this register resets it to 0 and causes the device to de-assert the interrupt.

In this way, driver read of ISR status causes the device to de-assert an interrupt.

The problem is that for some reason, we never read the ISR status register for virtio-fs interrupts. This causes virtio-fs interrupts to never be de-asserted, preventing other virtio interrupt to be triggered.

The fix is straight forward: read the ISR status registers to deassert the virtio-fs interrupt as we already do for the other virtio devices. This PR just duplicates virtio-net's logic. In a follow up PR I will refactor the method name from is_queue_interrupt to something that signals that this is an active operation, not just a getter. In the future, I will merge the logic, deduplicating and unifying the methods.

Closes #1680.

[github-actions]

Benchmark Results

Details

Benchmark	Current: 29a8ad2	Previous: af77eb8	Performance Ratio
startup_benchmark Build Time	99.41 s	96.76 s	1.03 ❗
startup_benchmark File Size	0.82 MB	0.82 MB	1.00 ❗
Startup Time - 1 core	0.94 s (±0.04 s)	0.93 s (±0.03 s)	1.01
Startup Time - 2 cores	0.97 s (±0.03 s)	0.93 s (±0.03 s)	1.04
Startup Time - 4 cores	0.97 s (±0.03 s)	0.95 s (±0.04 s)	1.02
multithreaded_benchmark Build Time	101.75 s	94.96 s	1.07 ❗
multithreaded_benchmark File Size	0.96 MB	0.96 MB	1.00 ❗
Multithreaded Pi Efficiency - 2 Threads	89.38 % (±7.03 %)	88.34 % (±8.83 %)	1.01
Multithreaded Pi Efficiency - 4 Threads	44.32 % (±2.96 %)	43.96 % (±2.87 %)	1.01
Multithreaded Pi Efficiency - 8 Threads	25.56 % (±1.80 %)	25.67 % (±1.88 %)	1.00
micro_benchmarks Build Time	114.06 s	107.03 s	1.07 ❗
micro_benchmarks File Size	0.97 MB	0.97 MB	1.00 ❗
Scheduling time - 1 thread	72.32 ticks (±4.96 ticks)	68.40 ticks (±2.80 ticks)	1.06
Scheduling time - 2 threads	39.98 ticks (±5.22 ticks)	36.75 ticks (±3.77 ticks)	1.09
Micro - Time for syscall (getpid)	3.66 ticks (±0.35 ticks)	3.72 ticks (±0.30 ticks)	0.98
Memcpy speed - (built_in) block size 4096	64939.19 MByte/s (±46463.88 MByte/s)	65936.06 MByte/s (±46962.77 MByte/s)	0.98
Memcpy speed - (built_in) block size 1048576	30122.60 MByte/s (±25106.05 MByte/s)	29711.39 MByte/s (±24468.80 MByte/s)	1.01
Memcpy speed - (built_in) block size 16777216	24314.25 MByte/s (±20484.53 MByte/s)	28572.31 MByte/s (±23801.85 MByte/s)	0.85
Memset speed - (built_in) block size 4096	65802.64 MByte/s (±47068.47 MByte/s)	66224.66 MByte/s (±47148.82 MByte/s)	0.99
Memset speed - (built_in) block size 1048576	30856.18 MByte/s (±25516.97 MByte/s)	30455.87 MByte/s (±24906.53 MByte/s)	1.01
Memset speed - (built_in) block size 16777216	25077.73 MByte/s (±20978.65 MByte/s)	29305.64 MByte/s (±24204.32 MByte/s)	0.86
Memcpy speed - (rust) block size 4096	56583.86 MByte/s (±41497.16 MByte/s)	59811.41 MByte/s (±43763.94 MByte/s)	0.95
Memcpy speed - (rust) block size 1048576	30093.61 MByte/s (±25060.67 MByte/s)	29629.02 MByte/s (±24504.10 MByte/s)	1.02
Memcpy speed - (rust) block size 16777216	25339.32 MByte/s (±21380.44 MByte/s)	28401.51 MByte/s (±23669.15 MByte/s)	0.89
Memset speed - (rust) block size 4096	57708.86 MByte/s (±42316.65 MByte/s)	60851.37 MByte/s (±44540.62 MByte/s)	0.95
Memset speed - (rust) block size 1048576	30861.29 MByte/s (±25475.71 MByte/s)	30426.48 MByte/s (±24959.19 MByte/s)	1.01
Memset speed - (rust) block size 16777216	26085.84 MByte/s (±21836.24 MByte/s)	29175.93 MByte/s (±24111.52 MByte/s)	0.89
alloc_benchmarks Build Time	103.50 s	102.72 s	1.01 ❗
alloc_benchmarks File Size	0.89 MB	0.89 MB	1.00 ❗
Allocations - Allocation success	100.00 %	100.00 %	1
Allocations - Deallocation success	100.00 %	100.00 %	1
Allocations - Pre-fail Allocations	100.00 %	100.00 %	1
Allocations - Average Allocation time	10867.18 Ticks (±160.69 Ticks)	8547.70 Ticks (±113.80 Ticks)	1.27 ❗
Allocations - Average Allocation time (no fail)	10867.18 Ticks (±160.69 Ticks)	8547.70 Ticks (±113.80 Ticks)	1.27 ❗
Allocations - Average Deallocation time	963.68 Ticks (±307.52 Ticks)	1117.79 Ticks (±513.75 Ticks)	0.86
mutex_benchmark Build Time	105.38 s	111.82 s	0.94 ❗
mutex_benchmark File Size	0.97 MB	0.97 MB	1.00 ❗
Mutex Stress Test Average Time per Iteration - 1 Threads	12.98 ns (±0.68 ns)	13.38 ns (±0.85 ns)	0.97
Mutex Stress Test Average Time per Iteration - 2 Threads	15.34 ns (±0.65 ns)	15.68 ns (±0.79 ns)	0.98

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