Uhyve mounts in arbitrary paths

[jounathaen]

This allows Uhyve to announce multiple "mounts" via FDT.

Uhyve places the folders to be mounted in the FDT as follows

    uhyve,mounts {
        mounts ="/dir1\0/dir2\0/dir3\0"
    };

This does not yet allow single file mounts, but should already help in a lot of scenarios.

Fixes #1572

[github-actions]

Benchmark Results

Benchmark	Current: 6d214f0	Previous: c6484a7	Performance Ratio
startup_benchmark Build Time	117.82 s	109.12 s	1.08
startup_benchmark File Size	0.91 MB	0.90 MB	1.01
Startup Time - 1 core	0.91 s (±0.03 s)	0.88 s (±0.02 s)	1.03
Startup Time - 2 cores	0.92 s (±0.03 s)	0.87 s (±0.02 s)	1.05
Startup Time - 4 cores	0.96 s (±0.03 s)	0.87 s (±0.03 s)	1.10
multithreaded_benchmark Build Time	116.64 s	104.93 s	1.11
multithreaded_benchmark File Size	1.01 MB	1.01 MB	1.01
Multithreaded Pi Efficiency - 2 Threads	87.48 % (±9.20 %)	3.66 % (±17.59 %)	23.87
Multithreaded Pi Efficiency - 4 Threads	43.88 % (±3.46 %)	1.91 % (±9.18 %)	22.95
Multithreaded Pi Efficiency - 8 Threads	25.25 % (±1.82 %)	1.02 % (±4.90 %)	24.73
micro_benchmarks Build Time	118.49 s	102.53 s	1.16
micro_benchmarks File Size	1.02 MB	1.01 MB	1.01
Scheduling time - 1 thread	70.10 ticks (±4.09 ticks)	2.54 ticks (±12.22 ticks)	27.55
Scheduling time - 2 threads	40.46 ticks (±4.82 ticks)	1.29 ticks (±6.17 ticks)	31.46
Micro - Time for syscall (getpid)	3.23 ticks (±0.55 ticks)	0.11 ticks (±0.53 ticks)	29.30
Memcpy speed - (built_in) block size 4096	76001.34 MByte/s (±52716.65 MByte/s)	1662.23 MByte/s (±7978.72 MByte/s)	45.72
Memcpy speed - (built_in) block size 1048576	42160.40 MByte/s (±29216.45 MByte/s)	802.31 MByte/s (±3851.09 MByte/s)	52.55
Memcpy speed - (built_in) block size 16777216	27813.77 MByte/s (±22809.42 MByte/s)	231.25 MByte/s (±1110.01 MByte/s)	120.27
Memset speed - (built_in) block size 4096	76197.54 MByte/s (±52842.95 MByte/s)	1875.00 MByte/s (±9000.00 MByte/s)	40.64
Memset speed - (built_in) block size 1048576	42414.33 MByte/s (±29385.86 MByte/s)	1009.80 MByte/s (±4847.02 MByte/s)	42.00
Memset speed - (built_in) block size 16777216	28548.82 MByte/s (±23235.29 MByte/s)	995.24 MByte/s (±4777.13 MByte/s)	28.69
Memcpy speed - (rust) block size 4096	68306.50 MByte/s (±47835.20 MByte/s)	1463.41 MByte/s (±7024.39 MByte/s)	46.68
Memcpy speed - (rust) block size 1048576	42155.88 MByte/s (±29204.14 MByte/s)	795.04 MByte/s (±3816.19 MByte/s)	53.02
Memcpy speed - (rust) block size 16777216	27658.49 MByte/s (±22660.70 MByte/s)	236.47 MByte/s (±1135.06 MByte/s)	116.96
Memset speed - (rust) block size 4096	68786.15 MByte/s (±48216.10 MByte/s)	1846.15 MByte/s (±8861.54 MByte/s)	37.26
Memset speed - (rust) block size 1048576	42379.12 MByte/s (±29356.73 MByte/s)	1016.88 MByte/s (±4881.03 MByte/s)	41.68
Memset speed - (rust) block size 16777216	28373.17 MByte/s (±23073.87 MByte/s)	993.35 MByte/s (±4768.08 MByte/s)	28.56
alloc_benchmarks Build Time	108.99 s	100.75 s	1.08
alloc_benchmarks File Size	0.98 MB	0.97 MB	1.01
Allocations - Allocation success	100.00 %	2.00 % (±13.86 %)	50
Allocations - Deallocation success	69.99 % (±0.32 %)	1.40 % (±9.73 %)	49.83
Allocations - Pre-fail Allocations	100.00 %	2.00 % (±13.86 %)	50
Allocations - Average Allocation time	12153.29 Ticks (±236.69 Ticks)	229.53 Ticks (±1590.58 Ticks)	52.95
Allocations - Average Allocation time (no fail)	12153.29 Ticks (±236.69 Ticks)	229.53 Ticks (±1590.58 Ticks)	52.95
Allocations - Average Deallocation time	728.27 Ticks (±73.24 Ticks)	13.15 Ticks (±91.10 Ticks)	55.39
mutex_benchmark Build Time	110.10 s	101.46 s	1.09
mutex_benchmark File Size	1.02 MB	1.01 MB	1.01
Mutex Stress Test Average Time per Iteration - 1 Threads	13.36 ns (±0.66 ns)	0.24 ns (±1.66 ns)	55.67
Mutex Stress Test Average Time per Iteration - 2 Threads	15.88 ns (±1.27 ns)	0.26 ns (±1.80 ns)	61.08

This comment was automatically generated by workflow using github-action-benchmark.

[mkroening]

A few ideas :)

[mkroening]

Suggested change

	fdt.find_node("/uhyve,mounts").and_then(|node| {
	node.property("mounts")
	.and_then(|property| str::from_utf8(property.value).ok())
	})
	fdt.find_node("/uhyve,mounts")
	.and_then(|node| node.property("mounts"))
	.and_then(|property| property.as_str())

[mkroening]

This is already done in as_str in my previous suggestion.

Suggested change

	for mount_point in mount_str.trim_end_matches('\0').split('\0') {
	for mount_point in mount_str.split('\0') {

[jounathaen]

This doesn't work, as the last element in mount_str also ends on \0, thus creating an empy string for mount_point.

[mkroening]

That's why I mentioned the previous suggestion. as_str removes the trailing null.

[mkroening]

Should we check the error and only attempt recovery on EBADF similar to create_dir_recursive?