scripts: Add helper script for looking up PMR info under qemu

#!/usr/bin/env bash

# We simply check if BAR2 is present as that's where PMR or CMB is

# meant to be located under qemu. If found, print some stats then exit.

[[ $(uname -s) == Linux ]] || exit 0

# Use MSR instead?

[[ $(< /sys/class/dmi/id/chassis_vendor) == QEMU ]] || exit 0

get_bar2() {

	echo "0x$(setpci -s "$1" 0x18.L)"

}

get_size() {

	local addr=$1

	local start end type

	while IFS="- " read -r start end type; do

		start=0x$start end=0x$end

		if ((start == addr)) && [[ $type == *"$pci"* ]]; then

			printf '0x%08x:0x%08x:0x%08x\n' \

				"$start" "$end" $((end - start + 1))

			return 0

		fi

	done < /proc/iomem

	echo "unknown"

}

info() {

	local bar=$1

	local pref loc

	pref[0]=non-prefetchable

	pref[1]=prefetchable

	loc[0]=32-bit

	loc[1]="<1MiB"

	loc[2]=64-bit

	echo "${loc[(bar >> 1) & 0x3]}:${pref[bar & 1 << 3 ? 1 : 0]}:$(get_size $((bar & ~0xf)))"

}

for nvme in /sys/class/nvme/nvme*; do

	pci=$(readlink -f "$nvme/device") pci=${pci##*/}

	bar2=$(get_bar2 "$pci") || continue

	((bar2 != 0x0)) || continue

	bar=pmr

	[[ -e $nvme/cmb ]] && bar=cmb

	echo "${nvme##*/}:$pci:$(info "$bar2"):$bar"

done