#!/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.
shopt -s nullglob

[[ $(uname -s) == Linux ]] || exit 0
# Use MSR instead?
[[ $(< /sys/class/dmi/id/chassis_vendor) == QEMU ]] || exit 0

get_bar() {
	echo "0x$(setpci -s "$1" "$2.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/unassigned"
}

info() {
	local dev=$1

	local pref loc

	local base_addr2
	local base_addr4

	local bar local bar2 bar3 bar4 bar5
	local bar_type2

	pref[0]=non-prefetchable
	pref[1]=prefetchable

	print_info() {
		local bar=$1 base_addr=$2 bar_type=$3

		printf '%s:%s:%s:%s:%s:%s\n' \
			"${nvme##*/}" \
			"$dev" \
			"64-bit" \
			"${pref[bar & 1 << 3 ? 1 : 0]}" \
			"$(get_size "$base_addr")" \
			"$bar_type"
	}

	bar2=$(get_bar "$dev" 0x18)
	bar3=$(get_bar "$dev" 0x1c)
	bar4=$(get_bar "$dev" 0x20)
	bar5=$(get_bar "$dev" 0x24)

	# QEMU uses 64-bit BARs
	if ((bar2 & 1 << 2)); then
		bar_type2=pmr
		if [[ -e $nvme/cmb ]]; then
			bar_type2=cmb
		fi
		base_addr2=$(((bar2 & ~0xf) + (bar3 << 32)))
		print_info "$bar2" "$base_addr2" "$bar_type2"
	fi
	# QEMU uses 64-bit BARs
	if ((bar4 & 1 << 2)); then
		base_addr4=$(((bar4 & ~0xf) + (bar5 << 32)))
		print_info "$bar4" "$base_addr4" pmr
	fi
}

for nvme in /sys/class/nvme/nvme*; do
	pci=$(readlink -f "$nvme/device") pci=${pci##*/}
	info "$pci"
done