From 119e9db233ad0f4cbd4cfb9f9385a7bca378b37d Mon Sep 17 00:00:00 2001 From: Zeng Chi Date: Mon, 21 Sep 2026 18:24:42 +0800 Subject: KVM: Don't pre-reserve xarray entries when storing empty/NULL attributes Skip the xarray reservation loop when clearing all memory attributes, as storing NULL only erases the entry and never needs to allocate, so no reservation (and no cleanup of a failed one) is required in that case. Suggested-by: Sean Christopherson Cc: David Ballesteros Signed-off-by: Zeng Chi Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com [sean: split to separate patch] Signed-off-by: Sean Christopherson --- Documentation/ABI/testing/sysfs-devices-mapping | 62 +++++++++++++++++++++++++ 1 file changed, 62 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-devices-mapping (limited to 'Documentation/ABI/testing/sysfs-devices-mapping') diff --git a/Documentation/ABI/testing/sysfs-devices-mapping b/Documentation/ABI/testing/sysfs-devices-mapping new file mode 100644 index 000000000..2eee1446a --- /dev/null +++ b/Documentation/ABI/testing/sysfs-devices-mapping @@ -0,0 +1,62 @@ +What: /sys/devices/uncore_iio_x/dieX +Date: February 2020 +Contact: Alexander Antonov +Description: + Each IIO stack (PCIe root port) has its own IIO PMON block, so + each dieX file (where X is die number) holds "Segment:Root Bus" + for PCIe root port, which can be monitored by that IIO PMON + block. + For example, on 4-die Xeon platform with up to 6 IIO stacks per + die and, therefore, 6 IIO PMON blocks per die, the mapping of + IIO PMON block 0 exposes as the following:: + + $ ls /sys/devices/uncore_iio_0/die* + -r--r--r-- /sys/devices/uncore_iio_0/die0 + -r--r--r-- /sys/devices/uncore_iio_0/die1 + -r--r--r-- /sys/devices/uncore_iio_0/die2 + -r--r--r-- /sys/devices/uncore_iio_0/die3 + + $ tail /sys/devices/uncore_iio_0/die* + ==> /sys/devices/uncore_iio_0/die0 <== + 0000:00 + ==> /sys/devices/uncore_iio_0/die1 <== + 0000:40 + ==> /sys/devices/uncore_iio_0/die2 <== + 0000:80 + ==> /sys/devices/uncore_iio_0/die3 <== + 0000:c0 + + Which means:: + + IIO PMU 0 on die 0 belongs to PCI RP on bus 0x00, domain 0x0000 + IIO PMU 0 on die 1 belongs to PCI RP on bus 0x40, domain 0x0000 + IIO PMU 0 on die 2 belongs to PCI RP on bus 0x80, domain 0x0000 + IIO PMU 0 on die 3 belongs to PCI RP on bus 0xc0, domain 0x0000 + +What: /sys/devices/uncore_upi_x/dieX +Date: March 2022 +Contact: Alexander Antonov +Description: + Each /sys/devices/uncore_upi_X/dieY file holds "upi_Z,die_W" + value that means UPI link number X on die Y is connected to UPI + link Z on die W and this link between sockets can be monitored + by UPI PMON block. + For example, 4-die Sapphire Rapids platform has the following + UPI 0 topology:: + + # tail /sys/devices/uncore_upi_0/die* + ==> /sys/devices/uncore_upi_0/die0 <== + upi_1,die_1 + ==> /sys/devices/uncore_upi_0/die1 <== + upi_0,die_3 + ==> /sys/devices/uncore_upi_0/die2 <== + upi_1,die_3 + ==> /sys/devices/uncore_upi_0/die3 <== + upi_0,die_1 + + Which means:: + + UPI link 0 on die 0 is connected to UPI link 1 on die 1 + UPI link 0 on die 1 is connected to UPI link 0 on die 3 + UPI link 0 on die 2 is connected to UPI link 1 on die 3 + UPI link 0 on die 3 is connected to UPI link 0 on die 1 \ No newline at end of file -- cgit v1.3.1