Hello, This series fixes PM hibernation for hvm guests running on xen hypervisor. The running guest could now be hibernated and resumed successfully at a later time. The fixes for PM hibernation are added to block and network device drivers i.e xen-blkfront and xen-netfront. Any other driver that needs to add S4 support if not already, can follow same method of introducing freeze/thaw/restore callbacks. The patches had been tested against upstream kernel and xen4.11. Large scale testing is also done on Xen based Amazon EC2 instances. All this testing involved running memory exhausting workload in the background. Doing guest hibernation does not involve any support from hypervisor and this way guest has complete control over its state. Infrastructure restrictions for saving up guest state can be overcome by guest initiated hibernation. These patches were send out as RFC before and all the feedback had been incorporated in the patches. The last RFCV3 could be found here: https://lkml.org/lkml/2020/2/14/2789 Known issues: 1.KASLR causes intermittent hibernation failures. VM fails to resumes and has to be restarted. I will investigate this issue separately and shouldn't be a blocker for this patch series. 2. During hibernation, I observed sometimes that freezing of tasks fails due to busy XFS workqueuei[xfs-cil/xfs-sync]. This is also intermittent may be 1 out of 200 runs and hibernation is aborted in this case. Re-trying hibernation may work. Also, this is a known issue with hibernation and some filesystems like XFS has been discussed by the community for years with not an effectve resolution at this point. Testing How to: --------------- 1. Setup xen hypervisor on a physical machine[ I used Ubuntu 16.04 +upstream xen-4.11] 2. Bring up a HVM guest w/t kernel compiled with hibernation patches [I used ubuntu18.04 netboot bionic images and also Amazon Linux on-prem images]. 3. Create a swap file size=RAM size 4. Update grub parameters and reboot 5. Trigger pm-hibernation from within the VM Example: Set up a file-backed swap space. Swap file size>=Total memory on the system sudo dd if=/dev/zero of=/swap bs=$(( 1024 * 1024 )) count=4096 # 4096MiB sudo chmod 600 /swap sudo mkswap /swap sudo swapon /swap Update resume device/resume offset in grub if using swap file: resume=/dev/xvda1 resume_offset=200704 no_console_suspend=1 Execute: -------- sudo pm-hibernate OR echo disk > /sys/power/state && echo reboot > /sys/power/disk Compute resume offset code: " #!/usr/bin/env python import sys import array import fcntl #swap file f = open(sys.argv[1], 'r') buf = array.array('L', [0]) #FIBMAP ret = fcntl.ioctl(f.fileno(), 0x01, buf) print buf[0] " Anchal Agarwal (5): x86/xen: Introduce new function to map HYPERVISOR_shared_info on Resume genirq: Shutdown irq chips in suspend/resume during hibernation xen: Introduce wrapper for save/restore sched clock offset xen: Update sched clock offset to avoid system instability in hibernation PM / hibernate: update the resume offset on SNAPSHOT_SET_SWAP_AREA Munehisa Kamata (7): xen/manage: keep track of the on-going suspend mode xenbus: add freeze/thaw/restore callbacks support x86/xen: add system core suspend and resume callbacks xen-blkfront: add callbacks for PM suspend and hibernation xen-netfront: add callbacks for PM suspend and hibernation xen/time: introduce xen_{save,restore}_steal_clock x86/xen: save and restore steal clock arch/x86/xen/enlighten_hvm.c | 8 ++ arch/x86/xen/suspend.c | 72 ++++++++++++++++++ arch/x86/xen/time.c | 18 ++++- arch/x86/xen/xen-ops.h | 3 + drivers/block/xen-blkfront.c | 122 ++++++++++++++++++++++++++++-- drivers/net/xen-netfront.c | 98 +++++++++++++++++++++++- drivers/xen/events/events_base.c | 1 + drivers/xen/manage.c | 73 ++++++++++++++++++ drivers/xen/time.c | 29 ++++++- drivers/xen/xenbus/xenbus_probe.c | 99 +++++++++++++++++++----- include/linux/irq.h | 2 + include/xen/xen-ops.h | 8 ++ include/xen/xenbus.h | 3 + kernel/irq/chip.c | 2 +- kernel/irq/internals.h | 1 + kernel/irq/pm.c | 31 +++++--- kernel/power/user.c | 6 +- 17 files changed, 536 insertions(+), 40 deletions(-) -- 2.24.1.AMZN
