aedb5b1942
According to Documentation/virtual/kvm/locking.txt, the srcu read lock should be taken when accessing the memslots of the VM. The XIVE KVM device needs to do so when configuring the page of the OS event queue of vCPU for a given priority and when marking the same page dirty before migration. This avoids warnings such as : [ 208.224882] ============================= [ 208.224884] WARNING: suspicious RCU usage [ 208.224889] 5.2.0-rc2-xive+ #47 Not tainted [ 208.224890] ----------------------------- [ 208.224894] ../include/linux/kvm_host.h:633 suspicious rcu_dereference_check() usage! [ 208.224896] other info that might help us debug this: [ 208.224898] rcu_scheduler_active = 2, debug_locks = 1 [ 208.224901] no locks held by qemu-system-ppc/3923. [ 208.224902] stack backtrace: [ 208.224907] CPU: 64 PID: 3923 Comm: qemu-system-ppc Kdump: loaded Not tainted 5.2.0-rc2-xive+ #47 [ 208.224909] Call Trace: [ 208.224918] [c000200cdd98fa30] [c000000000be1934] dump_stack+0xe8/0x164 (unreliable) [ 208.224924] [c000200cdd98fa80] [c0000000001aec80] lockdep_rcu_suspicious+0x110/0x180 [ 208.224935] [c000200cdd98fb00] [c0080000075933a0] gfn_to_memslot+0x1c8/0x200 [kvm] [ 208.224943] [c000200cdd98fb40] [c008000007599600] gfn_to_pfn+0x28/0x60 [kvm] [ 208.224951] [c000200cdd98fb70] [c008000007599658] gfn_to_page+0x20/0x40 [kvm] [ 208.224959] [c000200cdd98fb90] [c0080000075b495c] kvmppc_xive_native_set_attr+0x8b4/0x1480 [kvm] [ 208.224967] [c000200cdd98fca0] [c00800000759261c] kvm_device_ioctl_attr+0x64/0xb0 [kvm] [ 208.224974] [c000200cdd98fcf0] [c008000007592730] kvm_device_ioctl+0xc8/0x110 [kvm] [ 208.224979] [c000200cdd98fd10] [c000000000433a24] do_vfs_ioctl+0xd4/0xcd0 [ 208.224981] [c000200cdd98fdb0] [c000000000434724] ksys_ioctl+0x104/0x120 [ 208.224984] [c000200cdd98fe00] [c000000000434768] sys_ioctl+0x28/0x80 [ 208.224988] [c000200cdd98fe20] [c00000000000b888] system_call+0x5c/0x70 legoater@boss01:~$ Fixes: 13ce3297c576 ("KVM: PPC: Book3S HV: XIVE: Add controls for the EQ configuration") Fixes: e6714bd1671d ("KVM: PPC: Book3S HV: XIVE: Add a control to dirty the XIVE EQ pages") Signed-off-by: Cédric Le Goater <clg@kaod.org> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.