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Alexey Kardashevskiy 345077c8e1 KVM: PPC: Book3S: Protect memslots while validating user address 
Guest physical to user address translation uses KVM memslots and reading
these requires holding the kvm->srcu lock. However recently introduced
kvmppc_tce_validate() broke the rule (see the lockdep warning below).

This moves srcu_read_lock(&vcpu->kvm->srcu) earlier to protect
kvmppc_tce_validate() as well.

=============================
WARNING: suspicious RCU usage
5.1.0-rc2-le_nv2_aikATfstn1-p1 #380 Not tainted
-----------------------------
include/linux/kvm_host.h:605 suspicious rcu_dereference_check() usage!

other info that might help us debug this:

rcu_scheduler_active = 2, debug_locks = 1
1 lock held by qemu-system-ppc/8020:
 #0: 0000000094972fe9 (&vcpu->mutex){+.+.}, at: kvm_vcpu_ioctl+0xdc/0x850 [kvm]

stack backtrace:
CPU: 44 PID: 8020 Comm: qemu-system-ppc Not tainted 5.1.0-rc2-le_nv2_aikATfstn1-p1 #380
Call Trace:
[c000003fece8f740] [c000000000bcc134] dump_stack+0xe8/0x164 (unreliable)
[c000003fece8f790] [c000000000181be0] lockdep_rcu_suspicious+0x130/0x170
[c000003fece8f810] [c0000000000d5f50] kvmppc_tce_to_ua+0x280/0x290
[c000003fece8f870] [c00800001a7e2c78] kvmppc_tce_validate+0x80/0x1b0 [kvm]
[c000003fece8f8e0] [c00800001a7e3fac] kvmppc_h_put_tce+0x94/0x3e4 [kvm]
[c000003fece8f9a0] [c00800001a8baac4] kvmppc_pseries_do_hcall+0x30c/0xce0 [kvm_hv]
[c000003fece8fa10] [c00800001a8bd89c] kvmppc_vcpu_run_hv+0x694/0xec0 [kvm_hv]
[c000003fece8fae0] [c00800001a7d95dc] kvmppc_vcpu_run+0x34/0x48 [kvm]
[c000003fece8fb00] [c00800001a7d56bc] kvm_arch_vcpu_ioctl_run+0x2f4/0x400 [kvm]
[c000003fece8fb90] [c00800001a7c3618] kvm_vcpu_ioctl+0x460/0x850 [kvm]
[c000003fece8fd00] [c00000000041c4f4] do_vfs_ioctl+0xe4/0x930
[c000003fece8fdb0] [c00000000041ce04] ksys_ioctl+0xc4/0x110
[c000003fece8fe00] [c00000000041ce78] sys_ioctl+0x28/0x80
[c000003fece8fe20] [c00000000000b5a4] system_call+0x5c/0x70

Fixes: 42de7b9e21 ("KVM: PPC: Validate TCEs against preregistered memory page sizes", 2018-09-10)
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
2019-04-05 14:37:24 +11:00
arch KVM: PPC: Book3S: Protect memslots while validating user address 2019-04-05 14:37:24 +11:00
block io_uring-20190323 2019-03-23 10:25:12 -07:00
certs kexec, KEYS: Make use of platform keyring for signature verify 2019-02-04 17:34:07 -05:00
crypto lib/lzo: separate lzo-rle from lzo 2019-03-07 18:32:03 -08:00
Documentation Documentation: kvm: clarify KVM_SET_USER_MEMORY_REGION 2019-03-28 17:30:11 +01:00
drivers Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-03-24 11:09:47 -07:00
fs Miscellaneous ext4 bug fixes for 5.1. 2019-03-24 13:41:37 -07:00
include KVM: export <linux/kvm_para.h> and <asm/kvm_para.h> iif KVM is supported 2019-03-28 17:27:42 +01:00
init init/main: add checks for the return value of memblock_alloc*() 2019-03-12 10:04:02 -07:00
ipc Merge branch 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-03-12 14:08:19 -07:00
kernel Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-03-24 11:42:10 -07:00
lib Kbuild updates for v5.1 (2nd) 2019-03-17 13:25:26 -07:00
LICENSES LICENSES: Add GCC runtime library exception text 2019-01-16 14:54:15 -07:00
mm device-dax for 5.1 2019-03-16 13:05:32 -07:00
net libceph: wait for latest osdmap in ceph_monc_blacklist_add() 2019-03-20 16:27:40 +01:00
samples Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-03-11 08:54:01 -07:00
scripts kconfig: remove stale lxdialog/.gitignore 2019-03-17 15:47:02 +09:00
security selinux: fix NULL dereference in policydb_destroy() 2019-03-18 12:19:48 -04:00
sound sound fixes for 5.1-rc2 2019-03-22 14:04:38 -07:00
tools KVM: selftests: complete IO before migrating guest state 2019-03-28 17:29:09 +01:00
usr user/Makefile: Fix typo and capitalization in comment section 2018-12-11 00:18:03 +09:00
virt KVM/ARM fixes for 5.1 2019-03-28 19:07:30 +01:00
.clang-format Merge branch 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-03-12 13:43:42 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: Add support for DT binding schema checks 2018-12-13 09:41:32 -06:00
.mailmap .mailmap: Add Mathieu Othacehe 2019-02-21 11:41:19 +00:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS Char/Misc driver patches for 5.1-rc1 2019-03-06 14:18:59 -08:00
Kbuild Kbuild updates for v5.1 2019-03-10 17:48:21 -07:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS io_uring-20190323 2019-03-23 10:25:12 -07:00
Makefile Linux 5.1-rc2 2019-03-24 14:02:26 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

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.