Marc Zyngier a6ecfb11bf KVM: arm/arm64: vgic-its: Take the srcu lock when writing to guest memory ... When halting a guest, QEMU flushes the virtual ITS caches, which amounts to writing to the various tables that the guest has allocated. When doing this, we fail to take the srcu lock, and the kernel shouts loudly if running a lockdep kernel: [ 69.680416] ============================= [ 69.680819] WARNING: suspicious RCU usage [ 69.681526] 5.1.0-rc1-00008-g600025238f51-dirty #18 Not tainted [ 69.682096] ----------------------------- [ 69.682501] ./include/linux/kvm_host.h:605 suspicious rcu_dereference_check() usage! [ 69.683225] [ 69.683225] other info that might help us debug this: [ 69.683225] [ 69.683975] [ 69.683975] rcu_scheduler_active = 2, debug_locks = 1 [ 69.684598] 6 locks held by qemu-system-aar/4097: [ 69.685059] #0: 0000000034196013 (&kvm->lock){+.+.}, at: vgic_its_set_attr+0x244/0x3a0 [ 69.686087] #1: 00000000f2ed935e (&its->its_lock){+.+.}, at: vgic_its_set_attr+0x250/0x3a0 [ 69.686919] #2: 000000005e71ea54 (&vcpu->mutex){+.+.}, at: lock_all_vcpus+0x64/0xd0 [ 69.687698] #3: 00000000c17e548d (&vcpu->mutex){+.+.}, at: lock_all_vcpus+0x64/0xd0 [ 69.688475] #4: 00000000ba386017 (&vcpu->mutex){+.+.}, at: lock_all_vcpus+0x64/0xd0 [ 69.689978] #5: 00000000c2c3c335 (&vcpu->mutex){+.+.}, at: lock_all_vcpus+0x64/0xd0 [ 69.690729] [ 69.690729] stack backtrace: [ 69.691151] CPU: 2 PID: 4097 Comm: qemu-system-aar Not tainted 5.1.0-rc1-00008-g600025238f51-dirty #18 [ 69.691984] Hardware name: rockchip evb_rk3399/evb_rk3399, BIOS 2019.04-rc3-00124-g2feec69fb1 03/15/2019 [ 69.692831] Call trace: [ 69.694072] lockdep_rcu_suspicious+0xcc/0x110 [ 69.694490] gfn_to_memslot+0x174/0x190 [ 69.694853] kvm_write_guest+0x50/0xb0 [ 69.695209] vgic_its_save_tables_v0+0x248/0x330 [ 69.695639] vgic_its_set_attr+0x298/0x3a0 [ 69.696024] kvm_device_ioctl_attr+0x9c/0xd8 [ 69.696424] kvm_device_ioctl+0x8c/0xf8 [ 69.696788] do_vfs_ioctl+0xc8/0x960 [ 69.697128] ksys_ioctl+0x8c/0xa0 [ 69.697445] __arm64_sys_ioctl+0x28/0x38 [ 69.697817] el0_svc_common+0xd8/0x138 [ 69.698173] el0_svc_handler+0x38/0x78 [ 69.698528] el0_svc+0x8/0xc The fix is to obviously take the srcu lock, just like we do on the read side of things since bf308242ab. One wonders why this wasn't fixed at the same time, but hey... Fixes: bf308242ab ("KVM: arm/arm64: VGIC/ITS: protect kvm_read_guest() calls with SRCU lock") Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>		2019-03-19 17:56:56 +00:00
..
hyp	arm64: KVM: Always set ICH_HCR_EL2.EN if GICv4 is enabled	2019-03-19 17:56:34 +00:00
vgic	KVM: arm/arm64: vgic-its: Take the srcu lock when writing to guest memory	2019-03-19 17:56:56 +00:00
aarch32.c	kvm/arm: use PSR_AA32 definitions	2018-07-05 17:24:15 +01:00
arch_timer.c	KVM: arm/arm64: Remove unused timer variable	2019-02-22 09:41:52 +00:00
arm.c	ARM: some cleanups, direct physical timer assignment, cache sanitization	2019-03-15 15:00:28 -07:00
mmio.c	arm64: KVM: Skip MMIO insn after emulation	2018-12-18 14:10:36 +00:00
mmu.c	ARM: some cleanups, direct physical timer assignment, cache sanitization	2019-03-15 15:00:28 -07:00
perf.c	KVM: arm/arm64: Move shared files to virt/kvm/arm	2017-05-04 13:57:26 +02:00
pmu.c	KVM: arm64: Rewrite system register accessors to read/write functions	2018-03-19 10:53:16 +00:00
psci.c	arm/arm64: KVM: Allow a VCPU to fully reset itself	2019-02-07 11:44:13 +00:00
trace.h	KVM: arm/arm64: Fix TRACE_INCLUDE_PATH	2019-02-19 21:05:51 +00:00