linux/arch/arm64/kvm
James Morse 7d82602909 KVM: arm64: Forbid kprobing of the VHE world-switch code
On systems with VHE the kernel and KVM's world-switch code run at the
same exception level. Code that is only used on a VHE system does not
need to be annotated as __hyp_text as it can reside anywhere in the
kernel text.

__hyp_text was also used to prevent kprobes from patching breakpoint
instructions into this region, as this code runs at a different
exception level. While this is no longer true with VHE, KVM still
switches VBAR_EL1, meaning a kprobe's breakpoint executed in the
world-switch code will cause a hyp-panic.

echo "p:weasel sysreg_save_guest_state_vhe" > /sys/kernel/debug/tracing/kprobe_events
echo 1 > /sys/kernel/debug/tracing/events/kprobes/weasel/enable
lkvm run -k /boot/Image --console serial -p "console=ttyS0 earlycon=uart,mmio,0x3f8"

  # lkvm run -k /boot/Image -m 384 -c 3 --name guest-1474
  Info: Placing fdt at 0x8fe00000 - 0x8fffffff
  Info: virtio-mmio.devices=0x200@0x10000:36

  Info: virtio-mmio.devices=0x200@0x10200:37

  Info: virtio-mmio.devices=0x200@0x10400:38

[  614.178186] Kernel panic - not syncing: HYP panic:
[  614.178186] PS:404003c9 PC:ffff0000100d70e0 ESR:f2000004
[  614.178186] FAR:0000000080080000 HPFAR:0000000000800800 PAR:1d00007edbadc0de
[  614.178186] VCPU:00000000f8de32f1
[  614.178383] CPU: 2 PID: 1482 Comm: kvm-vcpu-0 Not tainted 5.0.0-rc2 #10799
[  614.178446] Call trace:
[  614.178480]  dump_backtrace+0x0/0x148
[  614.178567]  show_stack+0x24/0x30
[  614.178658]  dump_stack+0x90/0xb4
[  614.178710]  panic+0x13c/0x2d8
[  614.178793]  hyp_panic+0xac/0xd8
[  614.178880]  kvm_vcpu_run_vhe+0x9c/0xe0
[  614.178958]  kvm_arch_vcpu_ioctl_run+0x454/0x798
[  614.179038]  kvm_vcpu_ioctl+0x360/0x898
[  614.179087]  do_vfs_ioctl+0xc4/0x858
[  614.179174]  ksys_ioctl+0x84/0xb8
[  614.179261]  __arm64_sys_ioctl+0x28/0x38
[  614.179348]  el0_svc_common+0x94/0x108
[  614.179401]  el0_svc_handler+0x38/0x78
[  614.179487]  el0_svc+0x8/0xc
[  614.179558] SMP: stopping secondary CPUs
[  614.179661] Kernel Offset: disabled
[  614.179695] CPU features: 0x003,2a80aa38
[  614.179758] Memory Limit: none
[  614.179858] ---[ end Kernel panic - not syncing: HYP panic:
[  614.179858] PS:404003c9 PC:ffff0000100d70e0 ESR:f2000004
[  614.179858] FAR:0000000080080000 HPFAR:0000000000800800 PAR:1d00007edbadc0de
[  614.179858] VCPU:00000000f8de32f1 ]---

Annotate the VHE world-switch functions that aren't marked
__hyp_text using NOKPROBE_SYMBOL().

Signed-off-by: James Morse <james.morse@arm.com>
Fixes: 3f5c90b890 ("KVM: arm64: Introduce VHE-specific kvm_vcpu_run")
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2019-02-07 11:44:47 +00:00
..
hyp KVM: arm64: Forbid kprobing of the VHE world-switch code 2019-02-07 11:44:47 +00:00
debug.c arm64: KVM: Consistently advance singlestep when emulating instructions 2018-12-18 14:11:37 +00:00
fpsimd.c KVM: arm64: Avoid mistaken attempts to save SVE state for vcpus 2018-06-21 09:14:44 +01:00
guest.c KVM updates for v4.20 2018-10-25 17:57:35 -07:00
handle_exit.c * ARM: selftests improvements, large PUD support for HugeTLB, 2018-12-26 11:46:28 -08:00
hyp-init.S arm64: KVM: Enable Common Not Private translations 2018-09-18 12:03:34 +01:00
hyp.S arm64: hyp-stub/KVM: Kill __hyp_get_vectors 2017-04-09 07:49:34 -07:00
inject_fault.c arm/arm64: KVM: Add KVM_GET/SET_VCPU_EVENTS 2018-07-21 16:02:30 +01:00
irq.h KVM: arm/arm64: Enable irqchip routing 2016-07-22 18:52:01 +01:00
Kconfig treewide: surround Kconfig file paths with double quotes 2018-12-22 00:25:54 +09:00
Makefile KVM: arm64: Optimise FPSIMD handling to reduce guest/host thrashing 2018-05-25 12:28:28 +01:00
regmap.c kvm/arm: use PSR_AA32 definitions 2018-07-05 17:24:15 +01:00
reset.c arm/arm64: KVM: Allow a VCPU to fully reset itself 2019-02-07 11:44:13 +00:00
sys_regs_generic_v8.c KVM: arm64: Rewrite system register accessors to read/write functions 2018-03-19 10:53:16 +00:00
sys_regs.c arm/arm64: KVM: Don't panic on failure to properly reset system registers 2019-02-07 11:44:46 +00:00
sys_regs.h arm64: KVM: Add trapped system register access tracepoint 2018-12-19 17:47:08 +00:00
trace.h arm64: KVM: Add trapped system register access tracepoint 2018-12-19 17:47:08 +00:00
va_layout.c arm64: KVM: Allow mapping of vectors outside of the RAM region 2018-03-19 13:06:46 +00:00
vgic-sys-reg-v3.c KVM: arm/arm64: Extract GICv3 max APRn index calculation 2017-09-05 17:33:39 +02:00