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* KVM_SET_NESTED_STATE not yet stable
@ 2019-07-08 20:39 Jan Kiszka
  2019-07-10 15:24 ` Raslan, KarimAllah
  0 siblings, 1 reply; 10+ messages in thread
From: Jan Kiszka @ 2019-07-08 20:39 UTC (permalink / raw)
  To: Paolo Bonzini, Jim Mattson, Liran Alon, KarimAllah Ahmed, kvm

Hi all,

it seems the "new" KVM_SET_NESTED_STATE interface has some remaining
robustness issues. The most urgent one: With the help of latest QEMU
master that uses this interface, you can easily crash the host. You just
need to start qemu-system-x86 -enable-kvm in L1 and then hard-reset L1.
The host CPU that ran this will stall, the system will freeze soon.

I've also seen a pattern with my Jailhouse test VM where I seems to get
stuck in a loop between L1 and L2:

 qemu-system-x86-6660  [007]   398.691401: kvm_nested_vmexit:    rip 7fa9ee5224e4 reason IO_INSTRUCTION info1 5658000b info2 0 int_info 0 int_info_err 0
 qemu-system-x86-6660  [007]   398.691402: kvm_fpu:              unload
 qemu-system-x86-6660  [007]   398.691403: kvm_userspace_exit:   reason KVM_EXIT_IO (2)
 qemu-system-x86-6660  [007]   398.691440: kvm_fpu:              load
 qemu-system-x86-6660  [007]   398.691441: kvm_pio:              pio_read at 0x5658 size 4 count 1 val 0x4 
 qemu-system-x86-6660  [007]   398.691443: kvm_mmu_get_page:     existing sp gfn 3a22e 1/4 q3 direct --x !pge !nxe root 6 sync
 qemu-system-x86-6660  [007]   398.691444: kvm_entry:            vcpu 3
 qemu-system-x86-6660  [007]   398.691475: kvm_exit:             reason IO_INSTRUCTION rip 0x7fa9ee5224e4 info 5658000b 0
 qemu-system-x86-6660  [007]   398.691476: kvm_nested_vmexit:    rip 7fa9ee5224e4 reason IO_INSTRUCTION info1 5658000b info2 0 int_info 0 int_info_err 0
 qemu-system-x86-6660  [007]   398.691477: kvm_fpu:              unload
 qemu-system-x86-6660  [007]   398.691478: kvm_userspace_exit:   reason KVM_EXIT_IO (2)
 qemu-system-x86-6660  [007]   398.691526: kvm_fpu:              load
 qemu-system-x86-6660  [007]   398.691527: kvm_pio:              pio_read at 0x5658 size 4 count 1 val 0x4 
 qemu-system-x86-6660  [007]   398.691529: kvm_mmu_get_page:     existing sp gfn 3a22e 1/4 q3 direct --x !pge !nxe root 6 sync
 qemu-system-x86-6660  [007]   398.691530: kvm_entry:            vcpu 3
 qemu-system-x86-6660  [007]   398.691533: kvm_exit:             reason IO_INSTRUCTION rip 0x7fa9ee5224e4 info 5658000b 0
 qemu-system-x86-6660  [007]   398.691534: kvm_nested_vmexit:    rip 7fa9ee5224e4 reason IO_INSTRUCTION info1 5658000b info2 0 int_info 0 int_info_err 0

These issues disappear when going from ebbfef2f back to 6cfd7639 (both
with build fixes) in QEMU. Host kernels tested: 5.1.16 (distro) and 5.2
(vanilla).

Jan

-- 
Siemens AG, Corporate Technology, CT RDA IOT SES-DE
Corporate Competence Center Embedded Linux

^ permalink raw reply	[flat|nested] 10+ messages in thread

end of thread, other threads:[~2019-07-22 15:10 UTC | newest]

Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-07-08 20:39 KVM_SET_NESTED_STATE not yet stable Jan Kiszka
2019-07-10 15:24 ` Raslan, KarimAllah
2019-07-10 16:05   ` Jan Kiszka
2019-07-10 20:31     ` Jan Kiszka
2019-07-10 21:14       ` Jan Kiszka
2019-07-11 11:37       ` Ralf Ramsauer
2019-07-11 17:30         ` Paolo Bonzini
2019-07-19 16:38           ` Paolo Bonzini
2019-07-21  9:05             ` Jan Kiszka
2019-07-22 15:10               ` Ralf Ramsauer

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