Re: [nVMX] With 3.20.0-0.rc0.git5.1 on L0, booting L2 guest results in L1 *rebooting*

[Kashyap Chamarthy <kchamart@redhat.com>]

Tested with the _correct_ Kernel[1] (that has Radim's patch) now --
applied it on both L0 and L1.

Result: Same as before -- Booting L2 causes L1 to reboot. However, the
        stack trace from `dmesg` on L0 is took slightly different path than
        before -- it's using MSR handling:

. . .
[Feb23 12:14] ------------[ cut here ]------------
[  +0.004658] WARNING: CPU: 5 PID: 1785 at arch/x86/kvm/vmx.c:9973 nested_vmx_vmexit+0xbde/0xd30 [kvm_intel]()
[  +0.009897] Modules linked in: vhost_net vhost macvtap macvlan xt_CHECKSUM iptable_mangle ipt_MASQUERADE nf_nat_masquerade_ipv4 iptable_nat nf_nat_ipv4 nf_nat nf_conntrack_ipv4 nf_defrag_i
pv4 xt_conntrack nf_conntrack tun bridge stp llc ebtable_filter ebtables ip6table_filter ip6_tables iTCO_wdt ipmi_devintf gpio_ich iTCO_vendor_support coretemp kvm_intel dcdbas kvm crc32c_in
tel joydev ipmi_ssif serio_raw ipmi_si tpm_tis i7core_edac lpc_ich ipmi_msghandler edac_core tpm mfd_core shpchp wmi acpi_power_meter acpi_cpufreq nfsd auth_rpcgss nfs_acl lockd grace sunrpc
 mgag200 i2c_algo_bit drm_kms_helper ttm ata_generic drm pata_acpi megaraid_sas bnx2
[  +0.060790] CPU: 5 PID: 1785 Comm: qemu-system-x86 Not tainted 3.20.0-0.rc0.git9.1.fc23.x86_64 #1
[  +0.008938] Hardware name: Dell Inc. PowerEdge R910/0P658H, BIOS 2.8.2 10/25/2012
[  +0.007476]  0000000000000000 000000008ba15f99 ffff88ff5d627b38 ffffffff818773cd
[  +0.007727]  0000000000000000 0000000000000000 ffff88ff5d627b78 ffffffff810ab3ba
[  +0.007660]  ffff88ff5d627b68 ffff883f5fd20000 0000000000000000 0000000000000000
[  +0.007729] Call Trace:
[  +0.002543]  [<ffffffff818773cd>] dump_stack+0x4c/0x65
[  +0.005205]  [<ffffffff810ab3ba>] warn_slowpath_common+0x8a/0xc0
[  +0.006085]  [<ffffffff810ab4ea>] warn_slowpath_null+0x1a/0x20
[  +0.005915]  [<ffffffffa0244f8e>] nested_vmx_vmexit+0xbde/0xd30 [kvm_intel]
[  +0.007061]  [<ffffffffa0245976>] vmx_set_msr+0x416/0x420 [kvm_intel]
[  +0.006549]  [<ffffffffa029f0c0>] ? kvm_set_msr+0x70/0x70 [kvm]
[  +0.006018]  [<ffffffffa029f091>] kvm_set_msr+0x41/0x70 [kvm]
[  +0.005840]  [<ffffffffa029f0f3>] do_set_msr+0x33/0x50 [kvm]
[  +0.005692]  [<ffffffffa02a3a80>] msr_io+0x100/0x1c0 [kvm]
[  +0.005567]  [<ffffffffa02a3a10>] ? msr_io+0x90/0x1c0 [kvm]
[  +0.005657]  [<ffffffffa023de70>] ? handle_task_switch+0x1f0/0x1f0 [kvm_intel]
[  +0.007321]  [<ffffffffa02ac799>] kvm_arch_vcpu_ioctl+0xb79/0x11a0 [kvm]
[  +0.006788]  [<ffffffffa023f7fe>] ? vmx_vcpu_load+0x15e/0x1e0 [kvm_intel]
[  +0.006878]  [<ffffffffa0298666>] ? vcpu_load+0x26/0x70 [kvm]
[  +0.005825]  [<ffffffffa02abac3>] ? kvm_arch_vcpu_load+0xb3/0x210 [kvm]
[  +0.006712]  [<ffffffffa02987da>] kvm_vcpu_ioctl+0xea/0x7e0 [kvm]
[  +0.006140]  [<ffffffff81027b9d>] ? native_sched_clock+0x2d/0xa0
[  +0.006063]  [<ffffffff810d5c56>] ? creds_are_invalid.part.1+0x16/0x50
[  +0.006583]  [<ffffffff810d5cb1>] ? creds_are_invalid+0x21/0x30
[  +0.005984]  [<ffffffff813a77fa>] ? inode_has_perm.isra.48+0x2a/0xa0
[  +0.006436]  [<ffffffff8128c9a8>] do_vfs_ioctl+0x2e8/0x530
[  +0.005559]  [<ffffffff8128cc71>] SyS_ioctl+0x81/0xa0
[  +0.005135]  [<ffffffff81880969>] system_call_fastpath+0x12/0x17
[  +0.006065] ---[ end trace a7f3bc31fb0ddbff ]---
. . .


[1] https://kashyapc.fedorapeople.org/kernel-3.20.0-0.rc0.git9.1.fc23.rpms-with-nvmx-test-fix-from-radim/
     - I uploaded the Fedora Koji scratch build for this Kernel to a
       more permanant location, as these type of builds will be removed
       automatically after 3 weeks

-- 
/kashyap