• Paul Mackerras's avatar
    KVM: PPC: Book3S HV: Enable TM before accessing TM registers · 805f79fe
    Paul Mackerras authored
    commit e4705715 upstream.
    
    Commit 46a704f8 ("KVM: PPC: Book3S HV: Preserve userspace HTM state
    properly", 2017-06-15) added code to read transactional memory (TM)
    registers but forgot to enable TM before doing so.  The result is
    that if userspace does have live values in the TM registers, a KVM_RUN
    ioctl will cause a host kernel crash like this:
    
    [  181.328511] Unrecoverable TM Unavailable Exception f60 at d00000001e7d9980
    [  181.328605] Oops: Unrecoverable TM Unavailable Exception, sig: 6 [#1]
    [  181.328613] SMP NR_CPUS=2048
    [  181.328613] NUMA
    [  181.328618] PowerNV
    [  181.328646] Modules linked in: vhost_net vhost tap nfs_layout_nfsv41_files rpcsec_gss_krb5 nfsv4 dns_resolver nfs
    +fscache xt_CHECKSUM iptable_mangle ipt_MASQUERADE nf_nat_masquerade_ipv4 iptable_nat nf_nat_ipv4 nf_nat
    +nf_conntrack_ipv4 nf_defrag_ipv4 xt_conntrack nf_conntrack ipt_REJECT nf_reject_ipv4 tun ebtable_filter ebtables
    +ip6table_filter ip6_tables iptable_filter bridge stp llc kvm_hv kvm nfsd ses enclosure scsi_transport_sas ghash_generic
    +auth_rpcgss gf128mul xts sg ctr nfs_acl lockd vmx_crypto shpchp ipmi_powernv i2c_opal grace ipmi_devintf i2c_core
    +powernv_rng sunrpc ipmi_msghandler ibmpowernv uio_pdrv_genirq uio leds_powernv powernv_op_panel ip_tables xfs sd_mod
    +lpfc ipr bnx2x libata mdio ptp pps_core scsi_transport_fc libcrc32c dm_mirror dm_region_hash dm_log dm_mod
    [  181.329278] CPU: 40 PID: 9926 Comm: CPU 0/KVM Not tainted 4.12.0+ #1
    [  181.329337] task: c000003fc6980000 task.stack: c000003fe4d80000
    [  181.329396] NIP: d00000001e7d9980 LR: d00000001e77381c CTR: d00000001e7d98f0
    [  181.329465] REGS: c000003fe4d837e0 TRAP: 0f60   Not tainted  (4.12.0+)
    [  181.329523] MSR: 9000000000009033 <SF,HV,EE,ME,IR,DR,RI,LE>
    [  181.329527]   CR: 24022448  XER: 00000000
    [  181.329608] CFAR: d00000001e773818 SOFTE: 1
    [  181.329608] GPR00: d00000001e77381c c000003fe4d83a60 d00000001e7ef410 c000003fdcfe0000
    [  181.329608] GPR04: c000003fe4f00000 0000000000000000 0000000000000000 c000003fd7954800
    [  181.329608] GPR08: 0000000000000001 c000003fc6980000 0000000000000000 d00000001e7e2880
    [  181.329608] GPR12: d00000001e7d98f0 c000000007b19000 00000001295220e0 00007fffc0ce2090
    [  181.329608] GPR16: 0000010011886608 00007fff8c89f260 0000000000000001 00007fff8c080028
    [  181.329608] GPR20: 0000000000000000 00000100118500a6 0000010011850000 0000010011850000
    [  181.329608] GPR24: 00007fffc0ce1b48 0000010011850000 00000000d673b901 0000000000000000
    [  181.329608] GPR28: 0000000000000000 c000003fdcfe0000 c000003fdcfe0000 c000003fe4f00000
    [  181.330199] NIP [d00000001e7d9980] kvmppc_vcpu_run_hv+0x90/0x6b0 [kvm_hv]
    [  181.330264] LR [d00000001e77381c] kvmppc_vcpu_run+0x2c/0x40 [kvm]
    [  181.330322] Call Trace:
    [  181.330351] [c000003fe4d83a60] [d00000001e773478] kvmppc_set_one_reg+0x48/0x340 [kvm] (unreliable)
    [  181.330437] [c000003fe4d83b30] [d00000001e77381c] kvmppc_vcpu_run+0x2c/0x40 [kvm]
    [  181.330513] [c000003fe4d83b50] [d00000001e7700b4] kvm_arch_vcpu_ioctl_run+0x114/0x2a0 [kvm]
    [  181.330586] [c000003fe4d83bd0] [d00000001e7642f8] kvm_vcpu_ioctl+0x598/0x7a0 [kvm]
    [  181.330658] [c000003fe4d83d40] [c0000000003451b8] do_vfs_ioctl+0xc8/0x8b0
    [  181.330717] [c000003fe4d83de0] [c000000000345a64] SyS_ioctl+0xc4/0x120
    [  181.330776] [c000003fe4d83e30] [c00000000000b004] system_call+0x58/0x6c
    [  181.330833] Instruction dump:
    [  181.330869] e92d0260 e9290b50 e9290108 792807e3 41820058 e92d0260 e9290b50 e9290108
    [  181.330941] 792ae8a4 794a1f87 408204f4 e92d0260 <7d4022a6> f9490ff0 e92d0260 7d4122a6
    [  181.331013] ---[ end trace 6f6ddeb4bfe92a92 ]---
    
    The fix is just to turn on the TM bit in the MSR before accessing the
    registers.
    
    Fixes: 46a704f8 ("KVM: PPC: Book3S HV: Preserve userspace HTM state properly")
    Reported-by: default avatarJan Stancek <jstancek@redhat.com>
    Tested-by: default avatarJan Stancek <jstancek@redhat.com>
    Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    805f79fe
book3s_hv.c 103 KB