This is a note to let you know that I've just added the patch titled KVM: PPC: Book3S HV: Enable TM before accessing TM registers to the 3.18-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: kvm-ppc-book3s-hv-enable-tm-before-accessing-tm-registers.patch and it can be found in the queue-3.18 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From e47057151422a67ce08747176fa21cb3b526a2c9 Mon Sep 17 00:00:00 2001 From: Paul Mackerras <paulus@xxxxxxxxxx> Date: Fri, 21 Jul 2017 13:57:14 +1000 Subject: KVM: PPC: Book3S HV: Enable TM before accessing TM registers From: Paul Mackerras <paulus@xxxxxxxxxx> commit e47057151422a67ce08747176fa21cb3b526a2c9 upstream. Commit 46a704f8409f ("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: 46a704f8409f ("KVM: PPC: Book3S HV: Preserve userspace HTM state properly") Reported-by: Jan Stancek <jstancek@xxxxxxxxxx> Tested-by: Jan Stancek <jstancek@xxxxxxxxxx> Signed-off-by: Paul Mackerras <paulus@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/powerpc/kvm/book3s_hv.c | 2 ++ 1 file changed, 2 insertions(+) --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -1971,6 +1971,8 @@ static int kvmppc_vcpu_run_hv(struct kvm run->fail_entry.hardware_entry_failure_reason = 0; return -EINVAL; } + /* Enable TM so we can read the TM SPRs */ + mtmsr(mfmsr() | MSR_TM); current->thread.tm_tfhar = mfspr(SPRN_TFHAR); current->thread.tm_tfiar = mfspr(SPRN_TFIAR); current->thread.tm_texasr = mfspr(SPRN_TEXASR); Patches currently in stable-queue which might be from paulus@xxxxxxxxxx are queue-3.18/kvm-ppc-book3s-hv-enable-tm-before-accessing-tm-registers.patch