Hi Christoffer
On 12/14/2017 9:09 PM, Christoffer Dall Wrote:
On Thu, Dec 14, 2017 at 12:57:54PM +0800, Jia He wrote:
Hi Jia,
I have tried your newer level-mapped-v7 branch, but bug is still there.
There is no special load in both host and guest. The guest (kernel
4.14) is often hanging when booting
the guest kernel log
[ OK ] Reached target Remote File Systems.
Starting File System Check on /dev/mapper/fedora-root...
[ OK ] Started File System Check on /dev/mapper/fedora-root.
Mounting /sysroot...
[ 2.670764] SGI XFS with ACLs, security attributes, no debug enabled
[ 2.678180] XFS (dm-0): Mounting V5 Filesystem
[ 2.740364] XFS (dm-0): Ending clean mount
[ OK ] Mounted /sysroot.
[ OK ] Reached target Initrd Root File System.
Starting Reload Configuration from the Real Root...
[ 61.288215] INFO: rcu_sched detected stalls on CPUs/tasks:
[ 61.290791] 1-...!: (0 ticks this GP) idle=574/0/0 softirq=5/5 fqs=1
[ 61.293664] (detected by 0, t=6002 jiffies, g=-263, c=-264, q=39760)
[ 61.296480] Task dump for CPU 1:
[ 61.297938] swapper/1 R running task 0 0 1 0x00000020
[ 61.300643] Call trace:
[ 61.301260] __switch_to+0x6c/0x78
[ 61.302095] cpu_number+0x0/0x8
[ 61.302867] rcu_sched kthread starved for 6000 jiffies!
g18446744073709551353 c18446744073709551352 f0x0 RCU_GP_WAIT_FQS(3)
->state=0x402 ->cpu=1
[ 61.305941] rcu_sched I 0 8 2 0x00000020
[ 61.307250] Call trace:
[ 61.307854] __switch_to+0x6c/0x78
[ 61.308693] __schedule+0x268/0x8f0
[ 61.309545] schedule+0x2c/0x88
[ 61.310325] schedule_timeout+0x84/0x3b8
[ 61.311278] rcu_gp_kthread+0x4d4/0x7d8
[ 61.312213] kthread+0x134/0x138
[ 61.313001] ret_from_fork+0x10/0x1c
Maybe my previous patch is not perfect enough, thanks for your comments.
I digged it futher more, do you think below code logic is possibly
problematic?
vtimer_save_state (vtimer->loaded = false, cntv_ctl is 0)
kvm_arch_timer_handler (read cntv_ctl and set vtimer->cnt_ctl = 0)
vtimer_restore_state (write vtimer->cnt_ctl to cntv_ctl,
then cntv_ctl will
be 0 forever)
If above analysis is reasonable
Yes, I think there's something there if the hardware doesn't retire the
signal fast enough...
how about below patch? already
tested in my arm64 server.
diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
index f9555b1..ee6dd3f 100644
--- a/virt/kvm/arm/arch_timer.c
+++ b/virt/kvm/arm/arch_timer.c
@@ -99,7 +99,7 @@ static irqreturn_t kvm_arch_timer_handler(int irq,
void *dev_id)
}
vtimer = vcpu_vtimer(vcpu);
- if (!vtimer->irq.level) {
+ if (vtimer->loaded && !vtimer->irq.level) {
vtimer->cnt_ctl = read_sysreg_el0(cntv_ctl);
if (kvm_timer_irq_can_fire(vtimer))
kvm_timer_update_irq(vcpu, true, vtimer);
There's nothing really wrong with that patch, I just didn't think it
would be necessary, as we really shouldn't see interrupts if the timer
is not loaded. Can you confirm that a WARN_ON(!vtimer->loaded) in
kvm_arch_timer_handler() gives you a splat?
Please see the WARN_ON result (without my patch)
[ 72.171706] WARNING: CPU: 24 PID: 1768 at
arch/arm64/kvm/../../../virt/kvm/arm/arch_timer.c:101
kvm_arch_timer_handler+0xc0/0xc8
[ 72.182305] Modules linked in: vhost_net tap 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 xt_tcpudp bridge stp llc
ebtable_filter ebtables ip6table_filter ip6_tables iptable_filter
ip_tables x_tables vhost_scsi vhost tcm_qla2xxx qla2xxx nvme_fc
nvme_fabrics tcm_fc libfc scsi_transport_fc ib_srpt ib_cm ib_core
iscsi_target_mod tcm_loop target_core_file target_core_iblock
target_core_pscsi target_core_mod binfmt_misc nls_iso8859_1 shpchp
crc32_ce crct10dif_ce i2c_qup dm_multipath autofs4 btrfs zstd_decompress
zstd_compress xxhash raid10 raid456 async_raid6_recov async_memcpy
async_pq async_xor async_tx xor raid6_pq libcrc32c raid1 raid0 multipath
linear at803x ixgbe
[ 72.252877] xhci_plat_hcd xhci_hcd usbcore qcom_emac mdio
ahci_platform libahci_platform libahci
[ 72.261733] CPU: 24 PID: 1768 Comm: qemu-system-aar Tainted: G
W 4.15.0-rc3+ #128
[ 72.270412] Hardware name: WIWYNN QDF2400 Reference Evaluation
Platform CV90-LA115-P151/QDF2400 Customer Reference Board, BIOS 0ACJA425
09/07/2017
[ 72.283520] pstate: 80400085 (Nzcv daIf +PAN -UAO)
[ 72.288295] pc : kvm_arch_timer_handler+0xc0/0xc8
[ 72.292984] lr : handle_percpu_devid_irq+0x8c/0x230
[ 72.297842] sp : ffff00000830ff00
[ 72.301141] x29: ffff00000830ff00 x28: ffffc17b9feaff00
[ 72.306436] x27: ffff2e7462531000 x26: ffff000008310000
[ 72.311731] x25: ffff000008300000 x24: ffffc17b80069100
[ 72.317026] x23: 0000000000000003 x22: ffff2e74632248e8
[ 72.322321] x21: ffffc17b80054c00 x20: 0000000000000000
[ 72.327616] x19: ffffc17b8ac37dc0 x18: 0000000000000010
[ 72.332911] x17: 000000000000000a x16: 0000000000007fff
[ 72.338207] x15: ffffffffffffffff x14: 6d202c6666666666
[ 72.343502] x13: 6666667830203a73 x12: 656c6379635f7861
[ 72.348797] x11: ffff000009395448 x10: ffff00000862b5b8
[ 72.354092] x9 : 0000000000000040 x8 : ffffc17b60007238
[ 72.359387] x7 : 0000000000000000 x6 : ffffc17b80054c00
[ 72.364682] x5 : ffffc17b60007250 x4 : 0000930756ce0000
[ 72.369977] x3 : ffff2e74619cfff0 x2 : 0000930756ce0000
[ 72.375273] x1 : 0000000000000000 x0 : ffffc17b8ac399c0
[ 72.380568] Call trace:
[ 72.383000] kvm_arch_timer_handler+0xc0/0xc8
[ 72.387340] handle_percpu_devid_irq+0x8c/0x230
[ 72.391853] generic_handle_irq+0x34/0x50
[ 72.395846] __handle_domain_irq+0x68/0xc0
[ 72.399926] gic_handle_irq+0xcc/0x188
[ 72.403658] el1_irq+0xd8/0x180
[ 72.406785] hrtimer_try_to_cancel+0x0/0x160
[ 72.411037] kvm_timer_vcpu_put+0x3c/0x50
[ 72.415030] kvm_arch_vcpu_put+0x20/0x50
[ 72.418937] vcpu_put+0x20/0x40
[ 72.422061] kvm_vcpu_ioctl+0x244/0x7b8
[ 72.425882] do_vfs_ioctl+0xc4/0x988
[ 72.429440] SyS_ioctl+0x94/0xa8
[ 72.432652] el0_svc_naked+0x20/0x24
[ 72.436210] ---[ end trace 11d0c8bba284e766 ]---
Also, could you give the following a try (without your patch):
diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
index 73d262c4712b..4751255345d1 100644
--- a/virt/kvm/arm/arch_timer.c
+++ b/virt/kvm/arm/arch_timer.c
@@ -367,6 +367,7 @@ static void vtimer_save_state(struct kvm_vcpu *vcpu)
/* Disable the virtual timer */
write_sysreg_el0(0, cntv_ctl);
+ isb();
No luck， the bug is still there
Cheers,
Jia
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