Re: [PATCH v3 00/26] KVM: x86: Halt and APICv overhaul

Maxim Levitsky
2021-12-08T23:01:02Z

On Wed, 2021-12-08 at 01:52 +0000, Sean Christopherson wrote:
> Overhaul and cleanup APIC virtualization (Posted Interrupts on Intel VMX,
> AVIC on AMD SVM) to streamline things as much as possible, remove a bunch
> of cruft, and document the lurking gotchas along the way.
>
> Patch 01 is a fix from Paolo that's already been merged but hasn't made
> its way to kvm/queue. It's included here to avoid a number of conflicts.
>
> Based on kvm/queue, commit 1cf84614b04a ("KVM: x86: Exit to ...")
>
> v3:
> - Rebase to kvm/queue (and drop non-x86 patches as they've been queued).
> - Redo AVIC patches, sadly the vcpu_(un)blocking() hooks need to stay.
> - Add a patch to fix a missing (docuentation-only) barrier in nested
> posted interrupt delivery. [Paolo]
> - Collect reviews.
>
> v2:
> - https://lore.kernel.org/all/20211009021236.4122790-1-seanjc@google.com/
> - Collect reviews. [Christian, David]
> - Add patch to move arm64 WFI functionality out of hooks. [Marc]
> - Add RISC-V to the fun.
> - Add all the APICv fun.
>
> v1: https://lkml.kernel.org/r/20210925005528.1145584-1-seanjc@google.com
>
> Paolo Bonzini (1):
> KVM: fix avic_set_running for preemptable kernels
>
> Sean Christopherson (25):
> KVM: nVMX: Ensure vCPU honors event request if posting nested IRQ
> fails
> KVM: VMX: Clean up PI pre/post-block WARNs
> KVM: VMX: Handle PI wakeup shenanigans during vcpu_put/load
> KVM: Drop unused kvm_vcpu.pre_pcpu field
> KVM: Move x86 VMX's posted interrupt list_head to vcpu_vmx
> KVM: VMX: Move preemption timer <=> hrtimer dance to common x86
> KVM: x86: Unexport LAPIC's switch_to_{hv,sw}_timer() helpers
> KVM: x86: Remove defunct pre_block/post_block kvm_x86_ops hooks
> KVM: SVM: Signal AVIC doorbell iff vCPU is in guest mode
> KVM: SVM: Don't bother checking for "running" AVIC when kicking for
> IPIs
> KVM: SVM: Remove unnecessary APICv/AVIC update in vCPU unblocking path
> KVM: SVM: Use kvm_vcpu_is_blocking() in AVIC load to handle preemption
> KVM: SVM: Skip AVIC and IRTE updates when loading blocking vCPU
> iommu/amd: KVM: SVM: Use pCPU to infer IsRun state for IRTE
> KVM: VMX: Don't do full kick when triggering posted interrupt "fails"
> KVM: VMX: Wake vCPU when delivering posted IRQ even if vCPU == this
> vCPU
> KVM: VMX: Pass desired vector instead of bool for triggering posted
> IRQ
> KVM: VMX: Fold fallback path into triggering posted IRQ helper
> KVM: VMX: Don't do full kick when handling posted interrupt wakeup
> KVM: SVM: Drop AVIC's intermediate avic_set_running() helper
> KVM: SVM: Move svm_hardware_setup() and its helpers below svm_x86_ops
> KVM: SVM: Nullify vcpu_(un)blocking() hooks if AVIC is disabled
> KVM: x86: Skip APICv update if APICv is disable at the module level
> KVM: x86: Drop NULL check on kvm_x86_ops.check_apicv_inhibit_reasons
> KVM: x86: Unexport __kvm_request_apicv_update()
>
> arch/x86/include/asm/kvm-x86-ops.h | 2 -
> arch/x86/include/asm/kvm_host.h | 12 -
> arch/x86/kvm/hyperv.c | 3 +
> arch/x86/kvm/lapic.c | 2 -
> arch/x86/kvm/svm/avic.c | 116 ++++---
> arch/x86/kvm/svm/svm.c | 479 ++++++++++++++---------------
> arch/x86/kvm/svm/svm.h | 16 +-
> arch/x86/kvm/vmx/posted_intr.c | 234 +++++++-------
> arch/x86/kvm/vmx/posted_intr.h | 8 +-
> arch/x86/kvm/vmx/vmx.c | 66 ++--
> arch/x86/kvm/vmx/vmx.h | 3 +
> arch/x86/kvm/x86.c | 41 ++-
> drivers/iommu/amd/iommu.c | 6 +-
> include/linux/amd-iommu.h | 6 +-
> include/linux/kvm_host.h | 3 -
> virt/kvm/kvm_main.c | 3 -
> 16 files changed, 510 insertions(+), 490 deletions(-)
>

Probably just luck (can't reproduce this anymore) but
while running some kvm unit tests with this patch series (and few my patches
for AVIC co-existance which shouldn't affect this) I got this

(warning about is_running already set)

Dec 08 22:53:26 amdlaptop kernel: ------------[ cut here ]------------
Dec 08 22:53:26 amdlaptop kernel: WARNING: CPU: 3 PID: 72804 at arch/x86/kvm/svm/avic.c:1045 avic_vcpu_load+0xe3/0x100 [kvm_amd]
Dec 08 22:53:26 amdlaptop kernel: Modules linked in: kvm_amd(O) ccp rng_core kvm(O) irqbypass xt_conntrack ip6table_filter ip6_tables snd_soc_dmic snd_acp3x_>
Dec 08 22:53:26 amdlaptop kernel: r8169 realtek 8250_pci usbmon nbd fuse autofs4 [last unloaded: rng_core]
Dec 08 22:53:26 amdlaptop kernel: CPU: 3 PID: 72804 Comm: qemu-system-i38 Tainted: G O 5.16.0-rc4.unstable #6
Dec 08 22:53:26 amdlaptop kernel: Hardware name: LENOVO 20UF001CUS/20UF001CUS, BIOS R1CET65W(1.34 ) 06/17/2021
Dec 08 22:53:26 amdlaptop kernel: RIP: 0010:avic_vcpu_load+0xe3/0x100 [kvm_amd]
Dec 08 22:53:26 amdlaptop kernel: Code: 0d 9f e0 85 c0 74 e8 4c 89 f6 4c 89 ff e8 a5 99 f4 e0 5b 41 5c 41 5d 41 5e 41 5f 5d c3 0f 0b 5b 41 5c 41 5d 41 5e 41 >
Dec 08 22:53:26 amdlaptop kernel: RSP: 0018:ffffc9000b17bba8 EFLAGS: 00010247
Dec 08 22:53:26 amdlaptop kernel: RAX: 6f63203a756d6571 RBX: ffff888106194740 RCX: ffff88812e7ac000
Dec 08 22:53:26 amdlaptop kernel: RDX: ffff8883ff6c0000 RSI: 0000000000000003 RDI: 0000000000000003
Dec 08 22:53:26 amdlaptop kernel: RBP: ffffc9000b17bbd0 R08: ffff888106194740 R09: 0000000000000000
Dec 08 22:53:26 amdlaptop kernel: R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000003
Dec 08 22:53:26 amdlaptop kernel: R13: 0000000000000003 R14: ffff88810023b060 R15: dead000000000100
Dec 08 22:53:26 amdlaptop kernel: FS: 0000000000000000(0000) GS:ffff8883ff6c0000(0000) knlGS:0000000000000000
Dec 08 22:53:26 amdlaptop kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Dec 08 22:53:26 amdlaptop kernel: CR2: 00005587e812f958 CR3: 0000000105f31000 CR4: 0000000000350ee0
Dec 08 22:53:26 amdlaptop kernel: DR0: 00000000004008da DR1: 0000000000000000 DR2: 0000000000000000
Dec 08 22:53:26 amdlaptop kernel: DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Dec 08 22:53:26 amdlaptop kernel: Call Trace:
Dec 08 22:53:26 amdlaptop kernel: <TASK>
Dec 08 22:53:26 amdlaptop kernel: svm_vcpu_load+0x56/0x60 [kvm_amd]
Dec 08 22:53:26 amdlaptop kernel: kvm_arch_vcpu_load+0x32/0x210 [kvm]
Dec 08 22:53:26 amdlaptop kernel: vcpu_load+0x34/0x40 [kvm]
Dec 08 22:53:26 amdlaptop kernel: kvm_arch_destroy_vm+0xd4/0x1c0 [kvm]
Dec 08 22:53:26 amdlaptop kernel: kvm_destroy_vm+0x163/0x250 [kvm]
Dec 08 22:53:26 amdlaptop kernel: kvm_put_kvm+0x26/0x40 [kvm]
Dec 08 22:53:26 amdlaptop kernel: kvm_vm_release+0x22/0x30 [kvm]
Dec 08 22:53:26 amdlaptop kernel: __fput+0x94/0x250
Dec 08 22:53:26 amdlaptop kernel: ____fput+0xe/0x10
Dec 08 22:53:26 amdlaptop kernel: task_work_run+0x63/0xa0
Dec 08 22:53:26 amdlaptop kernel: do_exit+0x358/0xa30
Dec 08 22:53:26 amdlaptop kernel: do_group_exit+0x3b/0xa0
Dec 08 22:53:26 amdlaptop kernel: get_signal+0x15b/0x880
Dec 08 22:53:26 amdlaptop kernel: ? _copy_to_user+0x20/0x30
Dec 08 22:53:26 amdlaptop kernel: ? put_timespec64+0x3d/0x60
Dec 08 22:53:26 amdlaptop kernel: arch_do_signal_or_restart+0x106/0x740
Dec 08 22:53:26 amdlaptop kernel: ? hrtimer_nanosleep+0x9f/0x120
Dec 08 22:53:26 amdlaptop kernel: ? __hrtimer_init+0xd0/0xd0
Dec 08 22:53:26 amdlaptop kernel: exit_to_user_mode_prepare+0x112/0x1f0
Dec 08 22:53:26 amdlaptop kernel: syscall_exit_to_user_mode+0x17/0x40
Dec 08 22:53:26 amdlaptop kernel: do_syscall_64+0x42/0x80
Dec 08 22:53:26 amdlaptop kernel: entry_SYSCALL_64_after_hwframe+0x44/0xae
Dec 08 22:53:26 amdlaptop kernel: RIP: 0033:0x7f537abb13b5
Dec 08 22:53:26 amdlaptop kernel: Code: Unable to access opcode bytes at RIP 0x7f537abb138b.
Dec 08 22:53:26 amdlaptop kernel: RSP: 002b:00007f5376a39680 EFLAGS: 00000293 ORIG_RAX: 00000000000000e6
Dec 08 22:53:26 amdlaptop kernel: RAX: fffffffffffffdfc RBX: 00007f5376a396d0 RCX: 00007f537abb13b5
Dec 08 22:53:26 amdlaptop kernel: RDX: 00007f5376a396d0 RSI: 0000000000000000 RDI: 0000000000000000
Dec 08 22:53:26 amdlaptop kernel: RBP: 00007f5376a396c0 R08: 0000000000000000 R09: 0000000000000000
Dec 08 22:53:26 amdlaptop kernel: R10: 00007f5376a396c0 R11: 0000000000000293 R12: 00007f5376a3b640
Dec 08 22:53:26 amdlaptop kernel: R13: 0000000000000002 R14: 00007f537ab66880 R15: 0000000000000000
Dec 08 22:53:26 amdlaptop kernel: </TASK>
Dec 08 22:53:26 amdlaptop kernel: ---[ end trace 676058aaf29d0267 ]---

I'll post my patches tomorrow, after some more testing.

Best regards,
Maxim Levitsky