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| Started by | Wanpeng Li <kernellwp@gmail.com> |
|---|---|
| First post | 2017-06-29 05:10 +0200 |
| Last post | 2017-06-29 14:20 +0200 |
| Articles | 3 — 2 participants |
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[PATCH v7 0/4] KVM: async_pf: Fix async pf exception injection Wanpeng Li <kernellwp@gmail.com> - 2017-06-29 05:10 +0200
Re: [PATCH v7 0/4] KVM: async_pf: Fix async pf exception injection Wanpeng Li <kernellwp@gmail.com> - 2017-06-29 09:20 +0200
Re: [PATCH v7 0/4] KVM: async_pf: Fix async pf exception injection Paolo Bonzini <pbonzini@redhat.com> - 2017-06-29 14:20 +0200
| From | Wanpeng Li <kernellwp@gmail.com> |
|---|---|
| Date | 2017-06-29 05:10 +0200 |
| Subject | [PATCH v7 0/4] KVM: async_pf: Fix async pf exception injection |
| Message-ID | <tXy0a-29p-5@gated-at.bofh.it> |
INFO: task gnome-terminal-:1734 blocked for more than 120 seconds.
Not tainted 4.12.0-rc4+ #8
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
gnome-terminal- D 0 1734 1015 0x00000000
Call Trace:
__schedule+0x3cd/0xb30
schedule+0x40/0x90
kvm_async_pf_task_wait+0x1cc/0x270
? __vfs_read+0x37/0x150
? prepare_to_swait+0x22/0x70
do_async_page_fault+0x77/0xb0
? do_async_page_fault+0x77/0xb0
async_page_fault+0x28/0x30
This is triggered by running both win7 and win2016 on L1 KVM simultaneously,
and then gives stress to memory on L1, I can observed this hang on L1 when
at least ~70% swap area is occupied on L0.
This is due to async pf was injected to L2 which should be injected to L1,
L2 guest starts receiving pagefault w/ bogus %cr2(apf token from the host
actually), and L1 guest starts accumulating tasks stuck in D state in
kvm_async_pf_task_wait() since missing PAGE_READY async_pfs.
This patchset fixes it according to Radim's proposal "force a nested VM exit
from nested_vmx_check_exception if the injected #PF is async_pf and handle
the #PF VM exit in L1". https://www.spinics.net/lists/kvm/msg142498.html
v6 -> v7:
* drop KVM_GET/PUT_VCPU_EVENTS stuff for nested_apf
v5 -> v6:
* move vcpu_svm's apf_reason to vcpu->arch.apf.host_apf_reason
* introduce function kvm_handle_page_fault() to be used by both VMX/SVM
* introduce svm's codes posted by Paolo
* introduce nested_apf
* better set MSR_KVM_ASYNC_PF_EN
v4 -> v5:
* utilize wrmsr_safe for MSR_KVM_ASYNC_PF_EN
v3 -> v4:
* reuse pad field in kvm_vcpu_events for async_page_fault
* update kvm_vcpu_events API documentations
* change async_page_fault type in vcpu->arch.exception from bool to u8
v2 -> v3:
* add the flag to the userspace interface(KVM_GET/PUT_VCPU_EVENTS)
v1 -> v2:
* remove nested_vmx_check_exception nr parameter
* construct a simple special vm-exit information field for async pf
* introduce nested_apf_token to vcpu->arch.apf to avoid change the CR2
visible in L2 guest
* avoid pass the apf directed towards it (L1) into L2 if there is L3
at the moment
Wanpeng Li (4):
KVM: x86: Simple kvm_x86_ops->queue_exception parameter
KVM: async_pf: Add L1 guest async_pf #PF vmexit handler
KVM: async_pf: Force a nested vmexit if the injected #PF is async_pf
KVM: async_pf: Let host know whether the guest support delivery async_pf as #PF vmexit
Documentation/virtual/kvm/msr.txt | 5 ++--
arch/x86/include/asm/kvm_emulate.h | 1 +
arch/x86/include/asm/kvm_host.h | 8 +++--
arch/x86/include/uapi/asm/kvm_para.h | 1 +
arch/x86/kernel/kvm.c | 7 ++++-
arch/x86/kvm/mmu.c | 35 +++++++++++++++++++++-
arch/x86/kvm/mmu.h | 2 ++
arch/x86/kvm/svm.c | 58 ++++++++++++------------------------
arch/x86/kvm/vmx.c | 39 +++++++++++++++---------
arch/x86/kvm/x86.c | 19 +++++++-----
10 files changed, 108 insertions(+), 67 deletions(-)
--
2.7.4
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| From | Wanpeng Li <kernellwp@gmail.com> |
|---|---|
| Date | 2017-06-29 09:20 +0200 |
| Message-ID | <tXBU8-4BD-35@gated-at.bofh.it> |
| In reply to | #1677335 |
2017-06-29 11:01 GMT+08:00 Wanpeng Li <kernellwp@gmail.com>:
> INFO: task gnome-terminal-:1734 blocked for more than 120 seconds.
> Not tainted 4.12.0-rc4+ #8
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> gnome-terminal- D 0 1734 1015 0x00000000
> Call Trace:
> __schedule+0x3cd/0xb30
> schedule+0x40/0x90
> kvm_async_pf_task_wait+0x1cc/0x270
> ? __vfs_read+0x37/0x150
> ? prepare_to_swait+0x22/0x70
> do_async_page_fault+0x77/0xb0
> ? do_async_page_fault+0x77/0xb0
> async_page_fault+0x28/0x30
>
> This is triggered by running both win7 and win2016 on L1 KVM simultaneously,
> and then gives stress to memory on L1, I can observed this hang on L1 when
> at least ~70% swap area is occupied on L0.
>
> This is due to async pf was injected to L2 which should be injected to L1,
> L2 guest starts receiving pagefault w/ bogus %cr2(apf token from the host
> actually), and L1 guest starts accumulating tasks stuck in D state in
> kvm_async_pf_task_wait() since missing PAGE_READY async_pfs.
>
> This patchset fixes it according to Radim's proposal "force a nested VM exit
> from nested_vmx_check_exception if the injected #PF is async_pf and handle
> the #PF VM exit in L1". https://www.spinics.net/lists/kvm/msg142498.html
Note: The patchset depends on commit d4912215d10 ("KVM: nVMX: Fix
exception injection") and commit 9bc1f09f6fa76fd (KVM: async_pf: avoid
async pf injection when in guest mode) on the master branch.
Regards,
Wanpeng Li
>
> v6 -> v7:
> * drop KVM_GET/PUT_VCPU_EVENTS stuff for nested_apf
>
> v5 -> v6:
> * move vcpu_svm's apf_reason to vcpu->arch.apf.host_apf_reason
> * introduce function kvm_handle_page_fault() to be used by both VMX/SVM
> * introduce svm's codes posted by Paolo
> * introduce nested_apf
> * better set MSR_KVM_ASYNC_PF_EN
>
> v4 -> v5:
> * utilize wrmsr_safe for MSR_KVM_ASYNC_PF_EN
>
> v3 -> v4:
> * reuse pad field in kvm_vcpu_events for async_page_fault
> * update kvm_vcpu_events API documentations
> * change async_page_fault type in vcpu->arch.exception from bool to u8
>
> v2 -> v3:
> * add the flag to the userspace interface(KVM_GET/PUT_VCPU_EVENTS)
>
> v1 -> v2:
> * remove nested_vmx_check_exception nr parameter
> * construct a simple special vm-exit information field for async pf
> * introduce nested_apf_token to vcpu->arch.apf to avoid change the CR2
> visible in L2 guest
> * avoid pass the apf directed towards it (L1) into L2 if there is L3
> at the moment
>
> Wanpeng Li (4):
> KVM: x86: Simple kvm_x86_ops->queue_exception parameter
> KVM: async_pf: Add L1 guest async_pf #PF vmexit handler
> KVM: async_pf: Force a nested vmexit if the injected #PF is async_pf
> KVM: async_pf: Let host know whether the guest support delivery async_pf as #PF vmexit
>
> Documentation/virtual/kvm/msr.txt | 5 ++--
> arch/x86/include/asm/kvm_emulate.h | 1 +
> arch/x86/include/asm/kvm_host.h | 8 +++--
> arch/x86/include/uapi/asm/kvm_para.h | 1 +
> arch/x86/kernel/kvm.c | 7 ++++-
> arch/x86/kvm/mmu.c | 35 +++++++++++++++++++++-
> arch/x86/kvm/mmu.h | 2 ++
> arch/x86/kvm/svm.c | 58 ++++++++++++------------------------
> arch/x86/kvm/vmx.c | 39 +++++++++++++++---------
> arch/x86/kvm/x86.c | 19 +++++++-----
> 10 files changed, 108 insertions(+), 67 deletions(-)
>
> --
> 2.7.4
>
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| From | Paolo Bonzini <pbonzini@redhat.com> |
|---|---|
| Date | 2017-06-29 14:20 +0200 |
| Message-ID | <tXGAq-7t8-17@gated-at.bofh.it> |
| In reply to | #1677469 |
On 29/06/2017 09:13, Wanpeng Li wrote:
>> This patchset fixes it according to Radim's proposal "force a nested VM exit
>> from nested_vmx_check_exception if the injected #PF is async_pf and handle
>> the #PF VM exit in L1". https://www.spinics.net/lists/kvm/msg142498.html
>
> Note: The patchset depends on commit d4912215d10 ("KVM: nVMX: Fix
> exception injection") and commit 9bc1f09f6fa76fd (KVM: async_pf: avoid
> async pf injection when in guest mode) on the master branch.
Thanks for reminding me. I'll wait for the merge window before applying
it, but it looks good.
Paolo
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