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[PATCH 1/2] KVM: lapic: fix access preemption timer stuff even if kernel_irqchip=off

Started byWanpeng Li <kernellwp@gmail.com>
First post2016-08-03 06:10 +0200
Last post2016-08-04 14:30 +0200
Articles 6 — 3 participants

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  [PATCH 1/2] KVM: lapic: fix access preemption timer stuff even if kernel_irqchip=off Wanpeng Li <kernellwp@gmail.com> - 2016-08-03 06:10 +0200
    [PATCH 2/2] KVM: lapic: don't recalculate apic map table twice when enabling LAPIC Wanpeng Li <kernellwp@gmail.com> - 2016-08-03 06:10 +0200
      Re: [PATCH 2/2] KVM: lapic: don't recalculate apic map table twice  when enabling LAPIC Radim Krčmář <rkrcmar@redhat.com> - 2016-08-03 12:00 +0200
    Re: [PATCH 1/2] KVM: lapic: fix access preemption timer stuff even  if kernel_irqchip=off Radim Krčmář <rkrcmar@redhat.com> - 2016-08-03 12:20 +0200
      Re: [PATCH 1/2] KVM: lapic: fix access preemption timer stuff even if kernel_irqchip=off Wanpeng Li <kernellwp@gmail.com> - 2016-08-03 13:00 +0200
    Re: [PATCH 1/2] KVM: lapic: fix access preemption timer stuff even if  kernel_irqchip=off Paolo Bonzini <pbonzini@redhat.com> - 2016-08-04 14:30 +0200

#1455619 — [PATCH 1/2] KVM: lapic: fix access preemption timer stuff even if kernel_irqchip=off

FromWanpeng Li <kernellwp@gmail.com>
Date2016-08-03 06:10 +0200
Subject[PATCH 1/2] KVM: lapic: fix access preemption timer stuff even if kernel_irqchip=off
Message-ID<s1VFf-5Kv-3@gated-at.bofh.it>
From: Wanpeng Li <wanpeng.li@hotmail.com>

BUG: unable to handle kernel NULL pointer dereference at 000000000000008c
IP: [<ffffffffc04e0180>] kvm_lapic_hv_timer_in_use+0x10/0x20 [kvm]
PGD 0 
Oops: 0000 [#1] SMP
Call Trace:
 kvm_arch_vcpu_load+0x86/0x260 [kvm]
 vcpu_load+0x46/0x60 [kvm]
 kvm_vcpu_ioctl+0x79/0x7c0 [kvm]
 ? __lock_is_held+0x54/0x70
 do_vfs_ioctl+0x96/0x6a0
 ? __fget_light+0x2a/0x90
 SyS_ioctl+0x79/0x90
 do_syscall_64+0x7c/0x1e0
 entry_SYSCALL64_slow_path+0x25/0x25
RIP  [<ffffffffc04e0180>] kvm_lapic_hv_timer_in_use+0x10/0x20 [kvm]
 RSP <ffff8800db1f3d70>
CR2: 000000000000008c
---[ end trace a55fb79d2b3b4ee8 ]---

This can be reproduced steadily by kernel_irqchip=off.

We should not access preemption timer stuff if lapic is emulated in userspace.
This patch fix it by avoiding access preemption timer stuff when kernel_irqchip=off.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Yunhong Jiang <yunhong.jiang@intel.com>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
---
 arch/x86/kvm/lapic.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 6895fd2..0120a58 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1348,6 +1348,9 @@ static void start_sw_tscdeadline(struct kvm_lapic *apic)
 
 bool kvm_lapic_hv_timer_in_use(struct kvm_vcpu *vcpu)
 {
+	if (!lapic_in_kernel(vcpu))
+		return false;
+
 	return vcpu->arch.apic->lapic_timer.hv_timer_in_use;
 }
 EXPORT_SYMBOL_GPL(kvm_lapic_hv_timer_in_use);
-- 
1.9.1

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#1455622 — [PATCH 2/2] KVM: lapic: don't recalculate apic map table twice when enabling LAPIC

FromWanpeng Li <kernellwp@gmail.com>
Date2016-08-03 06:10 +0200
Subject[PATCH 2/2] KVM: lapic: don't recalculate apic map table twice when enabling LAPIC
Message-ID<s1VFf-5Kv-17@gated-at.bofh.it>
In reply to#1455619
From: Wanpeng Li <wanpeng.li@hotmail.com>

APIC map table is recalculated during reset APIC ID to the initial value
when enabling LAPIC. This patch move the recalculate_apic_map() to the 
next branch since we don't need to recalculate apic map twice in current
codes.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
---
 arch/x86/kvm/lapic.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 0120a58..d676f4b 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1760,9 +1760,10 @@ void kvm_lapic_set_base(struct kvm_vcpu *vcpu, u64 value)
 		if (value & MSR_IA32_APICBASE_ENABLE) {
 			kvm_apic_set_xapic_id(apic, vcpu->vcpu_id);
 			static_key_slow_dec_deferred(&apic_hw_disabled);
-		} else
+		} else {
 			static_key_slow_inc(&apic_hw_disabled.key);
-		recalculate_apic_map(vcpu->kvm);
+			recalculate_apic_map(vcpu->kvm);
+		}
 	}
 
 	if ((old_value ^ value) & X2APIC_ENABLE) {
-- 
1.9.1

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#1455716 — Re: [PATCH 2/2] KVM: lapic: don't recalculate apic map table twice when enabling LAPIC

FromRadim Krčmář <rkrcmar@redhat.com>
Date2016-08-03 12:00 +0200
SubjectRe: [PATCH 2/2] KVM: lapic: don't recalculate apic map table twice when enabling LAPIC
Message-ID<s217X-Sn-3@gated-at.bofh.it>
In reply to#1455622
2016-08-03 12:04+0800, Wanpeng Li:
> From: Wanpeng Li <wanpeng.li@hotmail.com>
> 
> APIC map table is recalculated during reset APIC ID to the initial value
> when enabling LAPIC. This patch move the recalculate_apic_map() to the 
> next branch since we don't need to recalculate apic map twice in current
> codes.
> 
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Radim Krčmář <rkrcmar@redhat.com>
> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
> ---

Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>

> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> @@ -1760,9 +1760,10 @@ void kvm_lapic_set_base(struct kvm_vcpu *vcpu, u64 value)
>  		if (value & MSR_IA32_APICBASE_ENABLE) {
>  			kvm_apic_set_xapic_id(apic, vcpu->vcpu_id);
>  			static_key_slow_dec_deferred(&apic_hw_disabled);
> -		} else
> +		} else {
>  			static_key_slow_inc(&apic_hw_disabled.key);
> -		recalculate_apic_map(vcpu->kvm);
> +			recalculate_apic_map(vcpu->kvm);
> +		}
>  	}
>  
>  	if ((old_value ^ value) & X2APIC_ENABLE) {
> -- 
> 1.9.1
>

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#1455720 — Re: [PATCH 1/2] KVM: lapic: fix access preemption timer stuff even if kernel_irqchip=off

FromRadim Krčmář <rkrcmar@redhat.com>
Date2016-08-03 12:20 +0200
SubjectRe: [PATCH 1/2] KVM: lapic: fix access preemption timer stuff even if kernel_irqchip=off
Message-ID<s21rj-1e7-1@gated-at.bofh.it>
In reply to#1455619
2016-08-03 12:04+0800, Wanpeng Li:
> From: Wanpeng Li <wanpeng.li@hotmail.com>
> 
> BUG: unable to handle kernel NULL pointer dereference at 000000000000008c
> IP: [<ffffffffc04e0180>] kvm_lapic_hv_timer_in_use+0x10/0x20 [kvm]
> PGD 0 
> Oops: 0000 [#1] SMP
> Call Trace:
>  kvm_arch_vcpu_load+0x86/0x260 [kvm]
>  vcpu_load+0x46/0x60 [kvm]
>  kvm_vcpu_ioctl+0x79/0x7c0 [kvm]
>  ? __lock_is_held+0x54/0x70
>  do_vfs_ioctl+0x96/0x6a0
>  ? __fget_light+0x2a/0x90
>  SyS_ioctl+0x79/0x90
>  do_syscall_64+0x7c/0x1e0
>  entry_SYSCALL64_slow_path+0x25/0x25
> RIP  [<ffffffffc04e0180>] kvm_lapic_hv_timer_in_use+0x10/0x20 [kvm]
>  RSP <ffff8800db1f3d70>
> CR2: 000000000000008c
> ---[ end trace a55fb79d2b3b4ee8 ]---
> 
> This can be reproduced steadily by kernel_irqchip=off.
> 
> We should not access preemption timer stuff if lapic is emulated in userspace.
> This patch fix it by avoiding access preemption timer stuff when kernel_irqchip=off.
> 
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Radim Krčmář <rkrcmar@redhat.com>
> Cc: Yunhong Jiang <yunhong.jiang@intel.com>
> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
> ---

Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>

> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> @@ -1348,6 +1348,9 @@ static void start_sw_tscdeadline(struct kvm_lapic *apic)
>  
>  bool kvm_lapic_hv_timer_in_use(struct kvm_vcpu *vcpu)

Btw, the "hv" in makes it look like it has something to do with Hyper-V.
What does "hv" stand for anyway?  Hardware Virtualized?

Thanks.

>  {
> +	if (!lapic_in_kernel(vcpu))
> +		return false;
> +
>  	return vcpu->arch.apic->lapic_timer.hv_timer_in_use;
>  }
>  EXPORT_SYMBOL_GPL(kvm_lapic_hv_timer_in_use);

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#1455744

FromWanpeng Li <kernellwp@gmail.com>
Date2016-08-03 13:00 +0200
Message-ID<s2242-1tn-11@gated-at.bofh.it>
In reply to#1455720
2016-08-03 17:55 GMT+08:00 Radim Krčmář <rkrcmar@redhat.com>:
> 2016-08-03 12:04+0800, Wanpeng Li:
>> From: Wanpeng Li <wanpeng.li@hotmail.com>
>>
>> BUG: unable to handle kernel NULL pointer dereference at 000000000000008c
>> IP: [<ffffffffc04e0180>] kvm_lapic_hv_timer_in_use+0x10/0x20 [kvm]
>> PGD 0
>> Oops: 0000 [#1] SMP
>> Call Trace:
>>  kvm_arch_vcpu_load+0x86/0x260 [kvm]
>>  vcpu_load+0x46/0x60 [kvm]
>>  kvm_vcpu_ioctl+0x79/0x7c0 [kvm]
>>  ? __lock_is_held+0x54/0x70
>>  do_vfs_ioctl+0x96/0x6a0
>>  ? __fget_light+0x2a/0x90
>>  SyS_ioctl+0x79/0x90
>>  do_syscall_64+0x7c/0x1e0
>>  entry_SYSCALL64_slow_path+0x25/0x25
>> RIP  [<ffffffffc04e0180>] kvm_lapic_hv_timer_in_use+0x10/0x20 [kvm]
>>  RSP <ffff8800db1f3d70>
>> CR2: 000000000000008c
>> ---[ end trace a55fb79d2b3b4ee8 ]---
>>
>> This can be reproduced steadily by kernel_irqchip=off.
>>
>> We should not access preemption timer stuff if lapic is emulated in userspace.
>> This patch fix it by avoiding access preemption timer stuff when kernel_irqchip=off.
>>
>> Cc: Paolo Bonzini <pbonzini@redhat.com>
>> Cc: Radim Krčmář <rkrcmar@redhat.com>
>> Cc: Yunhong Jiang <yunhong.jiang@intel.com>
>> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
>> ---
>
> Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>
>
>> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
>> @@ -1348,6 +1348,9 @@ static void start_sw_tscdeadline(struct kvm_lapic *apic)
>>
>>  bool kvm_lapic_hv_timer_in_use(struct kvm_vcpu *vcpu)
>
> Btw, the "hv" in makes it look like it has something to do with Hyper-V.
> What does "hv" stand for anyway?  Hardware Virtualized?

Hmm, yeah, hv_timer make people confusing.
http://www.spinics.net/lists/kvm/msg134205.html

Regards,
Wanpeng Li

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#1456372 — Re: [PATCH 1/2] KVM: lapic: fix access preemption timer stuff even if kernel_irqchip=off

FromPaolo Bonzini <pbonzini@redhat.com>
Date2016-08-04 14:30 +0200
SubjectRe: [PATCH 1/2] KVM: lapic: fix access preemption timer stuff even if kernel_irqchip=off
Message-ID<s2pWG-yi-25@gated-at.bofh.it>
In reply to#1455619

On 03/08/2016 06:04, Wanpeng Li wrote:
> From: Wanpeng Li <wanpeng.li@hotmail.com>
> 
> BUG: unable to handle kernel NULL pointer dereference at 000000000000008c
> IP: [<ffffffffc04e0180>] kvm_lapic_hv_timer_in_use+0x10/0x20 [kvm]
> PGD 0 
> Oops: 0000 [#1] SMP
> Call Trace:
>  kvm_arch_vcpu_load+0x86/0x260 [kvm]
>  vcpu_load+0x46/0x60 [kvm]
>  kvm_vcpu_ioctl+0x79/0x7c0 [kvm]
>  ? __lock_is_held+0x54/0x70
>  do_vfs_ioctl+0x96/0x6a0
>  ? __fget_light+0x2a/0x90
>  SyS_ioctl+0x79/0x90
>  do_syscall_64+0x7c/0x1e0
>  entry_SYSCALL64_slow_path+0x25/0x25
> RIP  [<ffffffffc04e0180>] kvm_lapic_hv_timer_in_use+0x10/0x20 [kvm]
>  RSP <ffff8800db1f3d70>
> CR2: 000000000000008c
> ---[ end trace a55fb79d2b3b4ee8 ]---
> 
> This can be reproduced steadily by kernel_irqchip=off.
> 
> We should not access preemption timer stuff if lapic is emulated in userspace.
> This patch fix it by avoiding access preemption timer stuff when kernel_irqchip=off.
> 
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Radim Krčmář <rkrcmar@redhat.com>
> Cc: Yunhong Jiang <yunhong.jiang@intel.com>
> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
> ---
>  arch/x86/kvm/lapic.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index 6895fd2..0120a58 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -1348,6 +1348,9 @@ static void start_sw_tscdeadline(struct kvm_lapic *apic)
>  
>  bool kvm_lapic_hv_timer_in_use(struct kvm_vcpu *vcpu)
>  {
> +	if (!lapic_in_kernel(vcpu))
> +		return false;
> +
>  	return vcpu->arch.apic->lapic_timer.hv_timer_in_use;
>  }
>  EXPORT_SYMBOL_GPL(kvm_lapic_hv_timer_in_use);
> 

Applied patch 1, while 2 will wait for 4.9.

Paolo

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