* [stable-4.14/4.15] KVM: x86: fix backward migration with async_PF
@ 2018-03-09 13:20 Jack Wang
2018-03-09 14:43 ` Paolo Bonzini
0 siblings, 1 reply; 3+ messages in thread
From: Jack Wang @ 2018-03-09 13:20 UTC (permalink / raw)
To: stable, gregkh; +Cc: Radim Krčmář, Paolo Bonzini, Jack Wang
From: Radim Krčmář <rkrcmar@redhat.com>
commit fe2a3027e74e40a3ece3a4c1e4e51403090a907a upstream.
Guests on new hypersiors might set KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT
bit when enabling async_PF, but this bit is reserved on old hypervisors,
which results in a failure upon migration.
To avoid breaking different cases, we are checking for CPUID feature bit
before enabling the feature and nothing else.
Fixes: 52a5c155cf79 ("KVM: async_pf: Let guest support delivery of async_pf from guest mode")
Cc: <stable@vger.kernel.org>
Reviewed-by: Wanpeng Li <wanpengli@tencent.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
[jwang: port to 4.14]
Signed-off-by: Jack Wang <jinpu.wang@profitbricks.com>
---
Documentation/virtual/kvm/cpuid.txt | 4 ++++
Documentation/virtual/kvm/msr.txt | 3 ++-
arch/x86/include/uapi/asm/kvm_para.h | 1 +
arch/x86/kernel/kvm.c | 8 ++++----
arch/x86/kvm/cpuid.c | 3 ++-
5 files changed, 13 insertions(+), 6 deletions(-)
diff --git a/Documentation/virtual/kvm/cpuid.txt b/Documentation/virtual/kvm/cpuid.txt
index 3c65feb..a81c97a 100644
--- a/Documentation/virtual/kvm/cpuid.txt
+++ b/Documentation/virtual/kvm/cpuid.txt
@@ -54,6 +54,10 @@ KVM_FEATURE_PV_UNHALT || 7 || guest checks this feature bit
|| || before enabling paravirtualized
|| || spinlock support.
------------------------------------------------------------------------------
+KVM_FEATURE_ASYNC_PF_VMEXIT || 10 || paravirtualized async PF VM exit
+ || || can be enabled by setting bit 2
+ || || when writing to msr 0x4b564d02
+------------------------------------------------------------------------------
KVM_FEATURE_CLOCKSOURCE_STABLE_BIT || 24 || host will warn if no guest-side
|| || per-cpu warps are expected in
|| || kvmclock.
diff --git a/Documentation/virtual/kvm/msr.txt b/Documentation/virtual/kvm/msr.txt
index 1ebecc1..f3f0d57 100644
--- a/Documentation/virtual/kvm/msr.txt
+++ b/Documentation/virtual/kvm/msr.txt
@@ -170,7 +170,8 @@ MSR_KVM_ASYNC_PF_EN: 0x4b564d02
when asynchronous page faults are enabled on the vcpu 0 when
disabled. Bit 1 is 1 if asynchronous page faults can be injected
when vcpu is in cpl == 0. Bit 2 is 1 if asynchronous page faults
- are delivered to L1 as #PF vmexits.
+ are delivered to L1 as #PF vmexits. Bit 2 can be set only if
+ KVM_FEATURE_ASYNC_PF_VMEXIT is present in CPUID.
First 4 byte of 64 byte memory location will be written to by
the hypervisor at the time of asynchronous page fault (APF)
diff --git a/arch/x86/include/uapi/asm/kvm_para.h b/arch/x86/include/uapi/asm/kvm_para.h
index 09cc064..989db88 100644
--- a/arch/x86/include/uapi/asm/kvm_para.h
+++ b/arch/x86/include/uapi/asm/kvm_para.h
@@ -25,6 +25,7 @@
#define KVM_FEATURE_STEAL_TIME 5
#define KVM_FEATURE_PV_EOI 6
#define KVM_FEATURE_PV_UNHALT 7
+#define KVM_FEATURE_ASYNC_PF_VMEXIT 10
/* The last 8 bits are used to indicate how to interpret the flags field
* in pvclock structure. If no bits are set, all flags are ignored.
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index b40ffbf..0a93e83b 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -341,10 +341,10 @@ static void kvm_guest_cpu_init(void)
#endif
pa |= KVM_ASYNC_PF_ENABLED;
- /* Async page fault support for L1 hypervisor is optional */
- if (wrmsr_safe(MSR_KVM_ASYNC_PF_EN,
- (pa | KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT) & 0xffffffff, pa >> 32) < 0)
- wrmsrl(MSR_KVM_ASYNC_PF_EN, pa);
+ if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_VMEXIT))
+ pa |= KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT;
+
+ wrmsrl(MSR_KVM_ASYNC_PF_EN, pa);
__this_cpu_write(apf_reason.enabled, 1);
printk(KERN_INFO"KVM setup async PF for cpu %d\n",
smp_processor_id());
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 13f5d42..4f544f2 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -597,7 +597,8 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
(1 << KVM_FEATURE_ASYNC_PF) |
(1 << KVM_FEATURE_PV_EOI) |
(1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT) |
- (1 << KVM_FEATURE_PV_UNHALT);
+ (1 << KVM_FEATURE_PV_UNHALT) |
+ (1 << KVM_FEATURE_ASYNC_PF_VMEXIT);
if (sched_info_on())
entry->eax |= (1 << KVM_FEATURE_STEAL_TIME);
--
2.7.4
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [stable-4.14/4.15] KVM: x86: fix backward migration with async_PF
2018-03-09 13:20 [stable-4.14/4.15] KVM: x86: fix backward migration with async_PF Jack Wang
@ 2018-03-09 14:43 ` Paolo Bonzini
2018-03-09 14:48 ` Jinpu Wang
0 siblings, 1 reply; 3+ messages in thread
From: Paolo Bonzini @ 2018-03-09 14:43 UTC (permalink / raw)
To: Jack Wang, stable, gregkh; +Cc: Radim Krčmář
On 09/03/2018 14:20, Jack Wang wrote:
> From: Radim Krčmář <rkrcmar@redhat.com>
>
> commit fe2a3027e74e40a3ece3a4c1e4e51403090a907a upstream.
>
> Guests on new hypersiors might set KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT
> bit when enabling async_PF, but this bit is reserved on old hypervisors,
> which results in a failure upon migration.
>
> To avoid breaking different cases, we are checking for CPUID feature bit
> before enabling the feature and nothing else.
>
> Fixes: 52a5c155cf79 ("KVM: async_pf: Let guest support delivery of async_pf from guest mode")
> Cc: <stable@vger.kernel.org>
> Reviewed-by: Wanpeng Li <wanpengli@tencent.com>
> Reviewed-by: David Hildenbrand <david@redhat.com>
> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> [jwang: port to 4.14]
> Signed-off-by: Jack Wang <jinpu.wang@profitbricks.com>
> ---
> Documentation/virtual/kvm/cpuid.txt | 4 ++++
> Documentation/virtual/kvm/msr.txt | 3 ++-
> arch/x86/include/uapi/asm/kvm_para.h | 1 +
> arch/x86/kernel/kvm.c | 8 ++++----
> arch/x86/kvm/cpuid.c | 3 ++-
> 5 files changed, 13 insertions(+), 6 deletions(-)
>
> diff --git a/Documentation/virtual/kvm/cpuid.txt b/Documentation/virtual/kvm/cpuid.txt
> index 3c65feb..a81c97a 100644
> --- a/Documentation/virtual/kvm/cpuid.txt
> +++ b/Documentation/virtual/kvm/cpuid.txt
> @@ -54,6 +54,10 @@ KVM_FEATURE_PV_UNHALT || 7 || guest checks this feature bit
> || || before enabling paravirtualized
> || || spinlock support.
> ------------------------------------------------------------------------------
> +KVM_FEATURE_ASYNC_PF_VMEXIT || 10 || paravirtualized async PF VM exit
> + || || can be enabled by setting bit 2
> + || || when writing to msr 0x4b564d02
> +------------------------------------------------------------------------------
> KVM_FEATURE_CLOCKSOURCE_STABLE_BIT || 24 || host will warn if no guest-side
> || || per-cpu warps are expected in
> || || kvmclock.
> diff --git a/Documentation/virtual/kvm/msr.txt b/Documentation/virtual/kvm/msr.txt
> index 1ebecc1..f3f0d57 100644
> --- a/Documentation/virtual/kvm/msr.txt
> +++ b/Documentation/virtual/kvm/msr.txt
> @@ -170,7 +170,8 @@ MSR_KVM_ASYNC_PF_EN: 0x4b564d02
> when asynchronous page faults are enabled on the vcpu 0 when
> disabled. Bit 1 is 1 if asynchronous page faults can be injected
> when vcpu is in cpl == 0. Bit 2 is 1 if asynchronous page faults
> - are delivered to L1 as #PF vmexits.
> + are delivered to L1 as #PF vmexits. Bit 2 can be set only if
> + KVM_FEATURE_ASYNC_PF_VMEXIT is present in CPUID.
>
> First 4 byte of 64 byte memory location will be written to by
> the hypervisor at the time of asynchronous page fault (APF)
> diff --git a/arch/x86/include/uapi/asm/kvm_para.h b/arch/x86/include/uapi/asm/kvm_para.h
> index 09cc064..989db88 100644
> --- a/arch/x86/include/uapi/asm/kvm_para.h
> +++ b/arch/x86/include/uapi/asm/kvm_para.h
> @@ -25,6 +25,7 @@
> #define KVM_FEATURE_STEAL_TIME 5
> #define KVM_FEATURE_PV_EOI 6
> #define KVM_FEATURE_PV_UNHALT 7
> +#define KVM_FEATURE_ASYNC_PF_VMEXIT 10
>
> /* The last 8 bits are used to indicate how to interpret the flags field
> * in pvclock structure. If no bits are set, all flags are ignored.
> diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
> index b40ffbf..0a93e83b 100644
> --- a/arch/x86/kernel/kvm.c
> +++ b/arch/x86/kernel/kvm.c
> @@ -341,10 +341,10 @@ static void kvm_guest_cpu_init(void)
> #endif
> pa |= KVM_ASYNC_PF_ENABLED;
>
> - /* Async page fault support for L1 hypervisor is optional */
> - if (wrmsr_safe(MSR_KVM_ASYNC_PF_EN,
> - (pa | KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT) & 0xffffffff, pa >> 32) < 0)
> - wrmsrl(MSR_KVM_ASYNC_PF_EN, pa);
> + if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_VMEXIT))
> + pa |= KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT;
> +
> + wrmsrl(MSR_KVM_ASYNC_PF_EN, pa);
> __this_cpu_write(apf_reason.enabled, 1);
> printk(KERN_INFO"KVM setup async PF for cpu %d\n",
> smp_processor_id());
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index 13f5d42..4f544f2 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -597,7 +597,8 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
> (1 << KVM_FEATURE_ASYNC_PF) |
> (1 << KVM_FEATURE_PV_EOI) |
> (1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT) |
> - (1 << KVM_FEATURE_PV_UNHALT);
> + (1 << KVM_FEATURE_PV_UNHALT) |
> + (1 << KVM_FEATURE_ASYNC_PF_VMEXIT);
>
> if (sched_info_on())
> entry->eax |= (1 << KVM_FEATURE_STEAL_TIME);
>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Thanks Jack!
Paolo
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [stable-4.14/4.15] KVM: x86: fix backward migration with async_PF
2018-03-09 14:43 ` Paolo Bonzini
@ 2018-03-09 14:48 ` Jinpu Wang
0 siblings, 0 replies; 3+ messages in thread
From: Jinpu Wang @ 2018-03-09 14:48 UTC (permalink / raw)
To: Paolo Bonzini; +Cc: stable, Greg Kroah-Hartman, Radim Krčmář
On Fri, Mar 9, 2018 at 3:43 PM, Paolo Bonzini <pbonzini@redhat.com> wrote:
> On 09/03/2018 14:20, Jack Wang wrote:
>> From: Radim Krčmář <rkrcmar@redhat.com>
>>
>> commit fe2a3027e74e40a3ece3a4c1e4e51403090a907a upstream.
>>
>> Guests on new hypersiors might set KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT
>> bit when enabling async_PF, but this bit is reserved on old hypervisors,
>> which results in a failure upon migration.
>>
>> To avoid breaking different cases, we are checking for CPUID feature bit
>> before enabling the feature and nothing else.
>>
>> Fixes: 52a5c155cf79 ("KVM: async_pf: Let guest support delivery of async_pf from guest mode")
>> Cc: <stable@vger.kernel.org>
>> Reviewed-by: Wanpeng Li <wanpengli@tencent.com>
>> Reviewed-by: David Hildenbrand <david@redhat.com>
>> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
>> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
>> [jwang: port to 4.14]
>> Signed-off-by: Jack Wang <jinpu.wang@profitbricks.com>
>> ---
>> Documentation/virtual/kvm/cpuid.txt | 4 ++++
>> Documentation/virtual/kvm/msr.txt | 3 ++-
>> arch/x86/include/uapi/asm/kvm_para.h | 1 +
>> arch/x86/kernel/kvm.c | 8 ++++----
>> arch/x86/kvm/cpuid.c | 3 ++-
>> 5 files changed, 13 insertions(+), 6 deletions(-)
>>
>> diff --git a/Documentation/virtual/kvm/cpuid.txt b/Documentation/virtual/kvm/cpuid.txt
>> index 3c65feb..a81c97a 100644
>> --- a/Documentation/virtual/kvm/cpuid.txt
>> +++ b/Documentation/virtual/kvm/cpuid.txt
>> @@ -54,6 +54,10 @@ KVM_FEATURE_PV_UNHALT || 7 || guest checks this feature bit
>> || || before enabling paravirtualized
>> || || spinlock support.
>> ------------------------------------------------------------------------------
>> +KVM_FEATURE_ASYNC_PF_VMEXIT || 10 || paravirtualized async PF VM exit
>> + || || can be enabled by setting bit 2
>> + || || when writing to msr 0x4b564d02
>> +------------------------------------------------------------------------------
>> KVM_FEATURE_CLOCKSOURCE_STABLE_BIT || 24 || host will warn if no guest-side
>> || || per-cpu warps are expected in
>> || || kvmclock.
>> diff --git a/Documentation/virtual/kvm/msr.txt b/Documentation/virtual/kvm/msr.txt
>> index 1ebecc1..f3f0d57 100644
>> --- a/Documentation/virtual/kvm/msr.txt
>> +++ b/Documentation/virtual/kvm/msr.txt
>> @@ -170,7 +170,8 @@ MSR_KVM_ASYNC_PF_EN: 0x4b564d02
>> when asynchronous page faults are enabled on the vcpu 0 when
>> disabled. Bit 1 is 1 if asynchronous page faults can be injected
>> when vcpu is in cpl == 0. Bit 2 is 1 if asynchronous page faults
>> - are delivered to L1 as #PF vmexits.
>> + are delivered to L1 as #PF vmexits. Bit 2 can be set only if
>> + KVM_FEATURE_ASYNC_PF_VMEXIT is present in CPUID.
>>
>> First 4 byte of 64 byte memory location will be written to by
>> the hypervisor at the time of asynchronous page fault (APF)
>> diff --git a/arch/x86/include/uapi/asm/kvm_para.h b/arch/x86/include/uapi/asm/kvm_para.h
>> index 09cc064..989db88 100644
>> --- a/arch/x86/include/uapi/asm/kvm_para.h
>> +++ b/arch/x86/include/uapi/asm/kvm_para.h
>> @@ -25,6 +25,7 @@
>> #define KVM_FEATURE_STEAL_TIME 5
>> #define KVM_FEATURE_PV_EOI 6
>> #define KVM_FEATURE_PV_UNHALT 7
>> +#define KVM_FEATURE_ASYNC_PF_VMEXIT 10
>>
>> /* The last 8 bits are used to indicate how to interpret the flags field
>> * in pvclock structure. If no bits are set, all flags are ignored.
>> diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
>> index b40ffbf..0a93e83b 100644
>> --- a/arch/x86/kernel/kvm.c
>> +++ b/arch/x86/kernel/kvm.c
>> @@ -341,10 +341,10 @@ static void kvm_guest_cpu_init(void)
>> #endif
>> pa |= KVM_ASYNC_PF_ENABLED;
>>
>> - /* Async page fault support for L1 hypervisor is optional */
>> - if (wrmsr_safe(MSR_KVM_ASYNC_PF_EN,
>> - (pa | KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT) & 0xffffffff, pa >> 32) < 0)
>> - wrmsrl(MSR_KVM_ASYNC_PF_EN, pa);
>> + if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_VMEXIT))
>> + pa |= KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT;
>> +
>> + wrmsrl(MSR_KVM_ASYNC_PF_EN, pa);
>> __this_cpu_write(apf_reason.enabled, 1);
>> printk(KERN_INFO"KVM setup async PF for cpu %d\n",
>> smp_processor_id());
>> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
>> index 13f5d42..4f544f2 100644
>> --- a/arch/x86/kvm/cpuid.c
>> +++ b/arch/x86/kvm/cpuid.c
>> @@ -597,7 +597,8 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
>> (1 << KVM_FEATURE_ASYNC_PF) |
>> (1 << KVM_FEATURE_PV_EOI) |
>> (1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT) |
>> - (1 << KVM_FEATURE_PV_UNHALT);
>> + (1 << KVM_FEATURE_PV_UNHALT) |
>> + (1 << KVM_FEATURE_ASYNC_PF_VMEXIT);
>>
>> if (sched_info_on())
>> entry->eax |= (1 << KVM_FEATURE_STEAL_TIME);
>>
>
> Acked-by: Paolo Bonzini <pbonzini@redhat.com>
>
> Thanks Jack!
>
> Paolo
Thanks Paolo!
Jack
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2018-03-09 14:48 UTC | newest]
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2018-03-09 13:20 [stable-4.14/4.15] KVM: x86: fix backward migration with async_PF Jack Wang
2018-03-09 14:43 ` Paolo Bonzini
2018-03-09 14:48 ` Jinpu Wang
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