| Message ID | 20180201211621.27371-1-rkrcmar@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
2018-02-02 5:16 GMT+08:00 Radim Krčmář <rkrcmar@redhat.com>: > 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> > Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> Reviewed-by: Wanpeng Li <wanpengli@tencent.com> > --- > v2: > * added documentation [Paolo] > * retained compatibility recent kernels [Paolo] > --- > 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 dcab6dc11e3b..87a7506f31c2 100644 > --- a/Documentation/virtual/kvm/cpuid.txt > +++ b/Documentation/virtual/kvm/cpuid.txt > @@ -58,6 +58,10 @@ KVM_FEATURE_PV_TLB_FLUSH || 9 || guest checks this feature bit > || || before enabling paravirtualized > || || tlb flush. > ------------------------------------------------------------------------------ > +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 1ebecc115dc6..f3f0d57ced8e 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 7a2ade4aa235..6cfa9c8cb7d6 100644 > --- a/arch/x86/include/uapi/asm/kvm_para.h > +++ b/arch/x86/include/uapi/asm/kvm_para.h > @@ -26,6 +26,7 @@ > #define KVM_FEATURE_PV_EOI 6 > #define KVM_FEATURE_PV_UNHALT 7 > #define KVM_FEATURE_PV_TLB_FLUSH 9 > +#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 4e37d1a851a6..971babe964d2 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 20e491b94f44..7fc04a176c57 100644 > --- a/arch/x86/kvm/cpuid.c > +++ b/arch/x86/kvm/cpuid.c > @@ -604,7 +604,8 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function, > (1 << KVM_FEATURE_PV_EOI) | > (1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT) | > (1 << KVM_FEATURE_PV_UNHALT) | > - (1 << KVM_FEATURE_PV_TLB_FLUSH); > + (1 << KVM_FEATURE_PV_TLB_FLUSH) | > + (1 << KVM_FEATURE_ASYNC_PF_VMEXIT); > > if (sched_info_on()) > entry->eax |= (1 << KVM_FEATURE_STEAL_TIME); > -- > 2.15.1 >
On 01.02.2018 22:16, Radim Krčmář wrote: > 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> > Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> > --- > v2: > * added documentation [Paolo] > * retained compatibility recent kernels [Paolo] > --- > 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 dcab6dc11e3b..87a7506f31c2 100644 > --- a/Documentation/virtual/kvm/cpuid.txt > +++ b/Documentation/virtual/kvm/cpuid.txt > @@ -58,6 +58,10 @@ KVM_FEATURE_PV_TLB_FLUSH || 9 || guest checks this feature bit > || || before enabling paravirtualized > || || tlb flush. > ------------------------------------------------------------------------------ > +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 1ebecc115dc6..f3f0d57ced8e 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 7a2ade4aa235..6cfa9c8cb7d6 100644 > --- a/arch/x86/include/uapi/asm/kvm_para.h > +++ b/arch/x86/include/uapi/asm/kvm_para.h > @@ -26,6 +26,7 @@ > #define KVM_FEATURE_PV_EOI 6 > #define KVM_FEATURE_PV_UNHALT 7 > #define KVM_FEATURE_PV_TLB_FLUSH 9 > +#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 4e37d1a851a6..971babe964d2 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 20e491b94f44..7fc04a176c57 100644 > --- a/arch/x86/kvm/cpuid.c > +++ b/arch/x86/kvm/cpuid.c > @@ -604,7 +604,8 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function, > (1 << KVM_FEATURE_PV_EOI) | > (1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT) | > (1 << KVM_FEATURE_PV_UNHALT) | > - (1 << KVM_FEATURE_PV_TLB_FLUSH); > + (1 << KVM_FEATURE_PV_TLB_FLUSH) | > + (1 << KVM_FEATURE_ASYNC_PF_VMEXIT); > > if (sched_info_on()) > entry->eax |= (1 << KVM_FEATURE_STEAL_TIME); > Reviewed-by: David Hildenbrand <david@redhat.com>
On 01/02/2018 22:16, Radim Krčmář wrote: > 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> > Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> > --- > v2: > * added documentation [Paolo] > * retained compatibility recent kernels [Paolo] > --- > 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 dcab6dc11e3b..87a7506f31c2 100644 > --- a/Documentation/virtual/kvm/cpuid.txt > +++ b/Documentation/virtual/kvm/cpuid.txt > @@ -58,6 +58,10 @@ KVM_FEATURE_PV_TLB_FLUSH || 9 || guest checks this feature bit > || || before enabling paravirtualized > || || tlb flush. > ------------------------------------------------------------------------------ > +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 1ebecc115dc6..f3f0d57ced8e 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 7a2ade4aa235..6cfa9c8cb7d6 100644 > --- a/arch/x86/include/uapi/asm/kvm_para.h > +++ b/arch/x86/include/uapi/asm/kvm_para.h > @@ -26,6 +26,7 @@ > #define KVM_FEATURE_PV_EOI 6 > #define KVM_FEATURE_PV_UNHALT 7 > #define KVM_FEATURE_PV_TLB_FLUSH 9 > +#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 4e37d1a851a6..971babe964d2 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 20e491b94f44..7fc04a176c57 100644 > --- a/arch/x86/kvm/cpuid.c > +++ b/arch/x86/kvm/cpuid.c > @@ -604,7 +604,8 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function, > (1 << KVM_FEATURE_PV_EOI) | > (1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT) | > (1 << KVM_FEATURE_PV_UNHALT) | > - (1 << KVM_FEATURE_PV_TLB_FLUSH); > + (1 << KVM_FEATURE_PV_TLB_FLUSH) | > + (1 << KVM_FEATURE_ASYNC_PF_VMEXIT); > > if (sched_info_on()) > entry->eax |= (1 << KVM_FEATURE_STEAL_TIME); > Queued, thanks. Paolo
diff --git a/Documentation/virtual/kvm/cpuid.txt b/Documentation/virtual/kvm/cpuid.txt index dcab6dc11e3b..87a7506f31c2 100644 --- a/Documentation/virtual/kvm/cpuid.txt +++ b/Documentation/virtual/kvm/cpuid.txt @@ -58,6 +58,10 @@ KVM_FEATURE_PV_TLB_FLUSH || 9 || guest checks this feature bit || || before enabling paravirtualized || || tlb flush. ------------------------------------------------------------------------------ +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 1ebecc115dc6..f3f0d57ced8e 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 7a2ade4aa235..6cfa9c8cb7d6 100644 --- a/arch/x86/include/uapi/asm/kvm_para.h +++ b/arch/x86/include/uapi/asm/kvm_para.h @@ -26,6 +26,7 @@ #define KVM_FEATURE_PV_EOI 6 #define KVM_FEATURE_PV_UNHALT 7 #define KVM_FEATURE_PV_TLB_FLUSH 9 +#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 4e37d1a851a6..971babe964d2 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 20e491b94f44..7fc04a176c57 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -604,7 +604,8 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function, (1 << KVM_FEATURE_PV_EOI) | (1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT) | (1 << KVM_FEATURE_PV_UNHALT) | - (1 << KVM_FEATURE_PV_TLB_FLUSH); + (1 << KVM_FEATURE_PV_TLB_FLUSH) | + (1 << KVM_FEATURE_ASYNC_PF_VMEXIT); if (sched_info_on()) entry->eax |= (1 << KVM_FEATURE_STEAL_TIME);
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> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> --- v2: * added documentation [Paolo] * retained compatibility recent kernels [Paolo] --- 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(-)