Re: [Qemu-devel] [PATCH 09/11] kvm/x86: distingiush hyper-v guest crash notification

[Paolo Bonzini]

On 22/06/2015 18:05, Denis V. Lunev wrote:
> From: Andrey Smetanin <address@hidden>
> 
> Previous patches allowes userspace to setup Hyper-V crash ctl msr.
> This msr should expose HV_X64_MSR_CRASH_CTL_NOTIFY value to Hyper-V
> guest to allow to send crash data. Unfortunately Hyper-V guest notifies
> hardware about crash by writing the same HV_X64_MSR_CRASH_CTL_NOTIFY value
> into crash ctl msr. Thus both user space and guest writes inside ctl msr the
> same value and this patch distingiush the moment of actual guest crash
> by checking host initiated value from msr info.
> 
> Signed-off-by: Andrey Smetanin <address@hidden>
> Signed-off-by: Denis V. Lunev <address@hidden>
> CC: Paolo Bonzini <address@hidden>
> CC: Gleb Natapov <address@hidden>
> ---
>  arch/x86/kvm/hyperv.c | 17 +++++++++--------
>  arch/x86/kvm/hyperv.h |  2 +-
>  arch/x86/kvm/x86.c    |  3 ++-
>  3 files changed, 12 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
> index 6b18015..f49502a 100644
> --- a/arch/x86/kvm/hyperv.c
> +++ b/arch/x86/kvm/hyperv.c
> @@ -54,12 +54,12 @@ static int kvm_hv_msr_get_crash_ctl(struct kvm_vcpu 
> *vcpu, u64 *pdata)
>       return 0;
>  }
>  
> -static int kvm_hv_msr_set_crash_ctl(struct kvm_vcpu *vcpu, u64 data)
> +static int kvm_hv_msr_set_crash_ctl(struct kvm_vcpu *vcpu, u64 data, bool 
> host)
>  {
>       struct kvm_arch_hyperv *hv = &vcpu->kvm->arch.hyperv;
>  
>       hv->hv_crash_ctl = data;
> -     if ((data & HV_X64_MSR_CRASH_CTL_NOTIFY)) {
> +     if ((data & HV_X64_MSR_CRASH_CTL_NOTIFY) && !host) {
>               vcpu_debug(vcpu, "hv crash (0x%llx 0x%llx 0x%llx 0x%llx "
>                         "0x%llx)\n", hv->hv_crash_param[0],
>                         hv->hv_crash_param[1],
> @@ -99,7 +99,8 @@ static int kvm_hv_msr_get_crash_data(struct kvm_vcpu *vcpu,
>       return 0;
>  }
>  
> -static int kvm_hv_set_msr_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data)
> +static int kvm_hv_set_msr_pw(struct kvm_vcpu *vcpu,
> +                          u32 msr, u64 data, bool host)
>  {
>       struct kvm *kvm = vcpu->kvm;
>       struct kvm_arch_hyperv *hv = &kvm->arch.hyperv;
> @@ -156,7 +157,7 @@ static int kvm_hv_set_msr_pw(struct kvm_vcpu *vcpu, u32 
> msr, u64 data)
>                                                msr - HV_X64_MSR_CRASH_P0,
>                                                data);
>       case HV_X64_MSR_CRASH_CTL:
> -             return kvm_hv_msr_set_crash_ctl(vcpu, data);
> +             return kvm_hv_msr_set_crash_ctl(vcpu, data, host);
>       default:
>               vcpu_unimpl(vcpu, "Hyper-V unimpl wrmsr: 0x%x data 0x%llx\n",
>                                 msr, data);
> @@ -165,7 +166,7 @@ static int kvm_hv_set_msr_pw(struct kvm_vcpu *vcpu, u32 
> msr, u64 data)
>       return 0;
>  }
>  
> -static int kvm_hv_set_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data)
> +static int kvm_hv_set_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data, bool 
> host)
>  {
>       struct kvm_vcpu_arch_hyperv *hv = &vcpu->arch.hyperv;
>  
> @@ -278,17 +279,17 @@ static int kvm_hv_get_msr(struct kvm_vcpu *vcpu, u32 
> msr, u64 *pdata)
>       return 0;
>  }
>  
> -int kvm_hv_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
> +int kvm_hv_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data, bool 
> host)
>  {
>       if (kvm_hv_msr_partition_wide(msr)) {
>               int r;
>  
>               mutex_lock(&vcpu->kvm->lock);
> -             r = kvm_hv_set_msr_pw(vcpu, msr, data);
> +             r = kvm_hv_set_msr_pw(vcpu, msr, data, host);
>               mutex_unlock(&vcpu->kvm->lock);
>               return r;
>       } else
> -             return kvm_hv_set_msr(vcpu, msr, data);
> +             return kvm_hv_set_msr(vcpu, msr, data, host);
>  }
>  
>  int kvm_hv_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
> diff --git a/arch/x86/kvm/hyperv.h b/arch/x86/kvm/hyperv.h
> index 39aee93..dc49527 100644
> --- a/arch/x86/kvm/hyperv.h
> +++ b/arch/x86/kvm/hyperv.h
> @@ -22,7 +22,7 @@
>  #ifndef __ARCH_X86_KVM_HYPERV_H__
>  #define __ARCH_X86_KVM_HYPERV_H__
>  
> -int kvm_hv_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data);
> +int kvm_hv_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data, bool 
> host);
>  int kvm_hv_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata);
>  
>  bool kvm_hv_hypercall_enabled(struct kvm *kvm);
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 111fa83..db4eecb 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -2210,7 +2210,8 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct 
> msr_data *msr_info)
>       case HV_X64_MSR_GUEST_OS_ID ... HV_X64_MSR_SINT15:
>       case HV_X64_MSR_CRASH_P0 ... HV_X64_MSR_CRASH_P4:
>       case HV_X64_MSR_CRASH_CTL:
> -             return kvm_hv_set_msr_common(vcpu, msr, data);
> +             return kvm_hv_set_msr_common(vcpu, msr, data,
> +                                          msr_info->host_initiated);
>               break;
>       case MSR_IA32_BBL_CR_CTL3:
>               /* Drop writes to this legacy MSR -- see rdmsr
> 

This has to be squashed into patch 7.  The patches looked good so far,
so I can do this myself, but I'm dropping a note here in case I find
something on a second read and you need to do a v3.

Paolo