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

[Peter Hornyack]

On Mon, Jun 22, 2015 at 9:05 AM, Denis V. Lunev <address@hidden> 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;

Should we allow hv_crash_ctl to be set if !host? It's a small detail,
but it doesn't seem like the guest should be able to disable crash
actions that userspace has enabled in hv_crash_ctl.

> -       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
> --
> 1.9.1
>
> --
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