Re: [Qemu-devel] [PATCH 7/9] kvm/x86: added hyper-v crash data and ctl msr's get/set'ers

[Peter Hornyack]

On Tue, Jun 30, 2015 at 4:33 AM, Denis V. Lunev <address@hidden> wrote:
> From: Andrey Smetanin <address@hidden>
>
> Added hyper-v crash msr's(HV_X64_MSR_CRASH*) data and control
> geters and setters.
>
> User space allowed to setup Hyper-V crash ctl msr.
> This msr should be setup to HV_X64_MSR_CRASH_CTL_NOTIFY
> value so Hyper-V guest knows it can send crash data to host.
> But Hyper-V guest notifies about crash event by writing
> the same HV_X64_MSR_CRASH_CTL_NOTIFY value into crash ctl msr.
> So 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. Also patch
> prevents modification of crash ctl msr by guest.
>
> 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>
Reviewed-by: Peter Hornyack <address@hidden>

> ---
>  arch/x86/kvm/hyperv.c | 74 
> ++++++++++++++++++++++++++++++++++++++++++++++++---
>  arch/x86/kvm/hyperv.h |  2 +-
>  arch/x86/kvm/x86.c    |  7 ++++-
>  3 files changed, 78 insertions(+), 5 deletions(-)
>
> diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
> index af83c96..a860165 100644
> --- a/arch/x86/kvm/hyperv.c
> +++ b/arch/x86/kvm/hyperv.c
> @@ -48,7 +48,63 @@ static bool kvm_hv_msr_partition_wide(u32 msr)
>         return r;
>  }
>
> -static int kvm_hv_set_msr_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data)
> +static int kvm_hv_msr_get_crash_data(struct kvm_vcpu *vcpu,
> +                                    u32 index, u64 *pdata)
> +{
> +       struct kvm_hv *hv = &vcpu->kvm->arch.hyperv;
> +
> +       if (WARN_ON_ONCE(index >= ARRAY_SIZE(hv->hv_crash_param)))
> +               return -EINVAL;
> +
> +       *pdata = hv->hv_crash_param[index];
> +       return 0;
> +}
> +
> +static int kvm_hv_msr_get_crash_ctl(struct kvm_vcpu *vcpu, u64 *pdata)
> +{
> +       struct kvm_hv *hv = &vcpu->kvm->arch.hyperv;
> +
> +       *pdata = hv->hv_crash_ctl;
> +       return 0;
> +}
> +
> +static int kvm_hv_msr_set_crash_ctl(struct kvm_vcpu *vcpu, u64 data, bool 
> host)
> +{
> +       struct kvm_hv *hv = &vcpu->kvm->arch.hyperv;
> +
> +       if (host)
> +               hv->hv_crash_ctl = data;
> +
> +       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],
> +                         hv->hv_crash_param[2],
> +                         hv->hv_crash_param[3],
> +                         hv->hv_crash_param[4]);
> +
> +               /* Send notification about crash to user space */
> +               kvm_make_request(KVM_REQ_HV_CRASH, vcpu);
> +       }
> +
> +       return 0;
> +}
> +
> +static int kvm_hv_msr_set_crash_data(struct kvm_vcpu *vcpu,
> +                                    u32 index, u64 data)
> +{
> +       struct kvm_hv *hv = &vcpu->kvm->arch.hyperv;
> +
> +       if (WARN_ON_ONCE(index >= ARRAY_SIZE(hv->hv_crash_param)))
> +               return -EINVAL;
> +
> +       hv->hv_crash_param[index] = data;
> +       return 0;
> +}
> +
> +static int kvm_hv_set_msr_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data,
> +                            bool host)
>  {
>         struct kvm *kvm = vcpu->kvm;
>         struct kvm_hv *hv = &kvm->arch.hyperv;
> @@ -101,6 +157,12 @@ static int kvm_hv_set_msr_pw(struct kvm_vcpu *vcpu, u32 
> msr, u64 data)
>                 mark_page_dirty(kvm, gfn);
>                 break;
>         }
> +       case HV_X64_MSR_CRASH_P0 ... HV_X64_MSR_CRASH_P4:
> +               return kvm_hv_msr_set_crash_data(vcpu,
> +                                                msr - HV_X64_MSR_CRASH_P0,
> +                                                data);
> +       case HV_X64_MSR_CRASH_CTL:
> +               return kvm_hv_msr_set_crash_ctl(vcpu, data, host);
>         default:
>                 vcpu_unimpl(vcpu, "Hyper-V uhandled wrmsr: 0x%x data 
> 0x%llx\n",
>                             msr, data);
> @@ -173,6 +235,12 @@ static int kvm_hv_get_msr_pw(struct kvm_vcpu *vcpu, u32 
> msr, u64 *pdata)
>         case HV_X64_MSR_REFERENCE_TSC:
>                 data = hv->hv_tsc_page;
>                 break;
> +       case HV_X64_MSR_CRASH_P0 ... HV_X64_MSR_CRASH_P4:
> +               return kvm_hv_msr_get_crash_data(vcpu,
> +                                                msr - HV_X64_MSR_CRASH_P0,
> +                                                pdata);
> +       case HV_X64_MSR_CRASH_CTL:
> +               return kvm_hv_msr_get_crash_ctl(vcpu, pdata);
>         default:
>                 vcpu_unimpl(vcpu, "Hyper-V unhandled rdmsr: 0x%x\n", msr);
>                 return 1;
> @@ -217,13 +285,13 @@ 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
> diff --git a/arch/x86/kvm/hyperv.h b/arch/x86/kvm/hyperv.h
> index 115c738..c7bce55 100644
> --- a/arch/x86/kvm/hyperv.h
> +++ b/arch/x86/kvm/hyperv.h
> @@ -24,7 +24,7 @@
>  #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);
>  int kvm_hv_hypercall(struct kvm_vcpu *vcpu);
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 301ee01..47b7507 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -2103,7 +2103,10 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct 
> msr_data *msr_info)
>                  */
>                 break;
>         case HV_X64_MSR_GUEST_OS_ID ... HV_X64_MSR_SINT15:
> -               return kvm_hv_set_msr_common(vcpu, msr, data);
> +       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,
> +                                            msr_info->host_initiated);
>         case MSR_IA32_BBL_CR_CTL3:
>                 /* Drop writes to this legacy MSR -- see rdmsr
>                  * counterpart for further detail.
> @@ -2304,6 +2307,8 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct 
> msr_data *msr_info)
>                 msr_info->data = 0x20000000;
>                 break;
>         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_get_msr_common(vcpu,
>                                              msr_info->index, 
> &msr_info->data);
>                 break;
> --
> 2.1.4
>
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