The commit 8c47b6ff29e3 ("KVM: PPC: Book3S HV: Check caller of H_SVM_*
Hcalls") added checks of secure bit of SRR1 to filter out the Hcall
reserved to the Ultravisor.
However, the Hcall H_SVM_INIT_ABORT is made by the Ultravisor passing the
context of the VM calling UV_ESM. This allows the Hypervisor to return to
the guest without going through the Ultravisor. Thus the Secure bit of SRR1
is not set in that particular case.
In the case a regular VM is calling H_SVM_INIT_ABORT, this hcall will be
filtered out in kvmppc_h_svm_init_abort() because kvm->arch.secure_guest is
not set in that case.
Fixes: 8c47b6ff29e3 ("KVM: PPC: Book3S HV: Check caller of H_SVM_* Hcalls")
Signed-off-by: Laurent Dufour <[email protected]>
---
arch/powerpc/kvm/book3s_hv.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 93493f0cbfe8..eb1f96cb7b72 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -1099,9 +1099,7 @@ int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu)
ret = kvmppc_h_svm_init_done(vcpu->kvm);
break;
case H_SVM_INIT_ABORT:
- ret = H_UNSUPPORTED;
- if (kvmppc_get_srr1(vcpu) & MSR_S)
- ret = kvmppc_h_svm_init_abort(vcpu->kvm);
+ ret = kvmppc_h_svm_init_abort(vcpu->kvm);
break;
default:
--
2.26.2
Le 20/05/2020 à 19:32, Greg Kurz a écrit :
> On Wed, 20 May 2020 18:51:10 +0200
> Laurent Dufour <[email protected]> wrote:
>
>> The commit 8c47b6ff29e3 ("KVM: PPC: Book3S HV: Check caller of H_SVM_*
>> Hcalls") added checks of secure bit of SRR1 to filter out the Hcall
>> reserved to the Ultravisor.
>>
>> However, the Hcall H_SVM_INIT_ABORT is made by the Ultravisor passing the
>> context of the VM calling UV_ESM. This allows the Hypervisor to return to
>> the guest without going through the Ultravisor. Thus the Secure bit of SRR1
>> is not set in that particular case.
>>
>> In the case a regular VM is calling H_SVM_INIT_ABORT, this hcall will be
>> filtered out in kvmppc_h_svm_init_abort() because kvm->arch.secure_guest is
>> not set in that case.
>>
>
> Why not checking vcpu->kvm->arch.secure_guest then ?
I don't think that's the right place.
>
>> Fixes: 8c47b6ff29e3 ("KVM: PPC: Book3S HV: Check caller of H_SVM_* Hcalls")
>> Signed-off-by: Laurent Dufour <[email protected]>
>> ---
>> arch/powerpc/kvm/book3s_hv.c | 4 +---
>> 1 file changed, 1 insertion(+), 3 deletions(-)
>>
>> diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
>> index 93493f0cbfe8..eb1f96cb7b72 100644
>> --- a/arch/powerpc/kvm/book3s_hv.c
>> +++ b/arch/powerpc/kvm/book3s_hv.c
>> @@ -1099,9 +1099,7 @@ int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu)
>> ret = kvmppc_h_svm_init_done(vcpu->kvm);
>> break;
>> case H_SVM_INIT_ABORT:
>> - ret = H_UNSUPPORTED;
>> - if (kvmppc_get_srr1(vcpu) & MSR_S)
>> - ret = kvmppc_h_svm_init_abort(vcpu->kvm);
>
> or at least put a comment to explain why H_SVM_INIT_ABORT
> doesn't have the same sanity check as the other SVM hcalls.
I agree that might help. I'll send a v2 with a comment there.
>
>> + ret = kvmppc_h_svm_init_abort(vcpu->kvm);
>> break;
>>
>> default:
>
On Wed, 20 May 2020 18:51:10 +0200
Laurent Dufour <[email protected]> wrote:
> The commit 8c47b6ff29e3 ("KVM: PPC: Book3S HV: Check caller of H_SVM_*
> Hcalls") added checks of secure bit of SRR1 to filter out the Hcall
> reserved to the Ultravisor.
>
> However, the Hcall H_SVM_INIT_ABORT is made by the Ultravisor passing the
> context of the VM calling UV_ESM. This allows the Hypervisor to return to
> the guest without going through the Ultravisor. Thus the Secure bit of SRR1
> is not set in that particular case.
>
> In the case a regular VM is calling H_SVM_INIT_ABORT, this hcall will be
> filtered out in kvmppc_h_svm_init_abort() because kvm->arch.secure_guest is
> not set in that case.
>
Why not checking vcpu->kvm->arch.secure_guest then ?
> Fixes: 8c47b6ff29e3 ("KVM: PPC: Book3S HV: Check caller of H_SVM_* Hcalls")
> Signed-off-by: Laurent Dufour <[email protected]>
> ---
> arch/powerpc/kvm/book3s_hv.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
> index 93493f0cbfe8..eb1f96cb7b72 100644
> --- a/arch/powerpc/kvm/book3s_hv.c
> +++ b/arch/powerpc/kvm/book3s_hv.c
> @@ -1099,9 +1099,7 @@ int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu)
> ret = kvmppc_h_svm_init_done(vcpu->kvm);
> break;
> case H_SVM_INIT_ABORT:
> - ret = H_UNSUPPORTED;
> - if (kvmppc_get_srr1(vcpu) & MSR_S)
> - ret = kvmppc_h_svm_init_abort(vcpu->kvm);
or at least put a comment to explain why H_SVM_INIT_ABORT
doesn't have the same sanity check as the other SVM hcalls.
> + ret = kvmppc_h_svm_init_abort(vcpu->kvm);
> break;
>
> default: