linux-kernel - [PATCH v2] KVM: PPC: Book3S HV: relax check on H_SVM_INIT

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Message-Id: <20200520174308.77820-1-ldufour@linux.ibm.com>
Date:   Wed, 20 May 2020 19:43:08 +0200
From:   Laurent Dufour <ldufour@...ux.ibm.com>
To:     kvm-ppc@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-kernel@...r.kernel.org, paulus@...ba.org
Cc:     groug@...d.org, mpe@...erman.id.au, sukadev@...ux.ibm.com,
        linuxram@...ibm.com
Subject: [PATCH v2] KVM: PPC: Book3S HV: relax check on H_SVM_INIT_ABORT

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 <ldufour@...ux.ibm.com>
---
 arch/powerpc/kvm/book3s_hv.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 93493f0cbfe8..6ad1a3b14300 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -1099,9 +1099,12 @@ 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);
+		/*
+		 * Even if that call is made by the Ultravisor, the SSR1 value
+		 * is the guest context one, with the secure bit clear as it has
+		 * not yet been secured. So we can't check it here.
+		 */
+		ret = kvmppc_h_svm_init_abort(vcpu->kvm);
 		break;
 
 	default:
-- 
2.26.2