linux-kernel - [PATCH 5.7 284/477] KVM: PPC: Book3S HV: Relax check on H_SVM_INIT

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Date:   Tue, 23 Jun 2020 21:54:41 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Laurent Dufour <ldufour@...ux.ibm.com>,
        Greg Kurz <groug@...d.org>, Ram Pai <linuxram@...ibm.com>,
        Paul Mackerras <paulus@...abs.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.7 284/477] KVM: PPC: Book3S HV: Relax check on H_SVM_INIT_ABORT

From: Laurent Dufour <ldufour@...ux.ibm.com>

[ Upstream commit e3326ae3d59e443a379367c6936941d6ab55d316 ]

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>
Reviewed-by: Greg Kurz <groug@...d.org>
Reviewed-by: Ram Pai <linuxram@...ibm.com>
Signed-off-by: Paul Mackerras <paulus@...abs.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/powerpc/kvm/book3s_hv.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 93493f0cbfe8e..ee581cde48788 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -1099,9 +1099,14 @@ 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.
+		 * Instead the kvm->arch.secure_guest flag is checked inside
+		 * kvmppc_h_svm_init_abort().
+		 */
+		ret = kvmppc_h_svm_init_abort(vcpu->kvm);
 		break;
 
 	default:
-- 
2.25.1