[PATCH 2/4] KVM: arm64: Allow implementations to be confined to using VHE

From: Marc Zyngier <marc.zyngier@arm.com>
To: linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org
Cc: Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>
Subject: [PATCH 2/4] KVM: arm64: Allow implementations to be confined to using VHE
Date: Mon,  5 Nov 2018 14:36:14 +0000	[thread overview]
Message-ID: <20181105143617.120602-3-marc.zyngier@arm.com> (raw)
In-Reply-To: <20181105143617.120602-1-marc.zyngier@arm.com>

Some implementations may be forced to use VHE to work around HW
errata, for example. Let's introduce a helper that checks for
these cases.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
 arch/arm/include/asm/kvm_host.h   | 1 +
 arch/arm64/include/asm/kvm_host.h | 6 ++++++
 virt/kvm/arm/arm.c                | 5 +++++
 3 files changed, 12 insertions(+)

diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
index c3469729f40c..0f2f782548cb 100644
--- a/arch/arm/include/asm/kvm_host.h
+++ b/arch/arm/include/asm/kvm_host.h
@@ -286,6 +286,7 @@ void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot);
 struct kvm_vcpu *kvm_mpidr_to_vcpu(struct kvm *kvm, unsigned long mpidr);
 
 static inline bool kvm_arch_sve_requires_vhe(void) { return false; }
+static inline bool kvm_arch_impl_requires_vhe(void) { return false; }
 static inline void kvm_arch_hardware_unsetup(void) {}
 static inline void kvm_arch_sync_events(struct kvm *kvm) {}
 static inline void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) {}
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index ca1714148400..7d6e974d024a 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -432,6 +432,12 @@ static inline bool kvm_arch_sve_requires_vhe(void)
 	return system_supports_sve();
 }
 
+static inline bool kvm_arch_impl_requires_vhe(void)
+{
+	/* Some implementations have defects that confine them to VHE */
+	return false;
+}
+
 static inline void kvm_arch_hardware_unsetup(void) {}
 static inline void kvm_arch_sync_events(struct kvm *kvm) {}
 static inline void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) {}
diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
index 66de2efddfca..bc90a1cdd27f 100644
--- a/virt/kvm/arm/arm.c
+++ b/virt/kvm/arm/arm.c
@@ -1647,6 +1647,11 @@ int kvm_arch_init(void *opaque)
 			kvm_pr_unimpl("SVE system without VHE unsupported.  Broken cpu?");
 			return -ENODEV;
 		}
+
+		if (kvm_arch_impl_requires_vhe()) {
+			kvm_pr_unimpl("CPU requiring VHE in non-VHE mode");
+			return -ENODEV;
+		}
 	}
 
 	for_each_online_cpu(cpu) {
-- 
2.19.1
