[PATCH 1/4] KVM: arm64: Ignore 'kvm-arm.mode=protected' when using VHE

From: Will Deacon <will@kernel.org>
To: kvmarm@lists.cs.columbia.edu
Cc: Will Deacon <will@kernel.org>, Marc Zyngier <maz@kernel.org>,
	James Morse <james.morse@arm.com>,
	Alexandru Elisei <alexandru.elisei@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Christoffer Dall <christoffer.dall@arm.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Fuad Tabba <tabba@google.com>,
	Quentin Perret <qperret@google.com>,
	Sean Christopherson <seanjc@google.com>,
	David Brazdil <dbrazdil@google.com>,
	kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/4] KVM: arm64: Ignore 'kvm-arm.mode=protected' when using VHE
Date: Thu,  3 Jun 2021 19:33:44 +0100	[thread overview]
Message-ID: <20210603183347.1695-2-will@kernel.org> (raw)
In-Reply-To: <20210603183347.1695-1-will@kernel.org>

Ignore 'kvm-arm.mode=protected' when using VHE so that kvm_get_mode()
only returns KVM_MODE_PROTECTED on systems where the feature is available.

Cc: David Brazdil <dbrazdil@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
---
 Documentation/admin-guide/kernel-parameters.txt |  1 -
 arch/arm64/kernel/cpufeature.c                  | 10 +---------
 arch/arm64/kvm/arm.c                            |  6 +++++-
 3 files changed, 6 insertions(+), 11 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index cb89dbdedc46..e85dbdf1ee8e 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2300,7 +2300,6 @@
 
 			protected: nVHE-based mode with support for guests whose
 				   state is kept private from the host.
-				   Not valid if the kernel is running in EL2.
 
 			Defaults to VHE/nVHE based on hardware support.
 
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index efed2830d141..dc1f2e747828 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1773,15 +1773,7 @@ static void cpu_enable_mte(struct arm64_cpu_capabilities const *cap)
 #ifdef CONFIG_KVM
 static bool is_kvm_protected_mode(const struct arm64_cpu_capabilities *entry, int __unused)
 {
-	if (kvm_get_mode() != KVM_MODE_PROTECTED)
-		return false;
-
-	if (is_kernel_in_hyp_mode()) {
-		pr_warn("Protected KVM not available with VHE\n");
-		return false;
-	}
-
-	return true;
+	return kvm_get_mode() == KVM_MODE_PROTECTED;
 }
 #endif /* CONFIG_KVM */
 
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 1cb39c0803a4..8d5e23198dfd 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -2121,7 +2121,11 @@ static int __init early_kvm_mode_cfg(char *arg)
 		return -EINVAL;
 
 	if (strcmp(arg, "protected") == 0) {
-		kvm_mode = KVM_MODE_PROTECTED;
+		if (!is_kernel_in_hyp_mode())
+			kvm_mode = KVM_MODE_PROTECTED;
+		else
+			pr_warn_once("Protected KVM not available with VHE\n");
+
 		return 0;
 	}
 
-- 
2.32.0.rc0.204.g9fa02ecfa5-goog

