linux-kernel - [PATCH] KVM: arm64: Report Protected KVM cap only if KVM is enabled

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Date:   Thu, 1 Sep 2022 21:01:22 -0700
From:   Elliot Berman <quic_eberman@...cinc.com>
To:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, Marc Zyngier <maz@...nel.org>,
        James Morse <james.morse@....com>,
        "Alexandru Elisei" <alexandru.elisei@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>
CC:     Elliot Berman <quic_eberman@...cinc.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <kvmarm@...ts.cs.columbia.edu>,
        David Brazdil <dbrazdil@...gle.com>
Subject: [PATCH] KVM: arm64: Report Protected KVM cap only if KVM is enabled

If "kvm-arm.mode=protected" is present on kernel command line, but the
kernel doesn't actually support KVM because it booted from EL1, the
ARM64_KVM_PROTECTED_MODE capability is misleadingly reported as present.
Fix this by adding a check whether we booted from EL2.

Cc: Will Deacon <will@...nel.org>
Cc: David Brazdil <dbrazdil@...gle.com>
Cc: Marc Zyngier <maz@...nel.org>
Signed-off-by: Elliot Berman <quic_eberman@...cinc.com>
---
 arch/arm64/kernel/cpufeature.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 8d88433de81d..866667be0651 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1974,7 +1974,7 @@ 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)
 {
-	return kvm_get_mode() == KVM_MODE_PROTECTED;
+	return is_hyp_mode_available() && kvm_get_mode() == KVM_MODE_PROTECTED;
 }
 #endif /* CONFIG_KVM */
 

base-commit: 0982c8d859f8f7022b9fd44d421c7ec721bb41f9
-- 
2.25.1