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From:   David Brazdil <dbrazdil@google.com>
To:     Marc Zyngier <maz@kernel.org>, Will Deacon <will@kernel.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        James Morse <james.morse@arm.com>,
        Julien Thierry <julien.thierry.kdev@gmail.com>,
        Suzuki K Poulose <suzuki.poulose@arm.com>
Cc:     kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org, android-kvm@google.com,
        kernel-team@android.com, David Brazdil <dbrazdil@google.com>
Subject: [PATCH 1/2] KVM: arm64: Make nVHE ASLR conditional on RANDOMIZE_BASE
Date:   Tue, 21 Jul 2020 10:44:44 +0100
Message-Id: <20200721094445.82184-2-dbrazdil@google.com>
In-Reply-To: <20200721094445.82184-1-dbrazdil@google.com>
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If there are spare bits in non-VHE hyp VA, KVM unconditionally replaces them
with a random tag chosen at init. Disable this if the kernel is built without
RANDOMIZE_BASE to align with kernel behavior.

Signed-off-by: David Brazdil <dbrazdil@google.com>
---
 arch/arm64/kvm/va_layout.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/va_layout.c b/arch/arm64/kvm/va_layout.c
index a4f48c1ac28c..e0404bcab019 100644
--- a/arch/arm64/kvm/va_layout.c
+++ b/arch/arm64/kvm/va_layout.c
@@ -48,7 +48,7 @@ __init void kvm_compute_layout(void)
 	va_mask = GENMASK_ULL(tag_lsb - 1, 0);
 	tag_val = hyp_va_msb;
 
-	if (tag_lsb != (vabits_actual - 1)) {
+	if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && tag_lsb != (vabits_actual - 1)) {
 		/* We have some free bits to insert a random tag. */
 		tag_val |= get_random_long() & GENMASK_ULL(vabits_actual - 2, tag_lsb);
 	}
-- 
2.27.0