linux-kernel - [PATCH 05/14] KVM: arm64: Don't overwrite ignored bits with owner id

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Message-Id: <20210719104735.3681732-6-qperret@google.com>
Date:   Mon, 19 Jul 2021 11:47:26 +0100
From:   Quentin Perret <qperret@...gle.com>
To:     maz@...nel.org, james.morse@....com, alexandru.elisei@....com,
        suzuki.poulose@....com, catalin.marinas@....com, will@...nel.org
Cc:     linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        linux-kernel@...r.kernel.org, ardb@...nel.org, qwandor@...gle.com,
        tabba@...gle.com, dbrazdil@...gle.com, kernel-team@...roid.com,
        Quentin Perret <qperret@...gle.com>
Subject: [PATCH 05/14] KVM: arm64: Don't overwrite ignored bits with owner id

The nVHE protected mode uses invalid mappings in the host stage-2
page-table to track the owner of each page in the system. In order to
allow the usage of ignored bits (a.k.a. software bits) in these
mappings, move the owner encoding away from the top bits.

Signed-off-by: Quentin Perret <qperret@...gle.com>
---
 arch/arm64/kvm/hyp/pgtable.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index a60653cbd8e5..a0ac8c2bc174 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -50,7 +50,7 @@
 					 KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W | \
 					 KVM_PTE_LEAF_ATTR_HI_S2_XN)
 
-#define KVM_INVALID_PTE_OWNER_MASK	GENMASK(63, 56)
+#define KVM_INVALID_PTE_OWNER_MASK	GENMASK(9, 2)
 #define KVM_MAX_OWNER_ID		1
 
 struct kvm_pgtable_walk_data {
-- 
2.32.0.402.g57bb445576-goog