linux-kernel - [PATCH v2 3/7] KVM: arm64: Use 0b11 for encoding PKVM

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Message-ID: <20250416152648.2982950-4-qperret@google.com>
Date: Wed, 16 Apr 2025 15:26:43 +0000
From: Quentin Perret <qperret@...gle.com>
To: Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>, 
	Joey Gouly <joey.gouly@....com>, Suzuki K Poulose <suzuki.poulose@....com>, 
	Zenghui Yu <yuzenghui@...wei.com>, Catalin Marinas <catalin.marinas@....com>, 
	Will Deacon <will@...nel.org>
Cc: Vincent Donnefort <vdonnefort@...gle.com>, Fuad Tabba <tabba@...gle.com>, 
	Quentin Perret <qperret@...gle.com>, linux-arm-kernel@...ts.infradead.org, 
	kvmarm@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: [PATCH v2 3/7] KVM: arm64: Use 0b11 for encoding PKVM_NOPAGE

The page ownership state encoded as 0b11 is currently considered
reserved for future use, and PKVM_NOPAGE uses bit 2. In order to
simplify the relocation of the hyp ownership state into the
vmemmap in later patches, let's use the 'reserved' encoding for
the PKVM_NOPAGE state. The struct hyp_page layout isn't guaranteed
stable at all, so there is no real reason to have 'reserved' encodings.

No functional changes intended.

Reviewed-by: Marc Zyngier <maz@...nel.org>
Signed-off-by: Quentin Perret <qperret@...gle.com>
---
 arch/arm64/kvm/hyp/include/nvhe/memory.h | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/arch/arm64/kvm/hyp/include/nvhe/memory.h b/arch/arm64/kvm/hyp/include/nvhe/memory.h
index 178028172c0b..bf28f9f9de65 100644
--- a/arch/arm64/kvm/hyp/include/nvhe/memory.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/memory.h
@@ -23,7 +23,6 @@ enum pkvm_page_state {
 	PKVM_PAGE_OWNED			= 0ULL,
 	PKVM_PAGE_SHARED_OWNED		= BIT(0),
 	PKVM_PAGE_SHARED_BORROWED	= BIT(1),
-	__PKVM_PAGE_RESERVED            = BIT(0) | BIT(1),
 
 	/*
 	 * 'Meta-states' are not stored directly in PTE SW bits for hyp and
@@ -31,9 +30,8 @@ enum pkvm_page_state {
 	 * entries). For the host, meta-states are stored directly in the
 	 * struct hyp_page.
 	 */
-	PKVM_NOPAGE			= BIT(2),
+	PKVM_NOPAGE			= BIT(0) | BIT(1),
 };
-#define PKVM_PAGE_META_STATES_MASK	(~__PKVM_PAGE_RESERVED)
 
 #define PKVM_PAGE_STATE_PROT_MASK	(KVM_PGTABLE_PROT_SW0 | KVM_PGTABLE_PROT_SW1)
 static inline enum kvm_pgtable_prot pkvm_mkstate(enum kvm_pgtable_prot prot,
-- 
2.49.0.604.gff1f9ca942-goog