linux-kernel - [PATCH 1/3] KVM: arm64: Check if 52-bits PA is enabled

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Message-Id: <20201025002739.5804-2-gshan@redhat.com>
Date:   Sun, 25 Oct 2020 11:27:37 +1100
From:   Gavin Shan <gshan@...hat.com>
To:     kvmarm@...ts.cs.columbia.edu
Cc:     linux-kernel@...r.kernel.org, will@...nel.org,
        alexandru.elisei@....com, maz@...nel.org
Subject: [PATCH 1/3] KVM: arm64: Check if 52-bits PA is enabled

The 52-bits physical address is disabled until CONFIG_ARM64_PA_BITS_52
is chosen. This uses option for that check, to avoid the unconditional
check on PAGE_SHIFT in the hot path and thus save some CPU cycles.

Signed-off-by: Gavin Shan <gshan@...hat.com>
---
 arch/arm64/kvm/hyp/pgtable.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index 0cdf6e461cbd..fd850353ee89 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -132,8 +132,9 @@ static u64 kvm_pte_to_phys(kvm_pte_t pte)
 {
 	u64 pa = pte & KVM_PTE_ADDR_MASK;
 
-	if (PAGE_SHIFT == 16)
-		pa |= FIELD_GET(KVM_PTE_ADDR_51_48, pte) << 48;
+#ifdef CONFIG_ARM64_PA_BITS_52
+	pa |= FIELD_GET(KVM_PTE_ADDR_51_48, pte) << 48;
+#endif
 
 	return pa;
 }
@@ -142,8 +143,9 @@ static kvm_pte_t kvm_phys_to_pte(u64 pa)
 {
 	kvm_pte_t pte = pa & KVM_PTE_ADDR_MASK;
 
-	if (PAGE_SHIFT == 16)
-		pte |= FIELD_PREP(KVM_PTE_ADDR_51_48, pa >> 48);
+#ifdef CONFIG_ARM64_PA_BITS_52
+	pte |= FIELD_PREP(KVM_PTE_ADDR_51_48, pa >> 48);
+#endif
 
 	return pte;
 }
-- 
2.23.0