[PATCH v1 1/4] KVM: arm64: Move the IPA limit rule into kvm_get_ipa_max()

[Fuad Tabba <fuad.tabba@linux.dev>]

Move the rule kvm_set_ipa_limit() applies to PARange into a helper
beside kvm_get_parange(), which bounds the same field by a different
rule, so the hypervisor can size a guest's IPA space by it.

No functional change intended.

Signed-off-by: Fuad Tabba <fuad.tabba@linux.dev>
---
 arch/arm64/include/asm/kvm_pgtable.h | 15 +++++++++++++++
 arch/arm64/kvm/reset.c               | 12 +-----------
 2 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
index 41a8687938eb6..8096b0bf381c2 100644
--- a/arch/arm64/include/asm/kvm_pgtable.h
+++ b/arch/arm64/include/asm/kvm_pgtable.h
@@ -48,6 +48,21 @@ static inline u64 kvm_get_parange(u64 mmfr0)
 	return parange;
 }
 
+/*
+ * The largest IPA size a VM can be given. Unlike VTCR_EL2.PS
+ * (kvm_get_parange()), it isn't clamped to the kernel's PA configuration.
+ */
+static inline u32 kvm_get_ipa_max(u64 mmfr0)
+{
+	unsigned int parange = cpuid_feature_extract_unsigned_field(mmfr0,
+				ID_AA64MMFR0_EL1_PARANGE_SHIFT);
+
+	if (!kvm_lpa2_is_enabled() && PAGE_SIZE != SZ_64K)
+		parange = min(parange, (unsigned int)ID_AA64MMFR0_EL1_PARANGE_48);
+
+	return id_aa64mmfr0_parange_to_phys_shift(parange);
+}
+
 typedef u64 kvm_pte_t;
 
 #define KVM_PTE_VALID			BIT(0)
diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index 10eb7249aa9e8..757adbce2faac 100644
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -231,19 +231,9 @@ u32 get_kvm_ipa_limit(void)
 
 int __init kvm_set_ipa_limit(void)
 {
-	unsigned int parange;
 	u64 mmfr0;
 
 	mmfr0 = read_sanitised_ftr_reg(SYS_ID_AA64MMFR0_EL1);
-	parange = cpuid_feature_extract_unsigned_field(mmfr0,
-				ID_AA64MMFR0_EL1_PARANGE_SHIFT);
-	/*
-	 * IPA size beyond 48 bits for 4K and 16K page size is only supported
-	 * when LPA2 is available. So if we have LPA2, enable it, else cap to 48
-	 * bits, in case it's reported as larger on the system.
-	 */
-	if (!kvm_lpa2_is_enabled() && PAGE_SIZE != SZ_64K)
-		parange = min(parange, (unsigned int)ID_AA64MMFR0_EL1_PARANGE_48);
 
 	/*
 	 * Check with ARMv8.5-GTG that our PAGE_SIZE is supported at
@@ -264,7 +254,7 @@ int __init kvm_set_ipa_limit(void)
 		return -EINVAL;
 	}
 
-	kvm_ipa_limit = id_aa64mmfr0_parange_to_phys_shift(parange);
+	kvm_ipa_limit = kvm_get_ipa_max(mmfr0);
 	kvm_info("IPA Size Limit: %d bits%s\n", kvm_ipa_limit,
 		 ((kvm_ipa_limit < KVM_PHYS_SHIFT) ?
 		  " (Reduced IPA size, limited VM/VMM compatibility)" : ""));
-- 
2.39.5