KVM: arm64: Work out supported block level at compile time

Bugzilla: https://bugzilla.redhat.com/2128973

commit 3b5c082
Author: Oliver Upton <oliver.upton@linux.dev>
Date:   Fri Oct 7 23:41:50 2022 +0000

    KVM: arm64: Work out supported block level at compile time

    Work out the minimum page table level where KVM supports block mappings
    at compile time. While at it, rewrite the comment around supported block
    mappings to directly describe what KVM supports instead of phrasing in
    terms of what it does not.

    Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
    Signed-off-by: Marc Zyngier <maz@kernel.org>
    Link: https://lore.kernel.org/r/20221007234151.461779-2-oliver.upton@linux.dev

Signed-off-by: Cornelia Huck <cohuck@redhat.com>

Author: cohuck

arch/arm64/include/asm/kvm_pgtable.h

@@ -13,6 +13,18 @@
 
 #define KVM_PGTABLE_MAX_LEVELS		4U
 
+/*
+ * The largest supported block sizes for KVM (no 52-bit PA support):
+ *  - 4K (level 1):	1GB
+ *  - 16K (level 2):	32MB
+ *  - 64K (level 2):	512MB
+ */
+#ifdef CONFIG_ARM64_4K_PAGES
+#define KVM_PGTABLE_MIN_BLOCK_LEVEL	1U
+#else
+#define KVM_PGTABLE_MIN_BLOCK_LEVEL	2U
+#endif
+
 static inline u64 kvm_get_parange(u64 mmfr0)
 {
 	u64 parange = cpuid_feature_extract_unsigned_field(mmfr0,
@@ -58,11 +70,7 @@ static inline u64 kvm_granule_size(u32 level)
 
 static inline bool kvm_level_supports_block_mapping(u32 level)
 {
-	/*
-	 * Reject invalid block mappings and don't bother with 4TB mappings for
-	 * 52-bit PAs.
-	 */
-	return !(level == 0 || (PAGE_SIZE != SZ_4K && level == 1));
+	return level >= KVM_PGTABLE_MIN_BLOCK_LEVEL;
 }
 
 /**