KVM: arm64: Convert translation level parameter to s8

With the introduction of FEAT_LPA2, the Arm ARM adds a new level of
translation, level -1, so levels can now be in the range [-1;3]. 3 is
always the last level and the first level is determined based on the
number of VA bits in use.

Convert level variables to use a signed type in preparation for
supporting this new level -1.

Since the last level is always anchored at 3, and the first level varies
to suit the number of VA/IPA bits, take the opportunity to replace
KVM_PGTABLE_MAX_LEVELS with the 2 macros KVM_PGTABLE_FIRST_LEVEL and
KVM_PGTABLE_LAST_LEVEL. This removes the assumption from the code that
levels run from 0 to KVM_PGTABLE_MAX_LEVELS - 1, which will soon no
longer be true.

Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20231127111737.1897081-9-ryan.roberts@arm.com

1 files changed, 3 insertions, 2 deletions

diff --git a/arch/arm64/include/asm/kvm_pkvm.h b/arch/arm64/include/asm/kvm_pkvm.h
index e46250a02017..ad9cfb5c1ff4 100644
--- a/arch/arm64/include/asm/kvm_pkvm.h
+++ b/arch/arm64/include/asm/kvm_pkvm.h
@@ -56,10 +56,11 @@ static inline unsigned long hyp_vm_table_pages(void)
 
 static inline unsigned long __hyp_pgtable_max_pages(unsigned long nr_pages)
 {
-	unsigned long total = 0, i;
+	unsigned long total = 0;
+	int i;
 
 	/* Provision the worst case scenario */
-	for (i = 0; i < KVM_PGTABLE_MAX_LEVELS; i++) {
+	for (i = KVM_PGTABLE_FIRST_LEVEL; i <= KVM_PGTABLE_LAST_LEVEL; i++) {
 		nr_pages = DIV_ROUND_UP(nr_pages, PTRS_PER_PTE);
 		total += nr_pages;
 	}