[PATCH v4 23/38] KVM: arm64: Change 'pkvm_handle_t' to u16

[Will Deacon <will@kernel.org>]

'pkvm_handle_t' doesn't need to be a 32-bit type and subsequent patches
will rely on it being no more than 16 bits so that it can be encoded
into a pte annotation.

Change 'pkvm_handle_t' to a u16 and add a compile-type check that the
maximum handle fits into the reduced type.

Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Tested-by: Mostafa Saleh <smostafa@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
---
 arch/arm64/include/asm/kvm_host.h | 2 +-
 arch/arm64/kvm/hyp/nvhe/pkvm.c    | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 31b9454bb74d..0c5e7ce5f187 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -247,7 +247,7 @@ struct kvm_smccc_features {
 	unsigned long vendor_hyp_bmap_2; /* Function numbers 64-127 */
 };
 
-typedef unsigned int pkvm_handle_t;
+typedef u16 pkvm_handle_t;
 
 struct kvm_protected_vm {
 	pkvm_handle_t handle;
diff --git a/arch/arm64/kvm/hyp/nvhe/pkvm.c b/arch/arm64/kvm/hyp/nvhe/pkvm.c
index a2d45f4b0cf6..a7253a884163 100644
--- a/arch/arm64/kvm/hyp/nvhe/pkvm.c
+++ b/arch/arm64/kvm/hyp/nvhe/pkvm.c
@@ -222,6 +222,7 @@ static struct pkvm_hyp_vm **vm_table;
 
 void pkvm_hyp_vm_table_init(void *tbl)
 {
+	BUILD_BUG_ON((u64)HANDLE_OFFSET + KVM_MAX_PVMS > (pkvm_handle_t)-1);
 	WARN_ON(vm_table);
 	vm_table = tbl;
 }
-- 
2.53.0.1018.g2bb0e51243-goog