[PATCH 3/4] KVM: arm64: Move the private VA allocation cursor to __io_map_next

[Fuad Tabba]

__io_map_base is the start of the private VA range only until the first
allocation from it, after which it is the allocation cursor. Keep it as
the start and move the cursor to __io_map_next, for the walk of the
range the next patch adds.

No functional change intended.

Signed-off-by: Fuad Tabba <fuad.tabba at linux.dev>
---
 arch/arm64/kvm/hyp/nvhe/mm.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/arch/arm64/kvm/hyp/nvhe/mm.c b/arch/arm64/kvm/hyp/nvhe/mm.c
index 3b0bee496bffb..422ee57be9560 100644
--- a/arch/arm64/kvm/hyp/nvhe/mm.c
+++ b/arch/arm64/kvm/hyp/nvhe/mm.c
@@ -25,6 +25,7 @@ struct memblock_region hyp_memory[HYP_MEMBLOCK_REGIONS];
 unsigned int hyp_memblock_nr;
 
 static u64 __io_map_base;
+static u64 __io_map_next;
 
 struct hyp_fixmap_slot {
 	u64 addr;
@@ -50,7 +51,7 @@ static int __pkvm_alloc_private_va_range(unsigned long start, size_t size)
 
 	hyp_assert_lock_held(&pkvm_pgd_lock);
 
-	if (!start || start < __io_map_base)
+	if (!start || start < __io_map_next)
 		return -EINVAL;
 
 	/* The allocated size is always a multiple of PAGE_SIZE */
@@ -60,7 +61,7 @@ static int __pkvm_alloc_private_va_range(unsigned long start, size_t size)
 	if (cur > __hyp_vmemmap)
 		return -ENOMEM;
 
-	__io_map_base = cur;
+	__io_map_next = cur;
 
 	return 0;
 }
@@ -70,7 +71,7 @@ static int __pkvm_alloc_private_va_range(unsigned long start, size_t size)
  * @size:	The size of the VA range to reserve.
  * @haddr:	The hypervisor virtual start address of the allocation.
  *
- * The private virtual address (VA) range is allocated above __io_map_base
+ * The private virtual address (VA) range is allocated above __io_map_next
  * and aligned based on the order of @size.
  *
  * Return: 0 on success or negative error code on failure.
@@ -81,7 +82,7 @@ int pkvm_alloc_private_va_range(size_t size, unsigned long *haddr)
 	int ret;
 
 	hyp_spin_lock(&pkvm_pgd_lock);
-	addr = __io_map_base;
+	addr = __io_map_next;
 	ret = __pkvm_alloc_private_va_range(addr, size);
 	hyp_spin_unlock(&pkvm_pgd_lock);
 
@@ -341,7 +342,7 @@ static int create_fixblock(void)
 		return -EINVAL;
 
 	hyp_spin_lock(&pkvm_pgd_lock);
-	addr = ALIGN(__io_map_base, PMD_SIZE);
+	addr = ALIGN(__io_map_next, PMD_SIZE);
 	ret = __pkvm_alloc_private_va_range(addr, PMD_SIZE);
 	if (ret)
 		goto unlock;
@@ -426,6 +427,7 @@ int hyp_create_idmap(u32 hyp_va_bits)
 	 */
 	__io_map_base = start & BIT(hyp_va_bits - 2);
 	__io_map_base ^= BIT(hyp_va_bits - 2);
+	__io_map_next = __io_map_base;
 	__hyp_vmemmap = __io_map_base | BIT(hyp_va_bits - 3);
 
 	return __pkvm_create_mappings(start, end - start, start, PAGE_HYP_EXEC);
@@ -433,19 +435,19 @@ int hyp_create_idmap(u32 hyp_va_bits)
 
 int pkvm_create_stack(phys_addr_t phys, unsigned long *haddr)
 {
-	unsigned long addr, prev_base;
+	unsigned long addr, prev_next;
 	size_t size;
 	int ret;
 
 	hyp_spin_lock(&pkvm_pgd_lock);
 
-	prev_base = __io_map_base;
+	prev_next = __io_map_next;
 	/*
 	 * Efficient stack verification using the NVHE_STACK_SHIFT bit implies
 	 * an alignment of our allocation on the order of the size.
 	 */
 	size = NVHE_STACK_SIZE * 2;
-	addr = ALIGN(__io_map_base, size);
+	addr = ALIGN(__io_map_next, size);
 
 	ret = __pkvm_alloc_private_va_range(addr, size);
 	if (!ret) {
@@ -461,7 +463,7 @@ int pkvm_create_stack(phys_addr_t phys, unsigned long *haddr)
 		ret = kvm_pgtable_hyp_map(&pkvm_pgtable, addr + NVHE_STACK_SIZE,
 					  NVHE_STACK_SIZE, phys, PAGE_HYP);
 		if (ret)
-			__io_map_base = prev_base;
+			__io_map_next = prev_next;
 	}
 	hyp_spin_unlock(&pkvm_pgd_lock);
 
-- 
2.39.5