Implement the previously defined ioremap/iounmap hooks for arm64,
calling into KVM's MMIO guard if available.
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
---
arch/arm64/mm/ioremap.c | 112 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 112 insertions(+)
diff --git a/arch/arm64/mm/ioremap.c b/arch/arm64/mm/ioremap.c
index b7c81dacabf0..5334cbdc9f64 100644
--- a/arch/arm64/mm/ioremap.c
+++ b/arch/arm64/mm/ioremap.c
@@ -9,13 +9,125 @@
* Copyright (C) 2012 ARM Ltd.
*/
+#define pr_fmt(fmt) "ioremap: " fmt
+
#include <linux/export.h>
#include <linux/mm.h>
#include <linux/vmalloc.h>
+#include <linux/slab.h>
#include <linux/io.h>
+#include <linux/arm-smccc.h>
#include <asm/fixmap.h>
#include <asm/tlbflush.h>
+#include <asm/hypervisor.h>
+
+struct ioremap_guard_ref {
+ refcount_t count;
+};
+
+static DEFINE_STATIC_KEY_FALSE(ioremap_guard_key);
+static DEFINE_XARRAY(ioremap_guard_array);
+static DEFINE_MUTEX(ioremap_guard_lock);
+
+void ioremap_phys_range_hook(phys_addr_t phys_addr, size_t size, pgprot_t prot)
+{
+ if (!static_branch_unlikely(&ioremap_guard_key))
+ return;
+
+ if (pfn_valid(__phys_to_pfn(phys_addr)))
+ return;
+
+ mutex_lock(&ioremap_guard_lock);
+
+ while (size) {
+ u64 pfn = phys_addr >> PAGE_SHIFT;
+ struct ioremap_guard_ref *ref;
+ struct arm_smccc_res res;
+
+ ref = xa_load(&ioremap_guard_array, pfn);
+ if (ref) {
+ refcount_inc(&ref->count);
+ goto next;
+ }
+
+ /*
+ * It is acceptable for the allocation to fail, specially
+ * if trying to ioremap something very early on, like with
+ * earlycon, which happens long before kmem_cache_init.
+ * This page will be permanently accessible, similar to a
+ * saturated refcount.
+ */
+ ref = kzalloc(sizeof(*ref), GFP_KERNEL);
+ if (ref) {
+ refcount_set(&ref->count, 1);
+ if (xa_err(xa_store(&ioremap_guard_array, pfn, ref,
+ GFP_KERNEL))) {
+ kfree(ref);
+ ref = NULL;
+ }
+ }
+
+ arm_smccc_1_1_hvc(ARM_SMCCC_VENDOR_HYP_KVM_MMIO_GUARD_MAP_FUNC_ID,
+ phys_addr, prot, &res);
+ if (res.a0 != SMCCC_RET_SUCCESS) {
+ pr_warn_ratelimited("Failed to register %llx\n",
+ phys_addr);
+ xa_erase(&ioremap_guard_array, pfn);
+ kfree(ref);
+ goto out;
+ }
+
+ next:
+ size -= PAGE_SIZE;
+ phys_addr += PAGE_SIZE;
+ }
+out:
+ mutex_unlock(&ioremap_guard_lock);
+}
+
+void iounmap_phys_range_hook(phys_addr_t phys_addr, size_t size)
+{
+ if (!static_branch_unlikely(&ioremap_guard_key))
+ return;
+
+ VM_BUG_ON(phys_addr & ~PAGE_MASK || size & ~PAGE_MASK);
+
+ mutex_lock(&ioremap_guard_lock);
+
+ while (size) {
+ u64 pfn = phys_addr >> PAGE_SHIFT;
+ struct ioremap_guard_ref *ref;
+ struct arm_smccc_res res;
+
+ ref = xa_load(&ioremap_guard_array, pfn);
+ if (!ref) {
+ pr_warn_ratelimited("%llx not tracked, left mapped\n",
+ phys_addr);
+ goto next;
+ }
+
+ if (!refcount_dec_and_test(&ref->count))
+ goto next;
+
+ xa_erase(&ioremap_guard_array, pfn);
+ kfree(ref);
+
+ arm_smccc_1_1_hvc(ARM_SMCCC_VENDOR_HYP_KVM_MMIO_GUARD_UNMAP_FUNC_ID,
+ phys_addr, &res);
+ if (res.a0 != SMCCC_RET_SUCCESS) {
+ pr_warn_ratelimited("Failed to unregister %llx\n",
+ phys_addr);
+ goto out;
+ }
+
+ next:
+ size -= PAGE_SIZE;
+ phys_addr += PAGE_SIZE;
+ }
+out:
+ mutex_unlock(&ioremap_guard_lock);
+}
static void __iomem *__ioremap_caller(phys_addr_t phys_addr, size_t size,
pgprot_t prot, void *caller)
--
2.30.2
