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ANDROID: arm64: Implement ioremap/iounmap hooks calling into KVM's MMIO guard

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Implement the previously defined ioremap/iounmap hooks for arm64,
calling into KVM's MMIO guard if available.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Bug: 209580772
Change-Id: I86a78f8941fb60078fb873a34c5eb32830a00259
Signed-off-by: Will Deacon <willdeacon@google.com>
This commit is contained in:
Marc Zyngier
2021-06-30 13:31:56 +01:00
committed by Will Deacon
parent acd8b4b1f1
commit 078e81b0c1
1 changed files with 112 additions and 0 deletions
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112
arch/arm64/mm/ioremap.c
View File

@@ -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)