Implement the previously defined ioremap/iounmap hooks for arm64, calling into KVM's MMIO guard if available.
Signed-off-by: Marc Zyngier <[email protected]> --- 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 _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
