ANDROID: KVM: arm64: Specify stage-2-protected regions in DT

Parse the devicetree during pKVM init to find nodes with the
"pkvm,protected-region" compatible string. These nodes specify a
physical address range in reg that must alway be mapped as invalid in
the host stage-2 page table when running under pKVM.

Example DT:

        pkvm_prot_reg: pkvm_prot_reg@80000000 {
                compatible = "pkvm,protected-region";
                reg = <0x00 0x80000000 0x00 0x200000>;
        };

Bug: 244543039
Bug: 244373730
Change-Id: I102cd16c91d96e5283cdd1a4fa58836cc4834eac
Signed-off-by: Quentin Perret <qperret@google.com>

arch/arm64/include/asm/kvm_pkvm.h

@@ -244,6 +244,7 @@ static inline int pkvm_get_max_wrps(void)
 
 enum pkvm_moveable_reg_type {
 	PKVM_MREG_MEMORY,
+	PKVM_MREG_PROTECTED_RANGE,
 };
 
 struct pkvm_moveable_reg {

arch/arm64/kvm/hyp/include/nvhe/mem_protect.h

@@ -60,7 +60,8 @@ enum pkvm_component_id {
 	PKVM_ID_HYP,
 	PKVM_ID_GUEST,
 	PKVM_ID_FFA,
-	PKVM_ID_MAX = PKVM_ID_FFA,
+	PKVM_ID_PROTECTED,
+	PKVM_ID_MAX = PKVM_ID_PROTECTED,
 };
 
 extern unsigned long hyp_nr_cpus;
@@ -87,6 +88,7 @@ bool addr_is_memory(phys_addr_t phys);
 int host_stage2_idmap_locked(phys_addr_t addr, u64 size, enum kvm_pgtable_prot prot,
 			     bool update_iommu);
 int host_stage2_set_owner_locked(phys_addr_t addr, u64 size, enum pkvm_component_id owner_id);
+int host_stage2_protect_pages_locked(phys_addr_t addr, u64 size);
 int host_stage2_unmap_reg_locked(phys_addr_t start, u64 size);
 int kvm_host_prepare_stage2(void *pgt_pool_base);
 int kvm_guest_prepare_stage2(struct pkvm_hyp_vm *vm, void *pgd);

arch/arm64/kvm/hyp/nvhe/mem_protect.c

@@ -2235,3 +2235,16 @@ bool __pkvm_check_ioguard_page(struct pkvm_hyp_vcpu *hyp_vcpu)
 
 	return ret;
 }
+
+int host_stage2_protect_pages_locked(phys_addr_t addr, u64 size)
+{
+	int ret;
+
+	hyp_assert_lock_held(&host_mmu.lock);
+
+	ret = __host_check_page_state_range(addr, size, PKVM_PAGE_OWNED);
+	if (!ret)
+		ret = host_stage2_set_owner_locked(addr, size, PKVM_ID_PROTECTED);
+
+	return ret;
+}

arch/arm64/kvm/hyp/nvhe/setup.c

@@ -303,6 +303,23 @@ static int fix_hyp_pgtable_refcnt(void)
 				&walker);
 }
 
+static int unmap_protected_regions(void)
+{
+	struct pkvm_moveable_reg *reg;
+	int i, ret;
+
+	for (i = 0; i < pkvm_moveable_regs_nr; i++) {
+		reg = &pkvm_moveable_regs[i];
+		if (reg->type != PKVM_MREG_PROTECTED_RANGE)
+			continue;
+		ret = host_stage2_protect_pages_locked(reg->start, reg->size);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
 void __noreturn __pkvm_init_finalise(void)
 {
 	struct kvm_host_data *host_data = this_cpu_ptr(&kvm_host_data);
@@ -344,6 +361,10 @@ void __noreturn __pkvm_init_finalise(void)
 	if (ret)
 		goto out;
 
+	ret = unmap_protected_regions();
+	if (ret)
+		goto out;
+
 	ret = hyp_ffa_init(ffa_proxy_pages);
 	if (ret)
 		goto out;

arch/arm64/kvm/pkvm.c

@@ -9,6 +9,7 @@
 #include <linux/memblock.h>
 #include <linux/mm.h>
 #include <linux/mutex.h>
+#include <linux/of_address.h>
 #include <linux/of_fdt.h>
 #include <linux/of_reserved_mem.h>
 #include <linux/sort.h>
@@ -97,6 +98,7 @@ static void __init sort_moveable_regs(void)
 static int __init register_moveable_regions(void)
 {
 	struct memblock_region *reg;
+	struct device_node *np;
 	int i = 0;
 
 	for_each_mem_region(reg) {
@@ -107,6 +109,30 @@ static int __init register_moveable_regions(void)
 		moveable_regs[i].type = PKVM_MREG_MEMORY;
 		i++;
 	}
+
+	for_each_compatible_node(np, NULL, "pkvm,protected-region") {
+		struct resource res;
+		u64 start, size;
+		int ret;
+
+		if (i >= PKVM_NR_MOVEABLE_REGS)
+			return -ENOMEM;
+
+		ret = of_address_to_resource(np, 0, &res);
+		if (ret)
+			return ret;
+
+		start = res.start;
+		size = resource_size(&res);
+		if (!PAGE_ALIGNED(start) || !PAGE_ALIGNED(size))
+			return -EINVAL;
+
+		moveable_regs[i].start = start;
+		moveable_regs[i].size = size;
+		moveable_regs[i].type = PKVM_MREG_PROTECTED_RANGE;
+		i++;
+	}
+
 	kvm_nvhe_sym(pkvm_moveable_regs_nr) = i;
 	sort_moveable_regs();