[PATCH 3/4] KVM: arm64: Parse reserved-memory node for pkvm guest firmware region

[Will Deacon]

Add support for a "linux,pkvm-guest-firmware-memory" reserved memory
region, which can be used to identify a firmware image for protected
VMs.

Signed-off-by: Will Deacon <will at kernel.org>
---
 arch/arm64/kvm/Makefile |  2 +-
 arch/arm64/kvm/pkvm.c   | 52 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 53 insertions(+), 1 deletion(-)
 create mode 100644 arch/arm64/kvm/pkvm.c

diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile
index 589921392cb1..61e054411831 100644
--- a/arch/arm64/kvm/Makefile
+++ b/arch/arm64/kvm/Makefile
@@ -14,7 +14,7 @@ kvm-y := $(KVM)/kvm_main.o $(KVM)/coalesced_mmio.o $(KVM)/eventfd.o \
 	 $(KVM)/vfio.o $(KVM)/irqchip.o \
 	 arm.o mmu.o mmio.o psci.o perf.o hypercalls.o pvtime.o \
 	 inject_fault.o va_layout.o handle_exit.o \
-	 guest.o debug.o reset.o sys_regs.o \
+	 guest.o debug.o pkvm.o reset.o sys_regs.o \
 	 vgic-sys-reg-v3.o fpsimd.o pmu.o \
 	 arch_timer.o trng.o\
 	 vgic/vgic.o vgic/vgic-init.o \
diff --git a/arch/arm64/kvm/pkvm.c b/arch/arm64/kvm/pkvm.c
new file mode 100644
index 000000000000..7af5d03a3941
--- /dev/null
+++ b/arch/arm64/kvm/pkvm.c
@@ -0,0 +1,52 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * KVM host (EL1) interface to Protected KVM (pkvm) code at EL2.
+ *
+ * Copyright (C) 2021 Google LLC
+ * Author: Will Deacon <will at kernel.org>
+ */
+
+#include <linux/kvm_host.h>
+#include <linux/mm.h>
+#include <linux/of_fdt.h>
+#include <linux/of_reserved_mem.h>
+
+static struct reserved_mem *pkvm_firmware_mem;
+
+static int __init pkvm_firmware_rmem_err(struct reserved_mem *rmem,
+					 const char *reason)
+{
+	phys_addr_t end = rmem->base + rmem->size;
+
+	kvm_err("Ignoring pkvm guest firmware memory reservation [%pa - %pa]: %s\n",
+		&rmem->base, &end, reason);
+	return -EINVAL;
+}
+
+static int __init pkvm_firmware_rmem_init(struct reserved_mem *rmem)
+{
+	unsigned long node = rmem->fdt_node;
+
+	if (kvm_get_mode() != KVM_MODE_PROTECTED)
+		return pkvm_firmware_rmem_err(rmem, "protected mode not enabled");
+
+	if (pkvm_firmware_mem)
+		return pkvm_firmware_rmem_err(rmem, "duplicate reservation");
+
+	if (!of_get_flat_dt_prop(node, "no-map", NULL))
+		return pkvm_firmware_rmem_err(rmem, "missing \"no-map\" property");
+
+	if (of_get_flat_dt_prop(node, "reusable", NULL))
+		return pkvm_firmware_rmem_err(rmem, "\"reusable\" property unsupported");
+
+	if (!PAGE_ALIGNED(rmem->base))
+		return pkvm_firmware_rmem_err(rmem, "base is not page-aligned");
+
+	if (!PAGE_ALIGNED(rmem->size))
+		return pkvm_firmware_rmem_err(rmem, "size is not page-aligned");
+
+	pkvm_firmware_mem = rmem;
+	return 0;
+}
+RESERVEDMEM_OF_DECLARE(pkvm_firmware, "linux,pkvm-guest-firmware-memory",
+		       pkvm_firmware_rmem_init);
-- 
2.32.0.rc0.204.g9fa02ecfa5-goog