arm64: Allow random seed to be specified for KASLR

Fully fledged bootloaders should really be populating this from within
the guest using virtio-rng, but having a way to specify it on the cmdline
is useful for developers or users without a bootloader.
Signed-off-by: Will Deacon <will.deacon@arm.com>

arm/aarch64/include/kvm/kvm-config-arch.h

@@ -5,7 +5,10 @@
 	OPT_BOOLEAN('\0', "aarch32", &(cfg)->aarch32_guest,		\
 			"Run AArch32 guest"),				\
 	OPT_BOOLEAN('\0', "pmu", &(cfg)->has_pmuv3,			\
-			"Create PMUv3 device"),
+			"Create PMUv3 device"),				\
+	OPT_U64('\0', "kaslr-seed", &(cfg)->kaslr_seed,			\
+			"Specify random seed for Kernel Address Space "	\
+			"Layout Randomization (KASLR)"),
 
 #include "arm-common/kvm-config-arch.h"
 

arm/fdt.c

@@ -142,6 +142,7 @@ static int setup_fdt(struct kvm *kvm)
 	_FDT(fdt_begin_node(fdt, "chosen"));
 	_FDT(fdt_property_cell(fdt, "linux,pci-probe-only", 1));
 	_FDT(fdt_property_string(fdt, "bootargs", kvm->cfg.real_cmdline));
+	_FDT(fdt_property_u64(fdt, "kaslr-seed", kvm->cfg.arch.kaslr_seed));
 
 	/* Initrd */
 	if (kvm->arch.initrd_size != 0) {

arm/include/arm-common/kvm-config-arch.h

@@ -9,6 +9,7 @@ struct kvm_config_arch {
 	bool		virtio_trans_pci;
 	bool		aarch32_guest;
 	bool		has_pmuv3;
+	u64		kaslr_seed;
 	enum irqchip_type irqchip;
 };