[RFC PATCH 31/34] gunyah: allow userspace to set boot cpu context

[Karim Manaouil <karim.manaouil@xxxxxxxxxx>]

Allow userspace hypervisor (e.g. Qemu) to set the context of the boot
cpu. At the moment, only the program counter (PC) is needed.

Signed-off-by: Karim Manaouil <karim.manaouil@xxxxxxxxxx>
---
 arch/arm64/kvm/gunyah.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/arch/arm64/kvm/gunyah.c b/arch/arm64/kvm/gunyah.c
index e8037d636e8f..df922be2429e 100644
--- a/arch/arm64/kvm/gunyah.c
+++ b/arch/arm64/kvm/gunyah.c
@@ -1703,6 +1703,24 @@ static int gunyah_vm_rm_notification(struct notifier_block *nb,
 	}
 }
 
+/*
+ * We only need to set PC to start of kernel
+ */
+static int gunyah_vm_set_boot_ctx(struct gunyah_vm *ghvm)
+{
+	struct kvm_vcpu *vcpu = kvm_get_vcpu(&ghvm->kvm, 0);
+	u64 core_reg = KVM_REG_ARM64 | KVM_REG_SIZE_U64 | KVM_REG_ARM_CORE;
+	struct kvm_one_reg reg;
+	u64 *regaddr;
+
+	reg.id = core_reg | KVM_REG_ARM_CORE_REG(regs.pc);
+	regaddr = core_reg_addr(vcpu, &reg);
+
+	/* We only need to set PC atm. regset is 1 */
+	return gunyah_rm_vm_set_boot_context(
+			ghvm->rm, ghvm->vmid, 1, 0, *regaddr);
+}
+
 static void gunyah_vm_stop(struct gunyah_vm *ghvm)
 {
 	int ret;
@@ -1790,6 +1808,12 @@ static int gunyah_vm_start(struct gunyah_vm *ghvm)
 	}
 	ghvm->vm_status = GUNYAH_RM_VM_STATUS_READY;
 
+	ret = gunyah_vm_set_boot_ctx(ghvm);
+	if (ret) {
+		pr_warn("Failed to setup boot context: %d\n", ret);
+		goto err;
+	}
+
 	ret = gunyah_rm_get_hyp_resources(ghvm->rm, ghvm->vmid, &resources);
 	if (ret) {
 		pr_warn("Failed to get hyp resources for VM: %d\n", ret);
-- 
2.39.5