[PATCH 12/37] KVM: arm64: Factor out fault info population and gic workarounds

[Christoffer Dall]

The current world-switch function has functionality to detect a number
of cases where we need to fixup some part of the exit condition and
possibly run the guest again, before having restored the host state.

This includes populating missing fault info, emulating GICv2 CPU
interface accesses when mapped at unaligned addresses, and emulating
the GICv3 CPU interfaceon systems that need that.

As we are about to have an alternative switch function for VHE systems,
but VHE systems still need the same early fixup logic, factor out this
logic into a separate function that can be shared by both switch
functions.

No functional change.

Signed-off-by: Christoffer Dall <christoffer.dall at linaro.org>
---
 arch/arm64/kvm/hyp/switch.c | 91 ++++++++++++++++++++++++++-------------------
 1 file changed, 52 insertions(+), 39 deletions(-)

diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c
index e270cba..ed30af5 100644
--- a/arch/arm64/kvm/hyp/switch.c
+++ b/arch/arm64/kvm/hyp/switch.c
@@ -258,50 +258,24 @@ static void __hyp_text __skip_instr(struct kvm_vcpu *vcpu)
 	write_sysreg_el2(*vcpu_pc(vcpu), elr);
 }
 
-int __hyp_text __kvm_vcpu_run(struct kvm_vcpu *vcpu)
+/*
+ * Return true when we were able to fixup the guest exit and should return to
+ * the guest, false when we should restore the host state and return to the
+ * main run loop.
+ */
+static bool __hyp_text fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code)
 {
-	struct kvm_cpu_context *host_ctxt;
-	struct kvm_cpu_context *guest_ctxt;
-	u64 exit_code;
-
-	vcpu = kern_hyp_va(vcpu);
-
-	host_ctxt = kern_hyp_va(vcpu->arch.host_cpu_context);
-	host_ctxt->__hyp_running_vcpu = vcpu;
-	guest_ctxt = &vcpu->arch.ctxt;
-
-	__sysreg_save_host_state(host_ctxt);
-
-	__activate_traps(vcpu);
-	__activate_vm(vcpu);
-
-	__vgic_restore_state(vcpu);
-	__timer_enable_traps(vcpu);
-
-	/*
-	 * We must restore the 32-bit state before the sysregs, thanks
-	 * to erratum #852523 (Cortex-A57) or #853709 (Cortex-A72).
-	 */
-	__sysreg32_restore_state(vcpu);
-	__sysreg_restore_guest_state(guest_ctxt);
-	__debug_switch_to_guest(vcpu);
-
-	/* Jump in the fire! */
-again:
-	exit_code = __guest_enter(vcpu, host_ctxt);
-	/* And we're baaack! */
-
 	/*
 	 * We're using the raw exception code in order to only process
 	 * the trap if no SError is pending. We will come back to the
 	 * same PC once the SError has been injected, and replay the
 	 * trapping instruction.
 	 */
-	if (exit_code == ARM_EXCEPTION_TRAP && !__populate_fault_info(vcpu))
-		goto again;
+	if (*exit_code == ARM_EXCEPTION_TRAP && !__populate_fault_info(vcpu))
+		return true;
 
 	if (static_branch_unlikely(&vgic_v2_cpuif_trap) &&
-	    exit_code == ARM_EXCEPTION_TRAP) {
+	    *exit_code == ARM_EXCEPTION_TRAP) {
 		bool valid;
 
 		valid = kvm_vcpu_trap_get_class(vcpu) == ESR_ELx_EC_DABT_LOW &&
@@ -315,13 +289,13 @@ int __hyp_text __kvm_vcpu_run(struct kvm_vcpu *vcpu)
 
 			if (ret == 1) {
 				__skip_instr(vcpu);
-				goto again;
+				return true;
 			}
 
 			if (ret == -1) {
 				/* Promote an illegal access to an SError */
 				__skip_instr(vcpu);
-				exit_code = ARM_EXCEPTION_EL1_SERROR;
+				*exit_code = ARM_EXCEPTION_EL1_SERROR;
 			}
 
 			/* 0 falls through to be handler out of EL2 */
@@ -329,19 +303,58 @@ int __hyp_text __kvm_vcpu_run(struct kvm_vcpu *vcpu)
 	}
 
 	if (static_branch_unlikely(&vgic_v3_cpuif_trap) &&
-	    exit_code == ARM_EXCEPTION_TRAP &&
+	    *exit_code == ARM_EXCEPTION_TRAP &&
 	    (kvm_vcpu_trap_get_class(vcpu) == ESR_ELx_EC_SYS64 ||
 	     kvm_vcpu_trap_get_class(vcpu) == ESR_ELx_EC_CP15_32)) {
 		int ret = __vgic_v3_perform_cpuif_access(vcpu);
 
 		if (ret == 1) {
 			__skip_instr(vcpu);
-			goto again;
+			return true;
 		}
 
 		/* 0 falls through to be handled out of EL2 */
 	}
 
+	return false;
+}
+
+int __hyp_text __kvm_vcpu_run(struct kvm_vcpu *vcpu)
+{
+	struct kvm_cpu_context *host_ctxt;
+	struct kvm_cpu_context *guest_ctxt;
+	u64 exit_code;
+
+	vcpu = kern_hyp_va(vcpu);
+
+	host_ctxt = kern_hyp_va(vcpu->arch.host_cpu_context);
+	host_ctxt->__hyp_running_vcpu = vcpu;
+	guest_ctxt = &vcpu->arch.ctxt;
+
+	__sysreg_save_host_state(host_ctxt);
+
+	__activate_traps(vcpu);
+	__activate_vm(vcpu);
+
+	__vgic_restore_state(vcpu);
+	__timer_enable_traps(vcpu);
+
+	/*
+	 * We must restore the 32-bit state before the sysregs, thanks
+	 * to erratum #852523 (Cortex-A57) or #853709 (Cortex-A72).
+	 */
+	__sysreg32_restore_state(vcpu);
+	__sysreg_restore_guest_state(guest_ctxt);
+	__debug_switch_to_guest(vcpu);
+
+	/* Jump in the fire! */
+again:
+	exit_code = __guest_enter(vcpu, host_ctxt);
+	/* And we're baaack! */
+
+	if (fixup_guest_exit(vcpu, &exit_code))
+		goto again;
+
 	__sysreg_save_guest_state(guest_ctxt);
 	__sysreg32_save_state(vcpu);
 	__timer_disable_traps(vcpu);
-- 
2.9.0