KVM: arm64: Use the xarray as the primary sysreg/sysinsn walker

Since we always start sysreg/sysinsn handling by searching the
xarray, use it as the source of the index in the correct sys_reg_desc
array.

This allows some cleanup, such as moving the handling of unknown
sysregs in a single location.

Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20240214131827.2856277-16-maz@kernel.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>

1 files changed, 19 insertions, 44 deletions

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index a410e99f827e..bc076ef8440b 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -3395,12 +3395,6 @@ int kvm_handle_cp14_32(struct kvm_vcpu *vcpu)
 	return kvm_handle_cp_32(vcpu, &params, cp14_regs, ARRAY_SIZE(cp14_regs));
 }
 
-static bool is_imp_def_sys_reg(struct sys_reg_params *params)
-{
-	// See ARM DDI 0487E.a, section D12.3.2
-	return params->Op0 == 3 && (params->CRn & 0b1011) == 0b1011;
-}
-
 /**
  * emulate_sys_reg - Emulate a guest access to an AArch64 system register
  * @vcpu: The VCPU pointer
@@ -3409,44 +3403,22 @@ static bool is_imp_def_sys_reg(struct sys_reg_params *params)
  * Return: true if the system register access was successful, false otherwise.
  */
 static bool emulate_sys_reg(struct kvm_vcpu *vcpu,
-			   struct sys_reg_params *params)
+			    struct sys_reg_params *params)
 {
 	const struct sys_reg_desc *r;
 
 	r = find_reg(params, sys_reg_descs, ARRAY_SIZE(sys_reg_descs));
-
 	if (likely(r)) {
 		perform_access(vcpu, params, r);
 		return true;
 	}
 
-	if (is_imp_def_sys_reg(params)) {
-		kvm_inject_undefined(vcpu);
-	} else {
-		print_sys_reg_msg(params,
-				  "Unsupported guest sys_reg access at: %lx [%08lx]\n",
-				  *vcpu_pc(vcpu), *vcpu_cpsr(vcpu));
-		kvm_inject_undefined(vcpu);
-	}
-	return false;
-}
-
-static int emulate_sys_instr(struct kvm_vcpu *vcpu, struct sys_reg_params *p)
-{
-	const struct sys_reg_desc *r;
-
-	/* Search from the system instruction table. */
-	r = find_reg(p, sys_insn_descs, ARRAY_SIZE(sys_insn_descs));
+	print_sys_reg_msg(params,
+			  "Unsupported guest sys_reg access at: %lx [%08lx]\n",
+			  *vcpu_pc(vcpu), *vcpu_cpsr(vcpu));
+	kvm_inject_undefined(vcpu);
 
-	if (likely(r)) {
-		perform_access(vcpu, p, r);
-	} else {
-		kvm_err("Unsupported guest sys instruction at: %lx\n",
-			*vcpu_pc(vcpu));
-		print_sys_reg_instr(p);
-		kvm_inject_undefined(vcpu);
-	}
-	return 1;
+	return false;
 }
 
 static void kvm_reset_id_regs(struct kvm_vcpu *vcpu)
@@ -3502,31 +3474,34 @@ void kvm_reset_sys_regs(struct kvm_vcpu *vcpu)
  */
 int kvm_handle_sys_reg(struct kvm_vcpu *vcpu)
 {
+	const struct sys_reg_desc *desc = NULL;
 	struct sys_reg_params params;
 	unsigned long esr = kvm_vcpu_get_esr(vcpu);
 	int Rt = kvm_vcpu_sys_get_rt(vcpu);
+	int sr_idx;
 
 	trace_kvm_handle_sys_reg(esr);
 
-	if (__check_nv_sr_forward(vcpu))
+	if (__check_nv_sr_forward(vcpu, &sr_idx))
 		return 1;
 
 	params = esr_sys64_to_params(esr);
 	params.regval = vcpu_get_reg(vcpu, Rt);
 
 	/* System registers have Op0=={2,3}, as per DDI487 J.a C5.1.2 */
-	if (params.Op0 == 2 || params.Op0 == 3) {
-		if (!emulate_sys_reg(vcpu, &params))
-			return 1;
+	if (params.Op0 == 2 || params.Op0 == 3)
+		desc = &sys_reg_descs[sr_idx];
+	else
+		desc = &sys_insn_descs[sr_idx];
 
-		if (!params.is_write)
-			vcpu_set_reg(vcpu, Rt, params.regval);
+	perform_access(vcpu, &params, desc);
 
-		return 1;
-	}
+	/* Read from system register? */
+	if (!params.is_write &&
+	    (params.Op0 == 2 || params.Op0 == 3))
+		vcpu_set_reg(vcpu, Rt, params.regval);
 
-	/* Hints, PSTATE (Op0 == 0) and System instructions (Op0 == 1) */
-	return emulate_sys_instr(vcpu, &params);
+	return 1;
 }
 
 /******************************************************************************