[PATCH 42/59] KVM: arm64: nv: Rework the system instruction emulation framework

[Marc Zyngier <marc.zyngier@xxxxxxx>]

From: Jintack Lim <jintack.lim@xxxxxxxxxx>

Rework the system instruction emulation framework to handle potentially
all system instruction traps other than MSR/MRS instructions. Those
system instructions would be AT and TLBI instructions controlled by
HCR_EL2.NV, AT, and TTLB bits.

Signed-off-by: Jintack Lim <jintack.lim@xxxxxxxxxx>
[Changed to use a generic forward_traps wrapper for forward_nv_traps]
Signed-off-by: Christoffer Dall <christoffer.dall@xxxxxxx>
Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
---
 arch/arm64/kvm/sys_regs.c | 62 ++++++++++++++++++---------------------
 1 file changed, 28 insertions(+), 34 deletions(-)

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 8fbb04ddde11..0d5b7a7c76de 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1656,7 +1656,6 @@ static bool access_sp_el1(struct kvm_vcpu *vcpu,
 	return true;
 }
 
-
 /* This function is to support the recursive nested virtualization */
 static bool forward_nv1_traps(struct kvm_vcpu *vcpu, struct sys_reg_params *p)
 {
@@ -1703,6 +1702,12 @@ static bool access_spsr_el2(struct kvm_vcpu *vcpu,
 			    struct sys_reg_params *p,
 			    const struct sys_reg_desc *r)
 {
+	if (el12_reg(p) && forward_nv_traps(vcpu))
+		return false;
+
+	if (!el12_reg(p) && forward_nv1_traps(vcpu, p))
+		return false;
+
 	if (p->is_write)
 		vcpu_write_sys_reg(vcpu, p->regval, SPSR_EL2);
 	else
@@ -1786,10 +1791,6 @@ static bool access_id_aa64pfr0_el1(struct kvm_vcpu *v,
  * more demanding guest...
  */
 static const struct sys_reg_desc sys_reg_descs[] = {
-	{ SYS_DESC(SYS_DC_ISW), access_dcsw },
-	{ SYS_DESC(SYS_DC_CSW), access_dcsw },
-	{ SYS_DESC(SYS_DC_CISW), access_dcsw },
-
 	DBG_BCR_BVR_WCR_WVR_EL1(0),
 	DBG_BCR_BVR_WCR_WVR_EL1(1),
 	{ SYS_DESC(SYS_MDCCINT_EL1), trap_debug_regs, reset_val, MDCCINT_EL1, 0 },
@@ -2134,6 +2135,14 @@ static const struct sys_reg_desc sys_reg_descs[] = {
 	{ SYS_DESC(SYS_SP_EL2), NULL, reset_unknown, SP_EL2 },
 };
 
+#define SYS_INSN_TO_DESC(insn, access_fn, forward_fn)	\
+	{ SYS_DESC((insn)), (access_fn), NULL, 0, 0, NULL, NULL, (forward_fn) }
+static struct sys_reg_desc sys_insn_descs[] = {
+	{ SYS_DESC(SYS_DC_ISW), access_dcsw },
+	{ SYS_DESC(SYS_DC_CSW), access_dcsw },
+	{ SYS_DESC(SYS_DC_CISW), access_dcsw },
+};
+
 static bool trap_dbgidr(struct kvm_vcpu *vcpu,
 			struct sys_reg_params *p,
 			const struct sys_reg_desc *r)
@@ -2755,38 +2764,22 @@ static int emulate_sys_reg(struct kvm_vcpu *vcpu,
 	return 1;
 }
 
-static int emulate_tlbi(struct kvm_vcpu *vcpu,
-			     struct sys_reg_params *params)
+static int emulate_sys_instr(struct kvm_vcpu *vcpu, struct sys_reg_params *p)
 {
-	/* TODO: support tlbi instruction emulation*/
-	kvm_inject_undefined(vcpu);
-	return 1;
-}
-
-static int emulate_at(struct kvm_vcpu *vcpu,
-			     struct sys_reg_params *params)
-{
-	/* TODO: support address translation instruction emulation */
-	kvm_inject_undefined(vcpu);
-	return 1;
-}
-
-static int emulate_sys_instr(struct kvm_vcpu *vcpu,
-			     struct sys_reg_params *params)
-{
-	int ret = 0;
-
-	/* TLB maintenance instructions*/
-	if (params->CRn == 0b1000)
-		ret = emulate_tlbi(vcpu, params);
-	/* Address Translation instructions */
-	else if (params->CRn == 0b0111 && params->CRm == 0b1000)
-		ret = emulate_at(vcpu, params);
+	const struct sys_reg_desc *r;
 
-	if (ret)
-		kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
+	/* Search from the system instruction table. */
+	r = find_reg(p, sys_insn_descs, ARRAY_SIZE(sys_insn_descs));
 
-	return ret;
+	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;
 }
 
 static void reset_sys_reg_descs(struct kvm_vcpu *vcpu,
@@ -3282,6 +3275,7 @@ void kvm_sys_reg_table_init(void)
 	BUG_ON(check_sysreg_table(cp15_regs, ARRAY_SIZE(cp15_regs)));
 	BUG_ON(check_sysreg_table(cp15_64_regs, ARRAY_SIZE(cp15_64_regs)));
 	BUG_ON(check_sysreg_table(invariant_sys_regs, ARRAY_SIZE(invariant_sys_regs)));
+	BUG_ON(check_sysreg_table(sys_insn_descs, ARRAY_SIZE(sys_insn_descs)));
 
 	/* We abuse the reset function to overwrite the table itself. */
 	for (i = 0; i < ARRAY_SIZE(invariant_sys_regs); i++)
-- 
2.20.1