kvm: arm64: emulate the ID registers

hulk inclusion
category: feature
bugzilla: 48052
CVE: NA

------------------------------

To emulate the ID registers, we need a place to storage the values of
the ID regsiters.  Maybe putting in kvm_arch_vcpu is a good idea.

This commit has no functional changes but only code refactor.  When
initializing a vcpu, get the values of the ID registers from
arm64_ftr_regs and storage them in kvm_arch_vcpu.  And we just read
the value from kvm_arch_vcpu when getting/setting the value of the ID
regs.
Signed-off-by: Nzhanghailiang <zhang.zhanghailiang@huawei.com>
Signed-off-by: NPeng Liang <liangpeng10@huawei.com>
Reviewed-by: NZhanghailiang <zhang.zhanghailiang@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

arch/arm64/include/asm/kvm_host.h

@@ -387,6 +387,8 @@ struct kvm_vcpu_arch {
 		bool pv_unhalted;
 		gpa_t base;
 	} pvsched;
+
+	struct id_registers idregs;
 };
 
 /* Pointer to the vcpu's SVE FFR for sve_{save,load}_state() */

arch/arm64/kvm/arm.c

@@ -269,6 +269,24 @@ int kvm_arch_vcpu_precreate(struct kvm *kvm, unsigned int id)
 	return 0;
 }
 
+static int get_cpu_ftr(u32 id, u64 val, void *argp)
+{
+	struct id_registers *idregs = argp;
+
+	/*
+	 * (Op0, Op1, CRn, CRm, Op2) of ID registers is (3, 0, 0, crm, op2),
+	 * where 1<=crm<8, 0<=op2<8.
+	 */
+	if (sys_reg_Op0(id) == 3 && sys_reg_Op1(id) == 0 &&
+	    sys_reg_CRn(id) == 0 && sys_reg_CRm(id) > 0) {
+		idregs->regs[idregs->num].sys_id = id;
+		idregs->regs[idregs->num].sys_val = val;
+		idregs->num++;
+	}
+
+	return 0;
+}
+
 int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
 {
 	int err;
@@ -296,6 +314,10 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
 	if (err)
 		return err;
 
+	err = arm64_cpu_ftr_regs_traverse(get_cpu_ftr, &vcpu->arch.idregs);
+	if (err)
+		return err;
+
 	return create_hyp_mappings(vcpu, vcpu + 1, PAGE_HYP);
 }
 

arch/arm64/kvm/sys_regs.c

@@ -1112,13 +1112,35 @@ static bool access_arch_timer(struct kvm_vcpu *vcpu,
 	return true;
 }
 
+static struct id_reg_info *kvm_id_reg(struct kvm_vcpu *vcpu, u64 id)
+{
+	int i;
+
+	for (i = 0; i < vcpu->arch.idregs.num; ++i) {
+		if (vcpu->arch.idregs.regs[i].sys_id == id)
+			return &vcpu->arch.idregs.regs[i];
+	}
+	return NULL;
+}
+
+static u64 kvm_get_id_reg(struct kvm_vcpu *vcpu, u64 id)
+{
+	struct id_reg_info *ri = kvm_id_reg(vcpu, id);
+
+	if (!ri) {
+		WARN_ON(1);
+		return 0;
+	}
+	return ri->sys_val;
+}
+
 /* Read a sanitised cpufeature ID register by sys_reg_desc */
-static u64 read_id_reg(const struct kvm_vcpu *vcpu,
+static u64 read_id_reg(struct kvm_vcpu *vcpu,
 		struct sys_reg_desc const *r, bool raz)
 {
 	u32 id = sys_reg((u32)r->Op0, (u32)r->Op1,
 			 (u32)r->CRn, (u32)r->CRm, (u32)r->Op2);
-	u64 val = raz ? 0 : read_sanitised_ftr_reg(id);
+	u64 val = raz ? 0 : kvm_get_id_reg(vcpu, id);
 
 	if (id == SYS_ID_AA64PFR0_EL1) {
 		if (!vcpu_has_sve(vcpu))
@@ -1249,7 +1271,7 @@ static int set_id_aa64pfr0_el1(struct kvm_vcpu *vcpu,
  * are stored, and for set_id_reg() we don't allow the effective value
  * to be changed.
  */
-static int __get_id_reg(const struct kvm_vcpu *vcpu,
+static int __get_id_reg(struct kvm_vcpu *vcpu,
 			const struct sys_reg_desc *rd, void __user *uaddr,
 			bool raz)
 {
@@ -1259,7 +1281,7 @@ static int __get_id_reg(const struct kvm_vcpu *vcpu,
 	return reg_to_user(uaddr, &val, id);
 }
 
-static int __set_id_reg(const struct kvm_vcpu *vcpu,
+static int __set_id_reg(struct kvm_vcpu *vcpu,
 			const struct sys_reg_desc *rd, void __user *uaddr,
 			bool raz)
 {

include/uapi/linux/kvm.h

@@ -1298,6 +1298,17 @@ struct kvm_vfio_spapr_tce {
 	__s32	tablefd;
 };
 
+#define ID_REG_MAX_NUMS 64
+struct id_reg_info {
+	__u64 sys_id;
+	__u64 sys_val;
+};
+
+struct id_registers {
+	struct id_reg_info regs[ID_REG_MAX_NUMS];
+	__u64 num;
+};
+
 /*
  * ioctls for VM fds
  */