Hi Dave,
On 18/02/2019 19:52, Dave Martin wrote:
@@ -1091,6 +1088,95 @@ static int reg_from_user(u64 *val, const void __user *uaddr, u64 id);
static int reg_to_user(void __user *uaddr, const u64 *val, u64 id);
static u64 sys_reg_to_index(const struct sys_reg_desc *reg);
+static unsigned int sve_restrictions(const struct kvm_vcpu *vcpu,
+ const struct sys_reg_desc *rd)
+{
+ return vcpu_has_sve(vcpu) ? 0 : REG_NO_USER | REG_NO_GUEST;
+}
+
+static unsigned int sve_id_restrictions(const struct kvm_vcpu *vcpu,
+ const struct sys_reg_desc *rd)
+{
+ return vcpu_has_sve(vcpu) ? 0 : REG_NO_USER;
+}
+
+static int get_zcr_el1(struct kvm_vcpu *vcpu,
+ const struct sys_reg_desc *rd,
+ const struct kvm_one_reg *reg, void __user *uaddr)
+{
+ if (WARN_ON(!vcpu_has_sve(vcpu)))
+ return -ENOENT;
+
+ return reg_to_user(uaddr, &vcpu->arch.ctxt.sys_regs[ZCR_EL1],
+ reg->id);
+}
+
+static int set_zcr_el1(struct kvm_vcpu *vcpu,
+ const struct sys_reg_desc *rd,
+ const struct kvm_one_reg *reg, void __user *uaddr)
+{
+ if (WARN_ON(!vcpu_has_sve(vcpu)))
+ return -ENOENT;
+
+ return reg_from_user(&vcpu->arch.ctxt.sys_regs[ZCR_EL1], uaddr,
+ reg->id);
+}
+
+/* Generate the emulated ID_AA64ZFR0_EL1 value exposed to the guest */
+static u64 guest_id_aa64zfr0_el1(const struct kvm_vcpu *vcpu)
+{
+ if (!vcpu_has_sve(vcpu))
+ return 0;
+
+ return read_sanitised_ftr_reg(SYS_ID_AA64ZFR0_EL1);
+}
+
+static bool access_id_aa64zfr0_el1(struct kvm_vcpu *vcpu,
+ struct sys_reg_params *p,
+ const struct sys_reg_desc *rd)
+{
+ if (p->is_write)
+ return write_to_read_only(vcpu, p, rd);
+
+ p->regval = guest_id_aa64zfr0_el1(vcpu);
+ return true;
+}
+
+static int get_id_aa64zfr0_el1(struct kvm_vcpu *vcpu,
+ const struct sys_reg_desc *rd,
+ const struct kvm_one_reg *reg, void __user *uaddr)
+{
+ u64 val;
+
+ if (!vcpu_has_sve(vcpu))
+ return -ENOENT;
+
+ val = guest_id_aa64zfr0_el1(vcpu);
+ return reg_to_user(uaddr, &val, reg->id);
+}
+
+static int set_id_aa64zfr0_el1(struct kvm_vcpu *vcpu,
+ const struct sys_reg_desc *rd,
+ const struct kvm_one_reg *reg, void __user *uaddr)
+{
+ const u64 id = sys_reg_to_index(rd);
+ int err;
+ u64 val;
+
+ if (!vcpu_has_sve(vcpu))
+ return -ENOENT;
+
+ err = reg_from_user(&val, uaddr, id);
+ if (err)
+ return err;
+
+ /* This is what we mean by invariant: you can't change it. */
+ if (val != guest_id_aa64zfr0_el1(vcpu))
+ return -EINVAL;
+
+ return 0;
+}
We seem to already have code for handling invariant registers as well as reading
ID register. I guess the only reason you can't use them is because of the check
the vcpu is using SVE.
However, AFAICT the restrictions callback would prevent you to enter the {get,
set}_id if the vCPU does not support SVE. So the check should not be reachable.
Did I miss anything?
Cheers,
--
Julien Grall
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