On Thu, Aug 13, 2020 at 02:05:16PM +0800, Peng Liang wrote: > It's time to make ID registers configurable. When userspace (but not > guest) want to set the values of ID registers, save the value in > kvm_arch_vcpu so that guest can read the modified values. > > Signed-off-by: zhanghailiang <[email protected]> > Signed-off-by: Peng Liang <[email protected]> > --- > arch/arm64/kvm/sys_regs.c | 23 ++++++++++++++++------- > 1 file changed, 16 insertions(+), 7 deletions(-) > > diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c > index 776c2757a01e..f98635489966 100644 > --- a/arch/arm64/kvm/sys_regs.c > +++ b/arch/arm64/kvm/sys_regs.c > @@ -1111,6 +1111,14 @@ static u64 kvm_get_id_reg(struct kvm_vcpu *vcpu, u64 > id) > return ri->sys_val; > } > > +static void kvm_set_id_reg(struct kvm_vcpu *vcpu, u64 id, u64 value) > +{ > + struct id_reg_info *ri = kvm_id_reg(vcpu, id); > + > + BUG_ON(!ri); > + ri->sys_val = value; > +} > + > /* Read a sanitised cpufeature ID register by sys_reg_desc */ > static u64 read_id_reg(struct kvm_vcpu *vcpu, > struct sys_reg_desc const *r, bool raz) > @@ -1252,10 +1260,6 @@ static int set_id_aa64zfr0_el1(struct kvm_vcpu *vcpu, > > /* > * cpufeature ID register user accessors > - * > - * For now, these registers are immutable for userspace, so no values > - * are stored, and for set_id_reg() we don't allow the effective value > - * to be changed. > */ > static int __get_id_reg(struct kvm_vcpu *vcpu, > const struct sys_reg_desc *rd, void __user *uaddr, > @@ -1279,9 +1283,14 @@ static int __set_id_reg(struct kvm_vcpu *vcpu, > if (err) > return err; > > - /* This is what we mean by invariant: you can't change it. */ > - if (val != read_id_reg(vcpu, rd, raz)) > - return -EINVAL; > + if (raz) { > + if (val != read_id_reg(vcpu, rd, raz)) > + return -EINVAL; > + } else { > + u32 reg_id = sys_reg((u32)rd->Op0, (u32)rd->Op1, (u32)rd->CRn, > + (u32)rd->CRm, (u32)rd->Op2); > + kvm_set_id_reg(vcpu, reg_id, val);
So userspace can set the ID registers to whatever they want? I think each register should have its own sanity checks applied before accepting the input. Thanks, drew > + } > > return 0; > } > -- > 2.18.4 > _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
