[RFC 17/55] KVM: arm64: Trap SPSR_EL1, ELR_EL1 and VBAR_EL1 in virtual EL2

Christoffer Dall
2017-02-22T11:40:26Z

On Mon, Jan 09, 2017 at 01:24:13AM -0500, Jintack Lim wrote:
> For the same reason we trap virtual memory register accesses in virtual
> EL2, we need to trap SPSR_EL1, ELR_EL1 and VBAR_EL1 accesses. ARM v8.3
> introduces the HCR_EL2.NV1 bit to be able to trap on those register
> accesses in EL1. Do not set this bit until the whole nesting support is
> complete.

You'll only enable this feature for a non-VHE guest hypervisor, right?

>
> Signed-off-by: Jintack Lim <jintack@cs.columbia.edu>
> ---
> arch/arm64/kvm/sys_regs.c | 41 ++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 40 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index 0f5d21b..19d6a6e 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -898,6 +898,38 @@ static bool access_cntp_cval(struct kvm_vcpu *vcpu,
> return true;
> }
>
> +static inline void access_rw(struct sys_reg_params *p, u64 *sysreg)
> +{
> + if (!p->is_write)
> + p->regval = *sysreg;
> + else
> + *sysreg = p->regval;
> +}
> +
> +static bool access_elr(struct kvm_vcpu *vcpu,
> + struct sys_reg_params *p,
> + const struct sys_reg_desc *r)
> +{
> + access_rw(p, &vcpu->arch.ctxt.gp_regs.elr_el1);
> + return true;
> +}
> +
> +static bool access_spsr(struct kvm_vcpu *vcpu,
> + struct sys_reg_params *p,
> + const struct sys_reg_desc *r)
> +{
> + access_rw(p, &vcpu->arch.ctxt.gp_regs.spsr[KVM_SPSR_EL1]);
> + return true;
> +}
> +
> +static bool access_vbar(struct kvm_vcpu *vcpu,
> + struct sys_reg_params *p,
> + const struct sys_reg_desc *r)
> +{
> + access_rw(p, &vcpu_sys_reg(vcpu, r->reg));
> + return true;
> +}
> +
> static bool trap_el2_reg(struct kvm_vcpu *vcpu,
> struct sys_reg_params *p,
> const struct sys_reg_desc *r)
> @@ -1013,6 +1045,13 @@ static bool trap_el2_reg(struct kvm_vcpu *vcpu,
> { Op0(0b11), Op1(0b000), CRn(0b0010), CRm(0b0000), Op2(0b010),
> access_vm_reg, reset_val, TCR_EL1, 0 },
>
> + /* SPSR_EL1 */
> + { Op0(0b11), Op1(0b000), CRn(0b0100), CRm(0b0000), Op2(0b000),
> + access_spsr},
> + /* ELR_EL1 */
> + { Op0(0b11), Op1(0b000), CRn(0b0100), CRm(0b0000), Op2(0b001),
> + access_elr},
> +
> /* AFSR0_EL1 */
> { Op0(0b11), Op1(0b000), CRn(0b0101), CRm(0b0001), Op2(0b000),
> access_vm_reg, reset_unknown, AFSR0_EL1 },
> @@ -1045,7 +1084,7 @@ static bool trap_el2_reg(struct kvm_vcpu *vcpu,
>
> /* VBAR_EL1 */
> { Op0(0b11), Op1(0b000), CRn(0b1100), CRm(0b0000), Op2(0b000),
> - NULL, reset_val, VBAR_EL1, 0 },
> + access_vbar, reset_val, VBAR_EL1, 0 },
>
> /* ICC_SGI1R_EL1 */
> { Op0(0b11), Op1(0b000), CRn(0b1100), CRm(0b1011), Op2(0b101),
> --
> 1.9.1
>
>