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SubjectRe: [RFC PATCH v2 35/38] KVM: arm64: Respect the virtual HCR_EL2.NV bit setting for EL12 register traps
On Tue, Jul 18, 2017 at 11:59:01AM -0500, Jintack Lim wrote:
> In addition to EL2 register accesses, setting NV bit will also make EL12
> register accesses trap to EL2. To emulate this for the virtual EL2,
> forword traps due to EL12 register accessses to the virtual EL2 if the
> virtual HCR_EL2.NV bit is set.
>
> This is for recursive nested virtualization.

>
> Signed-off-by: Jintack Lim <jintack.lim@linaro.org>
> ---
> arch/arm64/kvm/sys_regs.c | 18 ++++++++++++++++++
> 1 file changed, 18 insertions(+)
>
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index 4fd7090..3559cf7 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -149,6 +149,9 @@ static bool access_vm_reg(struct kvm_vcpu *vcpu,
> int i;
> const struct el1_el2_map *map;
>
> + if (el12_reg(p) && forward_nv_traps(vcpu))
> + return kvm_inject_nested_sync(vcpu, kvm_vcpu_get_hsr(vcpu));
> +
> /*
> * Redirect EL1 register accesses to the corresponding EL2 registers if
> * they are meant to access EL2 registers.
> @@ -959,6 +962,9 @@ static bool access_cntkctl_el12(struct kvm_vcpu *vcpu,
> struct sys_reg_params *p,
> const struct sys_reg_desc *r)
> {
> + if (forward_nv_traps(vcpu))
> + return kvm_inject_nested_sync(vcpu, kvm_vcpu_get_hsr(vcpu));
> +
> access_rw(p, &vcpu_sys_reg(vcpu, r->reg));
> return true;
> }
> @@ -1005,6 +1011,9 @@ static bool access_elr(struct kvm_vcpu *vcpu,
> struct sys_reg_params *p,
> const struct sys_reg_desc *r)
> {
> + if (el12_reg(p) && forward_nv_traps(vcpu))
> + return kvm_inject_nested_sync(vcpu, kvm_vcpu_get_hsr(vcpu));
> +
> access_rw(p, &vcpu->arch.ctxt.gp_regs.elr_el1);
> return true;
> }
> @@ -1013,6 +1022,9 @@ static bool access_spsr(struct kvm_vcpu *vcpu,
> struct sys_reg_params *p,
> const struct sys_reg_desc *r)
> {
> + if (el12_reg(p) && forward_nv_traps(vcpu))
> + return kvm_inject_nested_sync(vcpu, kvm_vcpu_get_hsr(vcpu));
> +
> access_rw(p, &vcpu->arch.ctxt.gp_regs.spsr[KVM_SPSR_EL1]);
> return true;
> }
> @@ -1021,6 +1033,9 @@ static bool access_vbar(struct kvm_vcpu *vcpu,
> struct sys_reg_params *p,
> const struct sys_reg_desc *r)
> {
> + if (el12_reg(p) && forward_nv_traps(vcpu))
> + return kvm_inject_nested_sync(vcpu, kvm_vcpu_get_hsr(vcpu));
> +
> access_rw(p, &vcpu_sys_reg(vcpu, r->reg));
> return true;
> }
> @@ -1031,6 +1046,9 @@ static bool access_cpacr(struct kvm_vcpu *vcpu,
> {
> u64 reg = sys_reg(p->Op0, p->Op1, p->CRn, p->CRm, p->Op2);
>
> + if (el12_reg(p) && forward_nv_traps(vcpu))
> + return kvm_inject_nested_sync(vcpu, kvm_vcpu_get_hsr(vcpu));
> +
> /*
> * When the virtual HCR_EL2.E2H == 1, an access to CPACR_EL1
> * in the virtual EL2 is to access CPTR_EL2.
> --
> 1.9.1
>

I'm wondering instead of having all these handlers, could we add this at
a higher level, like kvm_handle_sys() instead?

Thanks,
-Christoffer

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