Hi,
On Mon, Feb 19, 2024 at 09:20:05AM +0000, Marc Zyngier wrote:
> Add the HCR_EL2 configuration for FEAT_NV2, adding the required
> bits for running a guest hypervisor, and overall merging the
> allowed bits provided by the guest.
>
> This heavily replies on unavaliable features being sanitised
> when the HCR_EL2 shadow register is accessed, and only a couple
> of bits must be explicitly disabled.
>
> Non-NV guests are completely unaffected by any of this.
>
> Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
> ---
> arch/arm64/include/asm/sysreg.h | 1 +
> arch/arm64/kvm/hyp/include/hyp/switch.h | 4 +--
> arch/arm64/kvm/hyp/nvhe/switch.c | 2 +-
> arch/arm64/kvm/hyp/vhe/switch.c | 34 ++++++++++++++++++++++++-
> 4 files changed, 36 insertions(+), 5 deletions(-)
>
> diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
> index 9e8999592f3a..a5361d9032a4 100644
> --- a/arch/arm64/include/asm/sysreg.h
> +++ b/arch/arm64/include/asm/sysreg.h
> @@ -498,6 +498,7 @@
> #define SYS_TCR_EL2 sys_reg(3, 4, 2, 0, 2)
> #define SYS_VTTBR_EL2 sys_reg(3, 4, 2, 1, 0)
> #define SYS_VTCR_EL2 sys_reg(3, 4, 2, 1, 2)
> +#define SYS_VNCR_EL2 sys_reg(3, 4, 2, 2, 0)
>
> #define SYS_TRFCR_EL2 sys_reg(3, 4, 1, 2, 1)
> #define SYS_VNCR_EL2 sys_reg(3, 4, 2, 2, 0)
I'm seeing double! (SYS_VNCR_EL2 is already defined a few lines down)
> diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h
> index e3fcf8c4d5b4..f5f701f309a9 100644
> --- a/arch/arm64/kvm/hyp/include/hyp/switch.h
> +++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
> @@ -271,10 +271,8 @@ static inline void __deactivate_traps_common(struct kvm_vcpu *vcpu)
> __deactivate_traps_hfgxtr(vcpu);
> }
>
> -static inline void ___activate_traps(struct kvm_vcpu *vcpu)
> +static inline void ___activate_traps(struct kvm_vcpu *vcpu, u64 hcr)
> {
> - u64 hcr = vcpu->arch.hcr_el2;
> -
> if (cpus_have_final_cap(ARM64_WORKAROUND_CAVIUM_TX2_219_TVM))
> hcr |= HCR_TVM;
>
> diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c
> index c50f8459e4fc..4103625e46c5 100644
> --- a/arch/arm64/kvm/hyp/nvhe/switch.c
> +++ b/arch/arm64/kvm/hyp/nvhe/switch.c
> @@ -40,7 +40,7 @@ static void __activate_traps(struct kvm_vcpu *vcpu)
> {
> u64 val;
>
> - ___activate_traps(vcpu);
> + ___activate_traps(vcpu, vcpu->arch.hcr_el2);
> __activate_traps_common(vcpu);
>
> val = vcpu->arch.cptr_el2;
> diff --git a/arch/arm64/kvm/hyp/vhe/switch.c b/arch/arm64/kvm/hyp/vhe/switch.c
> index 58415783fd53..29f59c374f7a 100644
> --- a/arch/arm64/kvm/hyp/vhe/switch.c
> +++ b/arch/arm64/kvm/hyp/vhe/switch.c
> @@ -33,11 +33,43 @@ DEFINE_PER_CPU(struct kvm_host_data, kvm_host_data);
> DEFINE_PER_CPU(struct kvm_cpu_context, kvm_hyp_ctxt);
> DEFINE_PER_CPU(unsigned long, kvm_hyp_vector);
>
> +/*
> + * HCR_EL2 bits that the NV guest can freely change (no RES0/RES1
> + * semantics, irrespective of the configuration), but that cannot be
> + * applied to the actual HW as things would otherwise break badly.
> + *
> + * - TGE: we want to use EL1, which is incompatible with it being set
Can you make this a bit clearer:
we want the guest to use EL1
Assuming I've understood correctly. I first read it as 'we' == kvm.
> + *
> + * - API/APK: for hysterical raisins, we enable PAuth lazily, which
> + * means that the guest's bits cannot be directly applied (we really
> + * want to see the traps). Revisit this at some point.
> + */
> +#define NV_HCR_GUEST_EXCLUDE (HCR_TGE | HCR_API | HCR_APK)
> +
> +static u64 __compute_hcr(struct kvm_vcpu *vcpu)
> +{
> + u64 hcr = vcpu->arch.hcr_el2;
> +
> + if (!vcpu_has_nv(vcpu))
> + return hcr;
> +
> + if (is_hyp_ctxt(vcpu)) {
> + hcr |= HCR_NV | HCR_NV2 | HCR_AT | HCR_TTLB;
> +
> + if (!vcpu_el2_e2h_is_set(vcpu))
> + hcr |= HCR_NV1;
> +
> + write_sysreg_s(vcpu->arch.ctxt.vncr_array, SYS_VNCR_EL2);
> + }
> +
> + return hcr | (__vcpu_sys_reg(vcpu, HCR_EL2) & ~NV_HCR_GUEST_EXCLUDE);
> +}
> +
> static void __activate_traps(struct kvm_vcpu *vcpu)
> {
> u64 val;
>
> - ___activate_traps(vcpu);
> + ___activate_traps(vcpu, __compute_hcr(vcpu));
>
> if (has_cntpoff()) {
> struct timer_map map;
Otherwise,
Reviewed-by: Joey Gouly <joey.gouly@xxxxxxx>
Thanks,
Joey
