On 02/05/2025 12:04, Suzuki K Poulose wrote:
> On 16/04/2025 14:41, Steven Price wrote:
>> The RMM provides emulation of a VGIC to the realm guest but delegates
>> much of the handling to the host. Implement support in KVM for
>> saving/restoring state to/from the REC structure.
>>
>> Signed-off-by: Steven Price <steven.price@xxxxxxx>
>> ---
>> Changes from v5:
>> * Handle RMM providing fewer GIC LRs than the hardware supports.
>> ---
>> arch/arm64/include/asm/kvm_rme.h | 1 +
>> arch/arm64/kvm/arm.c | 16 +++++++++---
>> arch/arm64/kvm/rme.c | 5 ++++
>> arch/arm64/kvm/vgic/vgic-init.c | 2 +-
>> arch/arm64/kvm/vgic/vgic-v3.c | 6 ++++-
>> arch/arm64/kvm/vgic/vgic.c | 43 ++++++++++++++++++++++++++++++--
>> 6 files changed, 66 insertions(+), 7 deletions(-)
>>
>> diff --git a/arch/arm64/include/asm/kvm_rme.h b/arch/arm64/include/
>> asm/kvm_rme.h
>> index f716b890e484..9bcad6ec5dbb 100644
>> --- a/arch/arm64/include/asm/kvm_rme.h
>> +++ b/arch/arm64/include/asm/kvm_rme.h
>> @@ -92,6 +92,7 @@ struct realm_rec {
>> void kvm_init_rme(void);
>> u32 kvm_realm_ipa_limit(void);
>> +u32 kvm_realm_vgic_nr_lr(void);
>> int kvm_realm_enable_cap(struct kvm *kvm, struct kvm_enable_cap
>> *cap);
>> int kvm_init_realm_vm(struct kvm *kvm);
>> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
>> index fd83efb667cc..808d7e479571 100644
>> --- a/arch/arm64/kvm/arm.c
>> +++ b/arch/arm64/kvm/arm.c
>> @@ -683,19 +683,24 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
>> kvm_call_hyp_nvhe(__pkvm_vcpu_put);
>> }
>> + kvm_timer_vcpu_put(vcpu);
>> + kvm_vgic_put(vcpu);
>> +
>> + vcpu->cpu = -1;
>> +
>> + if (vcpu_is_rec(vcpu))
>> + return;
>> +
>> kvm_vcpu_put_debug(vcpu);
>> kvm_arch_vcpu_put_fp(vcpu);
>> if (has_vhe())
>> kvm_vcpu_put_vhe(vcpu);
>> - kvm_timer_vcpu_put(vcpu);
>> - kvm_vgic_put(vcpu);
>> kvm_vcpu_pmu_restore_host(vcpu);
>> if (vcpu_has_nv(vcpu))
>> kvm_vcpu_put_hw_mmu(vcpu);
>> kvm_arm_vmid_clear_active();
>> vcpu_clear_on_unsupported_cpu(vcpu);
>> - vcpu->cpu = -1;
>> }
>> static void __kvm_arm_vcpu_power_off(struct kvm_vcpu *vcpu)
>> @@ -912,6 +917,11 @@ int kvm_arch_vcpu_run_pid_change(struct kvm_vcpu
>> *vcpu)
>> return ret;
>> }
>> + if (!irqchip_in_kernel(kvm) && kvm_is_realm(vcpu->kvm)) {
>> + /* Userspace irqchip not yet supported with Realms */
>> + return -EOPNOTSUPP;
>> + }
>> +
>> mutex_lock(&kvm->arch.config_lock);
>> set_bit(KVM_ARCH_FLAG_HAS_RAN_ONCE, &kvm->arch.flags);
>> mutex_unlock(&kvm->arch.config_lock);
>> diff --git a/arch/arm64/kvm/rme.c b/arch/arm64/kvm/rme.c
>> index f4923fc3b34e..1239eb07aca6 100644
>> --- a/arch/arm64/kvm/rme.c
>> +++ b/arch/arm64/kvm/rme.c
>> @@ -77,6 +77,11 @@ u32 kvm_realm_ipa_limit(void)
>> return u64_get_bits(rmm_feat_reg0, RMI_FEATURE_REGISTER_0_S2SZ);
>> }
>> +u32 kvm_realm_vgic_nr_lr(void)
>> +{
>> + return u64_get_bits(rmm_feat_reg0,
>> RMI_FEATURE_REGISTER_0_GICV3_NUM_LRS);
>> +}
>> +
>> static int get_start_level(struct realm *realm)
>> {
>> return 4 - ((realm->ia_bits - 8) / (RMM_PAGE_SHIFT - 3));
>> diff --git a/arch/arm64/kvm/vgic/vgic-init.c b/arch/arm64/kvm/vgic/
>> vgic-init.c
>> index 1f33e71c2a73..a81c7f3d1d42 100644
>> --- a/arch/arm64/kvm/vgic/vgic-init.c
>> +++ b/arch/arm64/kvm/vgic/vgic-init.c
>> @@ -81,7 +81,7 @@ int kvm_vgic_create(struct kvm *kvm, u32 type)
>> * the proper checks already.
>> */
>> if (type == KVM_DEV_TYPE_ARM_VGIC_V2 &&
>> - !kvm_vgic_global_state.can_emulate_gicv2)
>> + (!kvm_vgic_global_state.can_emulate_gicv2 || kvm_is_realm(kvm)))
>> return -ENODEV;
>> /* Must be held to avoid race with vCPU creation */
>> diff --git a/arch/arm64/kvm/vgic/vgic-v3.c b/arch/arm64/kvm/vgic/vgic-
>> v3.c
>> index b9ad7c42c5b0..c10ad817030d 100644
>> --- a/arch/arm64/kvm/vgic/vgic-v3.c
>> +++ b/arch/arm64/kvm/vgic/vgic-v3.c
>> @@ -8,9 +8,11 @@
>> #include <linux/kvm_host.h>
>> #include <linux/string_choices.h>
>> #include <kvm/arm_vgic.h>
>> +#include <asm/kvm_emulate.h>
>> #include <asm/kvm_hyp.h>
>> #include <asm/kvm_mmu.h>
>> #include <asm/kvm_asm.h>
>> +#include <asm/rmi_smc.h>
>> #include "vgic.h"
>> @@ -758,7 +760,9 @@ void vgic_v3_put(struct kvm_vcpu *vcpu)
>> return;
>> }
>> - if (likely(!is_protected_kvm_enabled()))
>> + if (vcpu_is_rec(vcpu))
>> + cpu_if->vgic_vmcr = vcpu->arch.rec.run->exit.gicv3_vmcr;
>> + else if (likely(!is_protected_kvm_enabled()))
>> kvm_call_hyp(__vgic_v3_save_vmcr_aprs, cpu_if);
>> WARN_ON(vgic_v4_put(vcpu));
>> diff --git a/arch/arm64/kvm/vgic/vgic.c b/arch/arm64/kvm/vgic/vgic.c
>> index 8d189ce18ea0..c68a41a29917 100644
>> --- a/arch/arm64/kvm/vgic/vgic.c
>> +++ b/arch/arm64/kvm/vgic/vgic.c
>> @@ -10,7 +10,9 @@
>> #include <linux/list_sort.h>
>> #include <linux/nospec.h>
>> +#include <asm/kvm_emulate.h>
>> #include <asm/kvm_hyp.h>
>> +#include <asm/kvm_rme.h>
>> #include "vgic.h"
>> @@ -23,6 +25,8 @@ struct vgic_global kvm_vgic_global_state
>> __ro_after_init = {
>> static inline int kvm_vcpu_vgic_nr_lr(struct kvm_vcpu *vcpu)
>> {
>> + if (unlikely(vcpu_is_rec(vcpu)))
>> + return kvm_realm_vgic_nr_lr();
>> return kvm_vgic_global_state.nr_lr;
>> }
>> @@ -864,10 +868,23 @@ static inline bool
>> can_access_vgic_from_kernel(void)
>> return !
>> static_branch_unlikely(&kvm_vgic_global_state.gicv3_cpuif) || has_vhe();
>> }
>> +static inline void vgic_rmm_save_state(struct kvm_vcpu *vcpu)
>> +{
>> + struct vgic_v3_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v3;
>> + int i;
>> +
>> + for (i = 0; i < kvm_vcpu_vgic_nr_lr(vcpu); i++) {
>> + cpu_if->vgic_lr[i] = vcpu->arch.rec.run->exit.gicv3_lrs[i];
>> + vcpu->arch.rec.run->enter.gicv3_lrs[i] = 0;
>> + }
>> +}
>
> We also need to save/restore gicv3_hcr/cpuif->vgic_hcr.
I'm not sure how I missed that. Note that the RMM spec restricts the
fields that the normal world is allowed to set. So I'll also add a new
define to rmi_smc.h to provide the bitmask:
#define RMI_PERMITTED_GICV3_HCR_BITS (ICH_HCR_EL2_UIE | \
ICH_HCR_EL2_LRENPIE | \
ICH_HCR_EL2_NPIE | \
ICH_HCR_EL2_VGrp0EIE | \
ICH_HCR_EL2_VGrp0DIE | \
ICH_HCR_EL2_VGrp1EIE | \
ICH_HCR_EL2_VGrp1DIE | \
ICH_HCR_EL2_TDIR)
>> +
>> static inline void vgic_save_state(struct kvm_vcpu *vcpu)
>> {
>> if (!static_branch_unlikely(&kvm_vgic_global_state.gicv3_cpuif))
>> vgic_v2_save_state(vcpu);
>> + else if (vcpu_is_rec(vcpu))
>> + vgic_rmm_save_state(vcpu);
>> else
>> __vgic_v3_save_state(&vcpu->arch.vgic_cpu.vgic_v3);
>> }
>> @@ -903,10 +920,28 @@ void kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu)
>> vgic_prune_ap_list(vcpu);
>> }
>> +static inline void vgic_rmm_restore_state(struct kvm_vcpu *vcpu)
>> +{
>> + struct vgic_v3_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v3;
>> + int i;
>> +
>> + for (i = 0; i < kvm_vcpu_vgic_nr_lr(vcpu); i++) {
>> + vcpu->arch.rec.run->enter.gicv3_lrs[i] = cpu_if->vgic_lr[i];
>> + /*
>> + * Also populate the rec.run->exit copies so that a late
>> + * decision to back out from entering the realm doesn't cause
>> + * the state to be lost
>> + */
>> + vcpu->arch.rec.run->exit.gicv3_lrs[i] = cpu_if->vgic_lr[i];
>> + }
>> +}
>> +
>> static inline void vgic_restore_state(struct kvm_vcpu *vcpu)
>> {
>> if (!static_branch_unlikely(&kvm_vgic_global_state.gicv3_cpuif))
>> vgic_v2_restore_state(vcpu);
>> + else if (vcpu_is_rec(vcpu))
>> + vgic_rmm_restore_state(vcpu);
>> else
>> __vgic_v3_restore_state(&vcpu->arch.vgic_cpu.vgic_v3);
>> }
>> @@ -976,7 +1011,9 @@ void kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu)
>> void kvm_vgic_load(struct kvm_vcpu *vcpu)
>> {
>> - if (unlikely(!irqchip_in_kernel(vcpu->kvm) || !
>> vgic_initialized(vcpu->kvm))) {
>> + if (unlikely(!irqchip_in_kernel(vcpu->kvm) ||
>> + !vgic_initialized(vcpu->kvm) ||
>> + vcpu_is_rec(vcpu))) {
>
>
>> if (has_vhe() &&
>> static_branch_unlikely(&kvm_vgic_global_state.gicv3_cpuif))
>> __vgic_v3_activate_traps(&vcpu->arch.vgic_cpu.vgic_v3);
>> return;
>> @@ -990,7 +1027,9 @@ void kvm_vgic_load(struct kvm_vcpu *vcpu)
>> void kvm_vgic_put(struct kvm_vcpu *vcpu)
>> {
>> - if (unlikely(!irqchip_in_kernel(vcpu->kvm) || !
>> vgic_initialized(vcpu->kvm))) {
>> + if (unlikely(!irqchip_in_kernel(vcpu->kvm) ||
>> + !vgic_initialized(vcpu->kvm) ||
>> + vcpu_is_rec(vcpu))) {
>> if (has_vhe() &&
>> static_branch_unlikely(&kvm_vgic_global_state.gicv3_cpuif))
>> __vgic_v3_deactivate_traps(&vcpu->arch.vgic_cpu.vgic_v3);
>
> We could return early here for rec, and skip the unnecessary trap steps.
> Similar for the vgic_load case.
Ack. I think this was me getting confused during a rebase ;) I'll pull
out the "if (unlikely(vcpu_is_rec())" and return early.
Steve
> Rest looks good to me.
>
> Suzuki
>
>
>> return;
>
