Re: [RFC PATCH 06/28] arm64: RME: ioctls to create and configure realms

Ganapatrao Kulkarni
2024-03-18T07:40:48Z

On 27-01-2023 04:59 pm, Steven Price wrote:
> Add the KVM_CAP_ARM_RME_CREATE_FD ioctl to create a realm. This involves
> delegating pages to the RMM to hold the Realm Descriptor (RD) and for
> the base level of the Realm Translation Tables (RTT). A VMID also need
> to be picked, since the RMM has a separate VMID address space a
> dedicated allocator is added for this purpose.
>
> KVM_CAP_ARM_RME_CONFIG_REALM is provided to allow configuring the realm
> before it is created.
>
> Signed-off-by: Steven Price <steven.price@arm.com>
> ---
> arch/arm64/include/asm/kvm_rme.h | 14 ++
> arch/arm64/kvm/arm.c | 19 ++
> arch/arm64/kvm/mmu.c | 6 +
> arch/arm64/kvm/reset.c | 33 +++
> arch/arm64/kvm/rme.c | 357 +++++++++++++++++++++++++++++++
> 5 files changed, 429 insertions(+)
>
> diff --git a/arch/arm64/include/asm/kvm_rme.h b/arch/arm64/include/asm/kvm_rme.h
> index c26bc2c6770d..055a22accc08 100644
> --- a/arch/arm64/include/asm/kvm_rme.h
> +++ b/arch/arm64/include/asm/kvm_rme.h
> @@ -6,6 +6,8 @@
> #ifndef __ASM_KVM_RME_H
> #define __ASM_KVM_RME_H
>
> +#include <uapi/linux/kvm.h>
> +
> enum realm_state {
> REALM_STATE_NONE,
> REALM_STATE_NEW,
> @@ -15,8 +17,20 @@ enum realm_state {
>
> struct realm {
> enum realm_state state;
> +
> + void *rd;
> + struct realm_params *params;
> +
> + unsigned long num_aux;
> + unsigned int vmid;
> + unsigned int ia_bits;
> };
>
> int kvm_init_rme(void);
> +u32 kvm_realm_ipa_limit(void);
> +
> +int kvm_realm_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap);
> +int kvm_init_realm_vm(struct kvm *kvm);
> +void kvm_destroy_realm(struct kvm *kvm);
>
> #endif
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index d97b39d042ab..50f54a63732a 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -103,6 +103,13 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
> r = 0;
> set_bit(KVM_ARCH_FLAG_SYSTEM_SUSPEND_ENABLED, &kvm->arch.flags);
> break;
> + case KVM_CAP_ARM_RME:
> + if (!static_branch_unlikely(&kvm_rme_is_available))
> + return -EINVAL;
> + mutex_lock(&kvm->lock);
> + r = kvm_realm_enable_cap(kvm, cap);
> + mutex_unlock(&kvm->lock);
> + break;
> default:
> r = -EINVAL;
> break;
> @@ -172,6 +179,13 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
> */
> kvm->arch.dfr0_pmuver.imp = kvm_arm_pmu_get_pmuver_limit();
>
> + /* Initialise the realm bits after the generic bits are enabled */
> + if (kvm_is_realm(kvm)) {
> + ret = kvm_init_realm_vm(kvm);
> + if (ret)
> + goto err_free_cpumask;
> + }
> +
> return 0;
>
> err_free_cpumask:
> @@ -204,6 +218,8 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
> kvm_destroy_vcpus(kvm);
>
> kvm_unshare_hyp(kvm, kvm + 1);
> +
> + kvm_destroy_realm(kvm);
> }
>
> int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
> @@ -300,6 +316,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
> case KVM_CAP_ARM_PTRAUTH_GENERIC:
> r = system_has_full_ptr_auth();
> break;
> + case KVM_CAP_ARM_RME:
> + r = static_key_enabled(&kvm_rme_is_available);
> + break;
> default:
> r = 0;
> }
> diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> index 31d7fa4c7c14..d0f707767d05 100644
> --- a/arch/arm64/kvm/mmu.c
> +++ b/arch/arm64/kvm/mmu.c
> @@ -840,6 +840,12 @@ void kvm_free_stage2_pgd(struct kvm_s2_mmu *mmu)
> struct kvm_pgtable *pgt = NULL;
>
> write_lock(&kvm->mmu_lock);
> + if (kvm_is_realm(kvm) &&
> + kvm_realm_state(kvm) != REALM_STATE_DYING) {
> + /* TODO: teardown rtts */
> + write_unlock(&kvm->mmu_lock);
> + return;
> + }
> pgt = mmu->pgt;
> if (pgt) {
> mmu->pgd_phys = 0;
> diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
> index e0267f672b8a..c165df174737 100644
> --- a/arch/arm64/kvm/reset.c
> +++ b/arch/arm64/kvm/reset.c
> @@ -395,3 +395,36 @@ int kvm_set_ipa_limit(void)
>
> return 0;
> }
> +
> +int kvm_arm_setup_stage2(struct kvm *kvm, unsigned long type)
> +{
> + u64 mmfr0, mmfr1;
> + u32 phys_shift;
> + u32 ipa_limit = kvm_ipa_limit;
> +
> + if (kvm_is_realm(kvm))
> + ipa_limit = kvm_realm_ipa_limit();
> +
> + if (type & ~KVM_VM_TYPE_ARM_IPA_SIZE_MASK)
> + return -EINVAL;
> +
> + phys_shift = KVM_VM_TYPE_ARM_IPA_SIZE(type);
> + if (phys_shift) {
> + if (phys_shift > ipa_limit ||
> + phys_shift < ARM64_MIN_PARANGE_BITS)
> + return -EINVAL;
> + } else {
> + phys_shift = KVM_PHYS_SHIFT;
> + if (phys_shift > ipa_limit) {
> + pr_warn_once("%s using unsupported default IPA limit, upgrade your VMM\n",
> + current->comm);
> + return -EINVAL;
> + }
> + }
> +
> + mmfr0 = read_sanitised_ftr_reg(SYS_ID_AA64MMFR0_EL1);
> + mmfr1 = read_sanitised_ftr_reg(SYS_ID_AA64MMFR1_EL1);
> + kvm->arch.vtcr = kvm_get_vtcr(mmfr0, mmfr1, phys_shift);
> +
> + return 0;
> +}
> diff --git a/arch/arm64/kvm/rme.c b/arch/arm64/kvm/rme.c
> index f6b587bc116e..9f8c5a91b8fc 100644
> --- a/arch/arm64/kvm/rme.c
> +++ b/arch/arm64/kvm/rme.c
> @@ -5,9 +5,49 @@
>
> #include <linux/kvm_host.h>
>
> +#include <asm/kvm_emulate.h>
> +#include <asm/kvm_mmu.h>
> #include <asm/rmi_cmds.h>
> #include <asm/virt.h>
>
> +/************ FIXME: Copied from kvm/hyp/pgtable.c **********/
> +#include <asm/kvm_pgtable.h>
> +
> +struct kvm_pgtable_walk_data {
> + struct kvm_pgtable *pgt;
> + struct kvm_pgtable_walker *walker;
> +
> + u64 addr;
> + u64 end;
> +};
> +
> +static u32 __kvm_pgd_page_idx(struct kvm_pgtable *pgt, u64 addr)
> +{
> + u64 shift = kvm_granule_shift(pgt->start_level - 1); /* May underflow */
> + u64 mask = BIT(pgt->ia_bits) - 1;
> +
> + return (addr & mask) >> shift;
> +}
> +
> +static u32 kvm_pgd_pages(u32 ia_bits, u32 start_level)
> +{
> + struct kvm_pgtable pgt = {
> + .ia_bits = ia_bits,
> + .start_level = start_level,
> + };
> +
> + return __kvm_pgd_page_idx(&pgt, -1ULL) + 1;
> +}
> +
> +/******************/
> +
> +static unsigned long rmm_feat_reg0;
> +
> +static bool rme_supports(unsigned long feature)
> +{
> + return !!u64_get_bits(rmm_feat_reg0, feature);
> +}
> +
> static int rmi_check_version(void)
> {
> struct arm_smccc_res res;
> @@ -33,8 +73,319 @@ static int rmi_check_version(void)
> return 0;
> }
>
> +static unsigned long create_realm_feat_reg0(struct kvm *kvm)
> +{
> + unsigned long ia_bits = VTCR_EL2_IPA(kvm->arch.vtcr);
> + u64 feat_reg0 = 0;
> +
> + int num_bps = u64_get_bits(rmm_feat_reg0,
> + RMI_FEATURE_REGISTER_0_NUM_BPS);
> + int num_wps = u64_get_bits(rmm_feat_reg0,
> + RMI_FEATURE_REGISTER_0_NUM_WPS);
> +
> + feat_reg0 |= u64_encode_bits(ia_bits, RMI_FEATURE_REGISTER_0_S2SZ);
> + feat_reg0 |= u64_encode_bits(num_bps, RMI_FEATURE_REGISTER_0_NUM_BPS);
> + feat_reg0 |= u64_encode_bits(num_wps, RMI_FEATURE_REGISTER_0_NUM_WPS);
> +
> + return feat_reg0;
> +}
> +
> +u32 kvm_realm_ipa_limit(void)
> +{
> + return u64_get_bits(rmm_feat_reg0, RMI_FEATURE_REGISTER_0_S2SZ);
> +}
> +
> +static u32 get_start_level(struct kvm *kvm)
> +{
> + long sl0 = FIELD_GET(VTCR_EL2_SL0_MASK, kvm->arch.vtcr);
> +
> + return VTCR_EL2_TGRAN_SL0_BASE - sl0;
> +}
> +
> +static int realm_create_rd(struct kvm *kvm)
> +{
> + struct realm *realm = &kvm->arch.realm;
> + struct realm_params *params = realm->params;
> + void *rd = NULL;
> + phys_addr_t rd_phys, params_phys;
> + struct kvm_pgtable *pgt = kvm->arch.mmu.pgt;
> + unsigned int pgd_sz;
> + int i, r;
> +
> + if (WARN_ON(realm->rd) || WARN_ON(!realm->params))
> + return -EEXIST;
> +
> + rd = (void *)__get_free_page(GFP_KERNEL);
> + if (!rd)
> + return -ENOMEM;
> +
> + rd_phys = virt_to_phys(rd);
> + if (rmi_granule_delegate(rd_phys)) {
> + r = -ENXIO;
> + goto out;
> + }
> +
> + pgd_sz = kvm_pgd_pages(pgt->ia_bits, pgt->start_level);
> + for (i = 0; i < pgd_sz; i++) {
> + phys_addr_t pgd_phys = kvm->arch.mmu.pgd_phys + i * PAGE_SIZE;
> +
> + if (rmi_granule_delegate(pgd_phys)) {
> + r = -ENXIO;
> + goto out_undelegate_tables;
> + }
> + }
> +
> + params->rtt_level_start = get_start_level(kvm);
> + params->rtt_num_start = pgd_sz;
> + params->rtt_base = kvm->arch.mmu.pgd_phys;
> + params->vmid = realm->vmid;
> +
> + params_phys = virt_to_phys(params);
> +
> + if (rmi_realm_create(rd_phys, params_phys)) {
> + r = -ENXIO;
> + goto out_undelegate_tables;
> + }
> +
> + realm->rd = rd;
> + realm->ia_bits = VTCR_EL2_IPA(kvm->arch.vtcr);
> +
> + if (WARN_ON(rmi_rec_aux_count(rd_phys, &realm->num_aux))) {
> + WARN_ON(rmi_realm_destroy(rd_phys));
> + goto out_undelegate_tables;
> + }
> +
> + return 0;
> +
> +out_undelegate_tables:
> + while (--i >= 0) {
> + phys_addr_t pgd_phys = kvm->arch.mmu.pgd_phys + i * PAGE_SIZE;
> +
> + WARN_ON(rmi_granule_undelegate(pgd_phys));
> + }
> + WARN_ON(rmi_granule_undelegate(rd_phys));
> +out:
> + free_page((unsigned long)rd);
> + return r;
> +}
> +
> +/* Protects access to rme_vmid_bitmap */
> +static DEFINE_SPINLOCK(rme_vmid_lock);
> +static unsigned long *rme_vmid_bitmap;
> +
> +static int rme_vmid_init(void)
> +{
> + unsigned int vmid_count = 1 << kvm_get_vmid_bits();
> +
> + rme_vmid_bitmap = bitmap_zalloc(vmid_count, GFP_KERNEL);
> + if (!rme_vmid_bitmap) {
> + kvm_err("%s: Couldn't allocate rme vmid bitmap\n", __func__);
> + return -ENOMEM;
> + }
> +
> + return 0;
> +}
> +
> +static int rme_vmid_reserve(void)
> +{
> + int ret;
> + unsigned int vmid_count = 1 << kvm_get_vmid_bits();
> +
> + spin_lock(&rme_vmid_lock);
> + ret = bitmap_find_free_region(rme_vmid_bitmap, vmid_count, 0);
> + spin_unlock(&rme_vmid_lock);
> +
> + return ret;
> +}
> +
> +static void rme_vmid_release(unsigned int vmid)
> +{
> + spin_lock(&rme_vmid_lock);
> + bitmap_release_region(rme_vmid_bitmap, vmid, 0);
> + spin_unlock(&rme_vmid_lock);
> +}
> +
> +static int kvm_create_realm(struct kvm *kvm)
> +{
> + struct realm *realm = &kvm->arch.realm;
> + int ret;
> +
> + if (!kvm_is_realm(kvm) || kvm_realm_state(kvm) != REALM_STATE_NONE)
> + return -EEXIST;
> +
> + ret = rme_vmid_reserve();
> + if (ret < 0)
> + return ret;
> + realm->vmid = ret;
> +
> + ret = realm_create_rd(kvm);
> + if (ret) {
> + rme_vmid_release(realm->vmid);
> + return ret;
> + }
> +
> + WRITE_ONCE(realm->state, REALM_STATE_NEW);
> +
> + /* The realm is up, free the parameters. */
> + free_page((unsigned long)realm->params);
> + realm->params = NULL;
> +
> + return 0;
> +}
> +
> +static int config_realm_hash_algo(struct realm *realm,
> + struct kvm_cap_arm_rme_config_item *cfg)
> +{
> + switch (cfg->hash_algo) {
> + case KVM_CAP_ARM_RME_MEASUREMENT_ALGO_SHA256:
> + if (!rme_supports(RMI_FEATURE_REGISTER_0_HASH_SHA_256))
> + return -EINVAL;
> + break;
> + case KVM_CAP_ARM_RME_MEASUREMENT_ALGO_SHA512:
> + if (!rme_supports(RMI_FEATURE_REGISTER_0_HASH_SHA_512))
> + return -EINVAL;
> + break;
> + default:
> + return -EINVAL;
> + }
> + realm->params->measurement_algo = cfg->hash_algo;
> + return 0;
> +}
> +
> +static int config_realm_sve(struct realm *realm,
> + struct kvm_cap_arm_rme_config_item *cfg)
> +{
> + u64 features_0 = realm->params->features_0;
> + int max_sve_vq = u64_get_bits(rmm_feat_reg0,
> + RMI_FEATURE_REGISTER_0_SVE_VL);
> +
> + if (!rme_supports(RMI_FEATURE_REGISTER_0_SVE_EN))
> + return -EINVAL;
> +
> + if (cfg->sve_vq > max_sve_vq)
> + return -EINVAL;
> +
> + features_0 &= ~(RMI_FEATURE_REGISTER_0_SVE_EN |
> + RMI_FEATURE_REGISTER_0_SVE_VL);
> + features_0 |= u64_encode_bits(1, RMI_FEATURE_REGISTER_0_SVE_EN);
> + features_0 |= u64_encode_bits(cfg->sve_vq,
> + RMI_FEATURE_REGISTER_0_SVE_VL);
> +
> + realm->params->features_0 = features_0;
> + return 0;
> +}
> +
> +static int kvm_rme_config_realm(struct kvm *kvm, struct kvm_enable_cap *cap)
> +{
> + struct kvm_cap_arm_rme_config_item cfg;
> + struct realm *realm = &kvm->arch.realm;
> + int r = 0;
> +
> + if (kvm_realm_state(kvm) != REALM_STATE_NONE)
> + return -EBUSY;
> +
> + if (copy_from_user(&cfg, (void __user *)cap->args[1], sizeof(cfg)))
> + return -EFAULT;
> +
> + switch (cfg.cfg) {
> + case KVM_CAP_ARM_RME_CFG_RPV:
> + memcpy(&realm->params->rpv, &cfg.rpv, sizeof(cfg.rpv));
> + break;
> + case KVM_CAP_ARM_RME_CFG_HASH_ALGO:
> + r = config_realm_hash_algo(realm, &cfg);
> + break;
> + case KVM_CAP_ARM_RME_CFG_SVE:
> + r = config_realm_sve(realm, &cfg);
> + break;
> + default:
> + r = -EINVAL;
> + }
> +
> + return r;
> +}
> +
> +int kvm_realm_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap)
> +{
> + int r = 0;
> +
> + switch (cap->args[0]) {
> + case KVM_CAP_ARM_RME_CONFIG_REALM:
> + r = kvm_rme_config_realm(kvm, cap);
> + break;
> + case KVM_CAP_ARM_RME_CREATE_RD:
> + if (kvm->created_vcpus) {
> + r = -EBUSY;
> + break;
> + }
> +
> + r = kvm_create_realm(kvm);
> + break;
> + default:
> + r = -EINVAL;
> + break;
> + }
> +
> + return r;
> +}
> +
> +void kvm_destroy_realm(struct kvm *kvm)
> +{
> + struct realm *realm = &kvm->arch.realm;
> + struct kvm_pgtable *pgt = kvm->arch.mmu.pgt;
> + unsigned int pgd_sz;
> + int i;
> +
> + if (realm->params) {
> + free_page((unsigned long)realm->params);
> + realm->params = NULL;
> + }
> +
> + if (kvm_realm_state(kvm) == REALM_STATE_NONE)
> + return;
> +
> + WRITE_ONCE(realm->state, REALM_STATE_DYING);
> +
> + rme_vmid_release(realm->vmid);
> +
> + if (realm->rd) {
> + phys_addr_t rd_phys = virt_to_phys(realm->rd);
> +
> + if (WARN_ON(rmi_realm_destroy(rd_phys)))
> + return;
> + if (WARN_ON(rmi_granule_undelegate(rd_phys)))
> + return;
> + free_page((unsigned long)realm->rd);
> + realm->rd = NULL;
> + }
> +
> + pgd_sz = kvm_pgd_pages(pgt->ia_bits, pgt->start_level);
> + for (i = 0; i < pgd_sz; i++) {
> + phys_addr_t pgd_phys = kvm->arch.mmu.pgd_phys + i * PAGE_SIZE;
> +
> + if (WARN_ON(rmi_granule_undelegate(pgd_phys)))
> + return;
> + }
> +
> + kvm_free_stage2_pgd(&kvm->arch.mmu);
> +}
> +
> +int kvm_init_realm_vm(struct kvm *kvm)
> +{
> + struct realm_params *params;
> +
> + params = (struct realm_params *)get_zeroed_page(GFP_KERNEL);
> + if (!params)
> + return -ENOMEM;
> +
> + params->features_0 = create_realm_feat_reg0(kvm);
> + kvm->arch.realm.params = params;
> + return 0;
> +}
> +
> int kvm_init_rme(void)
> {
> + int ret;
> +
> if (PAGE_SIZE != SZ_4K)
> /* Only 4k page size on the host is supported */
> return 0;
> @@ -43,6 +394,12 @@ int kvm_init_rme(void)
> /* Continue without realm support */
> return 0;
>
> + ret = rme_vmid_init();
> + if (ret)
> + return ret;
> +
> + WARN_ON(rmi_features(0, &rmm_feat_reg0));

Why WARN_ON, Is that good enough to print err/info message and keep
"kvm_rme_is_available" disabled?

IMO, we should print message when rme is enabled, otherwise it should be
silent return.

> +
> /* Future patch will enable static branch kvm_rme_is_available */
>
> return 0;

Thanks,
Ganapat