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

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