Message-ID: <e5267f44-5e9a-42a2-a921-5f3428b03c05@os.amperecomputing.com>
Date: Mon, 18 Mar 2024 13:10:31 +0530
From: Ganapatrao Kulkarni <gankulkarni@...amperecomputing.com>
To: Steven Price <steven.price@....com>, kvm@...r.kernel.org,
 kvmarm@...ts.linux.dev
Cc: Catalin Marinas <catalin.marinas@....com>, Marc Zyngier <maz@...nel.org>,
 Will Deacon <will@...nel.org>, James Morse <james.morse@....com>,
 Oliver Upton <oliver.upton@...ux.dev>,
 Suzuki K Poulose <suzuki.poulose@....com>, Zenghui Yu
 <yuzenghui@...wei.com>, linux-arm-kernel@...ts.infradead.org,
 linux-kernel@...r.kernel.org, Joey Gouly <joey.gouly@....com>,
 Alexandru Elisei <alexandru.elisei@....com>,
 Christoffer Dall <christoffer.dall@....com>, Fuad Tabba <tabba@...gle.com>,
 linux-coco@...ts.linux.dev
Subject: Re: [RFC PATCH 06/28] arm64: RME: ioctls to create and configure
 realms



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@....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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