1 files changed, 690 insertions, 0 deletions

diff --git a/arch/s390/kvm/pci.c b/arch/s390/kvm/pci.c
new file mode 100644
index 000000000000..4946fb7757d6
--- /dev/null
+++ b/arch/s390/kvm/pci.c
@@ -0,0 +1,690 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * s390 kvm PCI passthrough support
+ *
+ * Copyright IBM Corp. 2022
+ *
+ *    Author(s): Matthew Rosato <mjrosato@linux.ibm.com>
+ */
+
+#include <linux/kvm_host.h>
+#include <linux/pci.h>
+#include <asm/pci.h>
+#include <asm/pci_insn.h>
+#include <asm/pci_io.h>
+#include <asm/sclp.h>
+#include "pci.h"
+#include "kvm-s390.h"
+
+struct zpci_aift *aift;
+
+static inline int __set_irq_noiib(u16 ctl, u8 isc)
+{
+	union zpci_sic_iib iib = {{0}};
+
+	return zpci_set_irq_ctrl(ctl, isc, &iib);
+}
+
+void kvm_s390_pci_aen_exit(void)
+{
+	unsigned long flags;
+	struct kvm_zdev **gait_kzdev;
+
+	lockdep_assert_held(&aift->aift_lock);
+
+	/*
+	 * Contents of the aipb remain registered for the life of the host
+	 * kernel, the information preserved in zpci_aipb and zpci_aif_sbv
+	 * in case we insert the KVM module again later.  Clear the AIFT
+	 * information and free anything not registered with underlying
+	 * firmware.
+	 */
+	spin_lock_irqsave(&aift->gait_lock, flags);
+	gait_kzdev = aift->kzdev;
+	aift->gait = NULL;
+	aift->sbv = NULL;
+	aift->kzdev = NULL;
+	spin_unlock_irqrestore(&aift->gait_lock, flags);
+
+	kfree(gait_kzdev);
+}
+
+static int zpci_setup_aipb(u8 nisc)
+{
+	struct page *page;
+	int size, rc;
+
+	zpci_aipb = kzalloc(sizeof(union zpci_sic_iib), GFP_KERNEL);
+	if (!zpci_aipb)
+		return -ENOMEM;
+
+	aift->sbv = airq_iv_create(ZPCI_NR_DEVICES, AIRQ_IV_ALLOC, 0);
+	if (!aift->sbv) {
+		rc = -ENOMEM;
+		goto free_aipb;
+	}
+	zpci_aif_sbv = aift->sbv;
+	size = get_order(PAGE_ALIGN(ZPCI_NR_DEVICES *
+						sizeof(struct zpci_gaite)));
+	page = alloc_pages(GFP_KERNEL | __GFP_ZERO, size);
+	if (!page) {
+		rc = -ENOMEM;
+		goto free_sbv;
+	}
+	aift->gait = (struct zpci_gaite *)page_to_phys(page);
+
+	zpci_aipb->aipb.faisb = virt_to_phys(aift->sbv->vector);
+	zpci_aipb->aipb.gait = virt_to_phys(aift->gait);
+	zpci_aipb->aipb.afi = nisc;
+	zpci_aipb->aipb.faal = ZPCI_NR_DEVICES;
+
+	/* Setup Adapter Event Notification Interpretation */
+	if (zpci_set_irq_ctrl(SIC_SET_AENI_CONTROLS, 0, zpci_aipb)) {
+		rc = -EIO;
+		goto free_gait;
+	}
+
+	return 0;
+
+free_gait:
+	free_pages((unsigned long)aift->gait, size);
+free_sbv:
+	airq_iv_release(aift->sbv);
+	zpci_aif_sbv = NULL;
+free_aipb:
+	kfree(zpci_aipb);
+	zpci_aipb = NULL;
+
+	return rc;
+}
+
+static int zpci_reset_aipb(u8 nisc)
+{
+	/*
+	 * AEN registration can only happen once per system boot.  If
+	 * an aipb already exists then AEN was already registered and
+	 * we can re-use the aipb contents.  This can only happen if
+	 * the KVM module was removed and re-inserted.  However, we must
+	 * ensure that the same forwarding ISC is used as this is assigned
+	 * during KVM module load.
+	 */
+	if (zpci_aipb->aipb.afi != nisc)
+		return -EINVAL;
+
+	aift->sbv = zpci_aif_sbv;
+	aift->gait = (struct zpci_gaite *)zpci_aipb->aipb.gait;
+
+	return 0;
+}
+
+int kvm_s390_pci_aen_init(u8 nisc)
+{
+	int rc = 0;
+
+	/* If already enabled for AEN, bail out now */
+	if (aift->gait || aift->sbv)
+		return -EPERM;
+
+	mutex_lock(&aift->aift_lock);
+	aift->kzdev = kcalloc(ZPCI_NR_DEVICES, sizeof(struct kvm_zdev),
+			      GFP_KERNEL);
+	if (!aift->kzdev) {
+		rc = -ENOMEM;
+		goto unlock;
+	}
+
+	if (!zpci_aipb)
+		rc = zpci_setup_aipb(nisc);
+	else
+		rc = zpci_reset_aipb(nisc);
+	if (rc)
+		goto free_zdev;
+
+	/* Enable floating IRQs */
+	if (__set_irq_noiib(SIC_IRQ_MODE_SINGLE, nisc)) {
+		rc = -EIO;
+		kvm_s390_pci_aen_exit();
+	}
+
+	goto unlock;
+
+free_zdev:
+	kfree(aift->kzdev);
+unlock:
+	mutex_unlock(&aift->aift_lock);
+	return rc;
+}
+
+/* Modify PCI: Register floating adapter interruption forwarding */
+static int kvm_zpci_set_airq(struct zpci_dev *zdev)
+{
+	u64 req = ZPCI_CREATE_REQ(zdev->fh, 0, ZPCI_MOD_FC_REG_INT);
+	struct zpci_fib fib = {};
+	u8 status;
+
+	fib.fmt0.isc = zdev->kzdev->fib.fmt0.isc;
+	fib.fmt0.sum = 1;       /* enable summary notifications */
+	fib.fmt0.noi = airq_iv_end(zdev->aibv);
+	fib.fmt0.aibv = virt_to_phys(zdev->aibv->vector);
+	fib.fmt0.aibvo = 0;
+	fib.fmt0.aisb = virt_to_phys(aift->sbv->vector + (zdev->aisb / 64) * 8);
+	fib.fmt0.aisbo = zdev->aisb & 63;
+	fib.gd = zdev->gisa;
+
+	return zpci_mod_fc(req, &fib, &status) ? -EIO : 0;
+}
+
+/* Modify PCI: Unregister floating adapter interruption forwarding */
+static int kvm_zpci_clear_airq(struct zpci_dev *zdev)
+{
+	u64 req = ZPCI_CREATE_REQ(zdev->fh, 0, ZPCI_MOD_FC_DEREG_INT);
+	struct zpci_fib fib = {};
+	u8 cc, status;
+
+	fib.gd = zdev->gisa;
+
+	cc = zpci_mod_fc(req, &fib, &status);
+	if (cc == 3 || (cc == 1 && status == 24))
+		/* Function already gone or IRQs already deregistered. */
+		cc = 0;
+
+	return cc ? -EIO : 0;
+}
+
+static inline void unaccount_mem(unsigned long nr_pages)
+{
+	struct user_struct *user = get_uid(current_user());
+
+	if (user)
+		atomic_long_sub(nr_pages, &user->locked_vm);
+	if (current->mm)
+		atomic64_sub(nr_pages, &current->mm->pinned_vm);
+}
+
+static inline int account_mem(unsigned long nr_pages)
+{
+	struct user_struct *user = get_uid(current_user());
+	unsigned long page_limit, cur_pages, new_pages;
+
+	page_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
+
+	do {
+		cur_pages = atomic_long_read(&user->locked_vm);
+		new_pages = cur_pages + nr_pages;
+		if (new_pages > page_limit)
+			return -ENOMEM;
+	} while (atomic_long_cmpxchg(&user->locked_vm, cur_pages,
+					new_pages) != cur_pages);
+
+	atomic64_add(nr_pages, &current->mm->pinned_vm);
+
+	return 0;
+}
+
+static int kvm_s390_pci_aif_enable(struct zpci_dev *zdev, struct zpci_fib *fib,
+				   bool assist)
+{
+	struct page *pages[1], *aibv_page, *aisb_page = NULL;
+	unsigned int msi_vecs, idx;
+	struct zpci_gaite *gaite;
+	unsigned long hva, bit;
+	struct kvm *kvm;
+	phys_addr_t gaddr;
+	int rc = 0, gisc, npages, pcount = 0;
+
+	/*
+	 * Interrupt forwarding is only applicable if the device is already
+	 * enabled for interpretation
+	 */
+	if (zdev->gisa == 0)
+		return -EINVAL;
+
+	kvm = zdev->kzdev->kvm;
+	msi_vecs = min_t(unsigned int, fib->fmt0.noi, zdev->max_msi);
+
+	/* Get the associated forwarding ISC - if invalid, return the error */
+	gisc = kvm_s390_gisc_register(kvm, fib->fmt0.isc);
+	if (gisc < 0)
+		return gisc;
+
+	/* Replace AIBV address */
+	idx = srcu_read_lock(&kvm->srcu);
+	hva = gfn_to_hva(kvm, gpa_to_gfn((gpa_t)fib->fmt0.aibv));
+	npages = pin_user_pages_fast(hva, 1, FOLL_WRITE | FOLL_LONGTERM, pages);
+	srcu_read_unlock(&kvm->srcu, idx);
+	if (npages < 1) {
+		rc = -EIO;
+		goto out;
+	}
+	aibv_page = pages[0];
+	pcount++;
+	gaddr = page_to_phys(aibv_page) + (fib->fmt0.aibv & ~PAGE_MASK);
+	fib->fmt0.aibv = gaddr;
+
+	/* Pin the guest AISB if one was specified */
+	if (fib->fmt0.sum == 1) {
+		idx = srcu_read_lock(&kvm->srcu);
+		hva = gfn_to_hva(kvm, gpa_to_gfn((gpa_t)fib->fmt0.aisb));
+		npages = pin_user_pages_fast(hva, 1, FOLL_WRITE | FOLL_LONGTERM,
+					     pages);
+		srcu_read_unlock(&kvm->srcu, idx);
+		if (npages < 1) {
+			rc = -EIO;
+			goto unpin1;
+		}
+		aisb_page = pages[0];
+		pcount++;
+	}
+
+	/* Account for pinned pages, roll back on failure */
+	if (account_mem(pcount))
+		goto unpin2;
+
+	/* AISB must be allocated before we can fill in GAITE */
+	mutex_lock(&aift->aift_lock);
+	bit = airq_iv_alloc_bit(aift->sbv);
+	if (bit == -1UL)
+		goto unlock;
+	zdev->aisb = bit; /* store the summary bit number */
+	zdev->aibv = airq_iv_create(msi_vecs, AIRQ_IV_DATA |
+				    AIRQ_IV_BITLOCK |
+				    AIRQ_IV_GUESTVEC,
+				    phys_to_virt(fib->fmt0.aibv));
+
+	spin_lock_irq(&aift->gait_lock);
+	gaite = (struct zpci_gaite *)aift->gait + (zdev->aisb *
+						   sizeof(struct zpci_gaite));
+
+	/* If assist not requested, host will get all alerts */
+	if (assist)
+		gaite->gisa = (u32)virt_to_phys(&kvm->arch.sie_page2->gisa);
+	else
+		gaite->gisa = 0;
+
+	gaite->gisc = fib->fmt0.isc;
+	gaite->count++;
+	gaite->aisbo = fib->fmt0.aisbo;
+	gaite->aisb = virt_to_phys(page_address(aisb_page) + (fib->fmt0.aisb &
+							      ~PAGE_MASK));
+	aift->kzdev[zdev->aisb] = zdev->kzdev;
+	spin_unlock_irq(&aift->gait_lock);
+
+	/* Update guest FIB for re-issue */
+	fib->fmt0.aisbo = zdev->aisb & 63;
+	fib->fmt0.aisb = virt_to_phys(aift->sbv->vector + (zdev->aisb / 64) * 8);
+	fib->fmt0.isc = gisc;
+
+	/* Save some guest fib values in the host for later use */
+	zdev->kzdev->fib.fmt0.isc = fib->fmt0.isc;
+	zdev->kzdev->fib.fmt0.aibv = fib->fmt0.aibv;
+	mutex_unlock(&aift->aift_lock);
+
+	/* Issue the clp to setup the irq now */
+	rc = kvm_zpci_set_airq(zdev);
+	return rc;
+
+unlock:
+	mutex_unlock(&aift->aift_lock);
+unpin2:
+	if (fib->fmt0.sum == 1)
+		unpin_user_page(aisb_page);
+unpin1:
+	unpin_user_page(aibv_page);
+out:
+	return rc;
+}
+
+static int kvm_s390_pci_aif_disable(struct zpci_dev *zdev, bool force)
+{
+	struct kvm_zdev *kzdev = zdev->kzdev;
+	struct zpci_gaite *gaite;
+	struct page *vpage = NULL, *spage = NULL;
+	int rc, pcount = 0;
+	u8 isc;
+
+	if (zdev->gisa == 0)
+		return -EINVAL;
+
+	mutex_lock(&aift->aift_lock);
+
+	/*
+	 * If the clear fails due to an error, leave now unless we know this
+	 * device is about to go away (force) -- In that case clear the GAITE
+	 * regardless.
+	 */
+	rc = kvm_zpci_clear_airq(zdev);
+	if (rc && !force)
+		goto out;
+
+	if (zdev->kzdev->fib.fmt0.aibv == 0)
+		goto out;
+	spin_lock_irq(&aift->gait_lock);
+	gaite = (struct zpci_gaite *)aift->gait + (zdev->aisb *
+						   sizeof(struct zpci_gaite));
+	isc = gaite->gisc;
+	gaite->count--;
+	if (gaite->count == 0) {
+		/* Release guest AIBV and AISB */
+		vpage = phys_to_page(kzdev->fib.fmt0.aibv);
+		if (gaite->aisb != 0)
+			spage = phys_to_page(gaite->aisb);
+		/* Clear the GAIT entry */
+		gaite->aisb = 0;
+		gaite->gisc = 0;
+		gaite->aisbo = 0;
+		gaite->gisa = 0;
+		aift->kzdev[zdev->aisb] = 0;
+		/* Clear zdev info */
+		airq_iv_free_bit(aift->sbv, zdev->aisb);
+		airq_iv_release(zdev->aibv);
+		zdev->aisb = 0;
+		zdev->aibv = NULL;
+	}
+	spin_unlock_irq(&aift->gait_lock);
+	kvm_s390_gisc_unregister(kzdev->kvm, isc);
+	kzdev->fib.fmt0.isc = 0;
+	kzdev->fib.fmt0.aibv = 0;
+
+	if (vpage) {
+		unpin_user_page(vpage);
+		pcount++;
+	}
+	if (spage) {
+		unpin_user_page(spage);
+		pcount++;
+	}
+	if (pcount > 0)
+		unaccount_mem(pcount);
+out:
+	mutex_unlock(&aift->aift_lock);
+
+	return rc;
+}
+
+static int kvm_s390_pci_dev_open(struct zpci_dev *zdev)
+{
+	struct kvm_zdev *kzdev;
+
+	kzdev = kzalloc(sizeof(struct kvm_zdev), GFP_KERNEL);
+	if (!kzdev)
+		return -ENOMEM;
+
+	kzdev->zdev = zdev;
+	zdev->kzdev = kzdev;
+
+	return 0;
+}
+
+static void kvm_s390_pci_dev_release(struct zpci_dev *zdev)
+{
+	struct kvm_zdev *kzdev;
+
+	kzdev = zdev->kzdev;
+	WARN_ON(kzdev->zdev != zdev);
+	zdev->kzdev = NULL;
+	kfree(kzdev);
+}
+
+
+/*
+ * Register device with the specified KVM. If interpetation facilities are
+ * available, enable them and let userspace indicate whether or not they will
+ * be used (specify SHM bit to disable).
+ */
+int kvm_s390_pci_register_kvm(struct zpci_dev *zdev, struct kvm *kvm)
+{
+	int rc;
+
+	if (!zdev)
+		return -EINVAL;
+
+	mutex_lock(&zdev->kzdev_lock);
+
+	if (zdev->kzdev || zdev->gisa != 0 || !kvm) {
+		mutex_unlock(&zdev->kzdev_lock);
+		return -EINVAL;
+	}
+
+	kvm_get_kvm(kvm);
+
+	mutex_lock(&kvm->lock);
+
+	rc = kvm_s390_pci_dev_open(zdev);
+	if (rc)
+		goto err;
+
+	/*
+	 * If interpretation facilities aren't available, add the device to
+	 * the kzdev list but don't enable for interpretation.
+	 */
+	if (!kvm_s390_pci_interp_allowed())
+		goto out;
+
+	/*
+	 * If this is the first request to use an interpreted device, make the
+	 * necessary vcpu changes
+	 */
+	if (!kvm->arch.use_zpci_interp)
+		kvm_s390_vcpu_pci_enable_interp(kvm);
+
+	if (zdev_enabled(zdev)) {
+		rc = zpci_disable_device(zdev);
+		if (rc)
+			goto err;
+	}
+
+	/*
+	 * Store information about the identity of the kvm guest allowed to
+	 * access this device via interpretation to be used by host CLP
+	 */
+	zdev->gisa = (u32)virt_to_phys(&kvm->arch.sie_page2->gisa);
+
+	rc = zpci_enable_device(zdev);
+	if (rc)
+		goto clear_gisa;
+
+	/* Re-register the IOMMU that was already created */
+	rc = zpci_register_ioat(zdev, 0, zdev->start_dma, zdev->end_dma,
+				virt_to_phys(zdev->dma_table));
+	if (rc)
+		goto clear_gisa;
+
+out:
+	zdev->kzdev->kvm = kvm;
+
+	spin_lock(&kvm->arch.kzdev_list_lock);
+	list_add_tail(&zdev->kzdev->entry, &kvm->arch.kzdev_list);
+	spin_unlock(&kvm->arch.kzdev_list_lock);
+
+	mutex_unlock(&kvm->lock);
+	mutex_unlock(&zdev->kzdev_lock);
+	return 0;
+
+clear_gisa:
+	zdev->gisa = 0;
+err:
+	if (zdev->kzdev)
+		kvm_s390_pci_dev_release(zdev);
+	mutex_unlock(&kvm->lock);
+	mutex_unlock(&zdev->kzdev_lock);
+	kvm_put_kvm(kvm);
+	return rc;
+}
+EXPORT_SYMBOL_GPL(kvm_s390_pci_register_kvm);
+
+void kvm_s390_pci_unregister_kvm(struct zpci_dev *zdev)
+{
+	struct kvm *kvm;
+
+	if (!zdev)
+		return;
+
+	mutex_lock(&zdev->kzdev_lock);
+
+	if (WARN_ON(!zdev->kzdev)) {
+		mutex_unlock(&zdev->kzdev_lock);
+		return;
+	}
+
+	kvm = zdev->kzdev->kvm;
+	mutex_lock(&kvm->lock);
+
+	/*
+	 * A 0 gisa means interpretation was never enabled, just remove the
+	 * device from the list.
+	 */
+	if (zdev->gisa == 0)
+		goto out;
+
+	/* Forwarding must be turned off before interpretation */
+	if (zdev->kzdev->fib.fmt0.aibv != 0)
+		kvm_s390_pci_aif_disable(zdev, true);
+
+	/* Remove the host CLP guest designation */
+	zdev->gisa = 0;
+
+	if (zdev_enabled(zdev)) {
+		if (zpci_disable_device(zdev))
+			goto out;
+	}
+
+	if (zpci_enable_device(zdev))
+		goto out;
+
+	/* Re-register the IOMMU that was already created */
+	zpci_register_ioat(zdev, 0, zdev->start_dma, zdev->end_dma,
+			   virt_to_phys(zdev->dma_table));
+
+out:
+	spin_lock(&kvm->arch.kzdev_list_lock);
+	list_del(&zdev->kzdev->entry);
+	spin_unlock(&kvm->arch.kzdev_list_lock);
+	kvm_s390_pci_dev_release(zdev);
+
+	mutex_unlock(&kvm->lock);
+	mutex_unlock(&zdev->kzdev_lock);
+
+	kvm_put_kvm(kvm);
+}
+EXPORT_SYMBOL_GPL(kvm_s390_pci_unregister_kvm);
+
+void kvm_s390_pci_init_list(struct kvm *kvm)
+{
+	spin_lock_init(&kvm->arch.kzdev_list_lock);
+	INIT_LIST_HEAD(&kvm->arch.kzdev_list);
+}
+
+void kvm_s390_pci_clear_list(struct kvm *kvm)
+{
+	/*
+	 * This list should already be empty, either via vfio device closures
+	 * or kvm fd cleanup.
+	 */
+	spin_lock(&kvm->arch.kzdev_list_lock);
+	WARN_ON_ONCE(!list_empty(&kvm->arch.kzdev_list));
+	spin_unlock(&kvm->arch.kzdev_list_lock);
+}
+
+static struct zpci_dev *get_zdev_from_kvm_by_fh(struct kvm *kvm, u32 fh)
+{
+	struct zpci_dev *zdev = NULL;
+	struct kvm_zdev *kzdev;
+
+	spin_lock(&kvm->arch.kzdev_list_lock);
+	list_for_each_entry(kzdev, &kvm->arch.kzdev_list, entry) {
+		if (kzdev->zdev->fh == fh) {
+			zdev = kzdev->zdev;
+			break;
+		}
+	}
+	spin_unlock(&kvm->arch.kzdev_list_lock);
+
+	return zdev;
+}
+
+static int kvm_s390_pci_zpci_reg_aen(struct zpci_dev *zdev,
+				     struct kvm_s390_zpci_op *args)
+{
+	struct zpci_fib fib = {};
+	bool hostflag;
+
+	fib.fmt0.aibv = args->u.reg_aen.ibv;
+	fib.fmt0.isc = args->u.reg_aen.isc;
+	fib.fmt0.noi = args->u.reg_aen.noi;
+	if (args->u.reg_aen.sb != 0) {
+		fib.fmt0.aisb = args->u.reg_aen.sb;
+		fib.fmt0.aisbo = args->u.reg_aen.sbo;
+		fib.fmt0.sum = 1;
+	} else {
+		fib.fmt0.aisb = 0;
+		fib.fmt0.aisbo = 0;
+		fib.fmt0.sum = 0;
+	}
+
+	hostflag = !(args->u.reg_aen.flags & KVM_S390_ZPCIOP_REGAEN_HOST);
+	return kvm_s390_pci_aif_enable(zdev, &fib, hostflag);
+}
+
+int kvm_s390_pci_zpci_op(struct kvm *kvm, struct kvm_s390_zpci_op *args)
+{
+	struct kvm_zdev *kzdev;
+	struct zpci_dev *zdev;
+	int r;
+
+	zdev = get_zdev_from_kvm_by_fh(kvm, args->fh);
+	if (!zdev)
+		return -ENODEV;
+
+	mutex_lock(&zdev->kzdev_lock);
+	mutex_lock(&kvm->lock);
+
+	kzdev = zdev->kzdev;
+	if (!kzdev) {
+		r = -ENODEV;
+		goto out;
+	}
+	if (kzdev->kvm != kvm) {
+		r = -EPERM;
+		goto out;
+	}
+
+	switch (args->op) {
+	case KVM_S390_ZPCIOP_REG_AEN:
+		/* Fail on unknown flags */
+		if (args->u.reg_aen.flags & ~KVM_S390_ZPCIOP_REGAEN_HOST) {
+			r = -EINVAL;
+			break;
+		}
+		r = kvm_s390_pci_zpci_reg_aen(zdev, args);
+		break;
+	case KVM_S390_ZPCIOP_DEREG_AEN:
+		r = kvm_s390_pci_aif_disable(zdev, false);
+		break;
+	default:
+		r = -EINVAL;
+	}
+
+out:
+	mutex_unlock(&kvm->lock);
+	mutex_unlock(&zdev->kzdev_lock);
+	return r;
+}
+
+int kvm_s390_pci_init(void)
+{
+	aift = kzalloc(sizeof(struct zpci_aift), GFP_KERNEL);
+	if (!aift)
+		return -ENOMEM;
+
+	spin_lock_init(&aift->gait_lock);
+	mutex_init(&aift->aift_lock);
+
+	return 0;
+}
+
+void kvm_s390_pci_exit(void)
+{
+	mutex_destroy(&aift->aift_lock);
+
+	kfree(aift);
+}