KVM: s390: pci: provide routines for enabling/disabling interrupt forwarding

These routines will be wired into a kvm ioctl in order to respond to
requests to enable / disable a device for Adapter Event Notifications /
Adapter Interuption Forwarding.

Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Acked-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
Link: https://lore.kernel.org/r/20220606203325.110625-16-mjrosato@linux.ibm.com
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>

2 files changed, 248 insertions, 0 deletions

diff --git a/arch/s390/kvm/pci.c b/arch/s390/kvm/pci.c
index d566551d3018..b232c8cbaa81 100644
--- a/arch/s390/kvm/pci.c
+++ b/arch/s390/kvm/pci.c
@@ -11,6 +11,7 @@
 #include <linux/pci.h>
 #include <asm/pci.h>
 #include <asm/pci_insn.h>
+#include <asm/pci_io.h>
 #include "pci.h"
 
 struct zpci_aift *aift;
@@ -152,6 +153,252 @@ unlock:
 	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;
diff --git a/arch/s390/kvm/pci.h b/arch/s390/kvm/pci.h
index 9f7828d97605..9d091033fc02 100644
--- a/arch/s390/kvm/pci.h
+++ b/arch/s390/kvm/pci.h
@@ -20,6 +20,7 @@
 struct kvm_zdev {
 	struct zpci_dev *zdev;
 	struct kvm *kvm;
+	struct zpci_fib fib;
 };
 
 struct zpci_gaite {