[PATCH v5 14/21] KVM: s390: pci: provide routines for enabling/disabling interrupt forwarding

Matthew Rosato
2022-04-04T21:23:46Z

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.

Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
---
arch/s390/kvm/pci.c | 247 +++++++++++++++++++++++++++++++++++++++
arch/s390/kvm/pci.h | 1 +
arch/s390/pci/pci_insn.c | 1 +
3 files changed, 249 insertions(+)

diff --git a/arch/s390/kvm/pci.c b/arch/s390/kvm/pci.c
index 01bd8a2f503b..f0fd68569a9d 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 @@ int kvm_s390_pci_aen_init(u8 nisc)
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;
+}
+
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 d4997e2236ef..b4bf3d1d4b66 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 {
diff --git a/arch/s390/pci/pci_insn.c b/arch/s390/pci/pci_insn.c
index 4c6967b73932..cd9fb186a6be 100644
--- a/arch/s390/pci/pci_insn.c
+++ b/arch/s390/pci/pci_insn.c
@@ -60,6 +60,7 @@ u8 zpci_mod_fc(u64 req, struct zpci_fib *fib, u8 *status)

return cc;
}
+EXPORT_SYMBOL_GPL(zpci_mod_fc);

/* Refresh PCI Translations */
static inline u8 __rpcit(u64 fn, u64 addr, u64 range, u8 *status)
--
2.27.0