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From:   Matthew Rosato <mjrosato@linux.ibm.com>
To:     linux-s390@vger.kernel.org
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        pasic@linux.ibm.com, joro@8bytes.org, will@kernel.org,
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        kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
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Subject: [PATCH v4 24/32] KVM: s390: pci: provide routines for enabling/disabling interrupt forwarding
Date:   Mon, 14 Mar 2022 15:44:43 -0400
Message-Id: <20220314194451.58266-25-mjrosato@linux.ibm.com>
In-Reply-To: <20220314194451.58266-1-mjrosato@linux.ibm.com>
References: <20220314194451.58266-1-mjrosato@linux.ibm.com>
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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/include/asm/kvm_pci.h |   2 +
 arch/s390/kvm/pci.c             | 201 +++++++++++++++++++++++++++++++-
 arch/s390/pci/pci_insn.c        |   1 +
 3 files changed, 203 insertions(+), 1 deletion(-)

diff --git a/arch/s390/include/asm/kvm_pci.h b/arch/s390/include/asm/kvm_pci.h
index 47ce18b5bddd..ed596880fb06 100644
--- a/arch/s390/include/asm/kvm_pci.h
+++ b/arch/s390/include/asm/kvm_pci.h
@@ -16,11 +16,13 @@
 #include <linux/kvm_host.h>
 #include <linux/kvm.h>
 #include <linux/pci.h>
+#include <asm/pci_insn.h>
 
 struct kvm_zdev {
 	struct zpci_dev *zdev;
 	struct kvm *kvm;
 	struct iommu_domain *dom; /* Used to invoke IOMMU API for RPCIT */
+	struct zpci_fib fib;
 	struct notifier_block nb;
 	struct list_head entry;
 };
diff --git a/arch/s390/kvm/pci.c b/arch/s390/kvm/pci.c
index df50dd6114c3..2287c1c6a3e5 100644
--- a/arch/s390/kvm/pci.c
+++ b/arch/s390/kvm/pci.c
@@ -13,6 +13,7 @@
 #include <asm/kvm_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"
@@ -172,6 +173,200 @@ 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 int kvm_s390_pci_aif_enable(struct zpci_dev *zdev, struct zpci_fib *fib,
+				   bool assist)
+{
+	struct page *aibv_page, *aisb_page = NULL;
+	unsigned int msi_vecs, idx;
+	struct zpci_gaite *gaite;
+	unsigned long bit;
+	struct kvm *kvm;
+	phys_addr_t gaddr;
+	int rc = 0, gisc;
+
+	/*
+	 * 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);
+	aibv_page = gfn_to_page(kvm, gpa_to_gfn((gpa_t)fib->fmt0.aibv));
+	srcu_read_unlock(&kvm->srcu, idx);
+	if (is_error_page(aibv_page)) {
+		rc = -EIO;
+		goto out;
+	}
+	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);
+		aisb_page = gfn_to_page(kvm, gpa_to_gfn((gpa_t)fib->fmt0.aisb));
+		srcu_read_unlock(&kvm->srcu, idx);
+		if (is_error_page(aisb_page)) {
+			rc = -EIO;
+			goto unpin1;
+		}
+	}
+
+	/* 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 unpin2;
+	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;
+
+unpin2:
+	mutex_unlock(&aift->aift_lock);
+	if (fib->fmt0.sum == 1) {
+		gaddr = page_to_phys(aisb_page);
+		kvm_release_pfn_dirty(gaddr >> PAGE_SHIFT);
+	}
+unpin1:
+	kvm_release_pfn_dirty(fib->fmt0.aibv >> PAGE_SHIFT);
+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;
+	int rc;
+	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 */
+		kvm_release_pfn_dirty(kzdev->fib.fmt0.aibv >> PAGE_SHIFT);
+		if (gaite->aisb != 0)
+			kvm_release_pfn_dirty(gaite->aisb >> PAGE_SHIFT);
+		/* 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;
+out:
+	mutex_unlock(&aift->aift_lock);
+
+	return rc;
+}
+
 static int kvm_s390_pci_interp_enable(struct zpci_dev *zdev)
 {
 	u32 gisa;
@@ -226,13 +421,17 @@ static int kvm_s390_pci_interp_enable(struct zpci_dev *zdev)
 	return rc;
 }
 
-static int kvm_s390_pci_interp_disable(struct zpci_dev *zdev)
+static int kvm_s390_pci_interp_disable(struct zpci_dev *zdev, bool force)
 {
 	int rc;
 
 	if (zdev->gisa == 0)
 		return -EINVAL;
 
+	/* Forwarding must be turned off before interpretation */
+	if (zdev->kzdev->fib.fmt0.aibv != 0)
+		kvm_s390_pci_aif_disable(zdev, force);
+
 	/* Remove the host CLP guest designation */
 	zdev->gisa = 0;
 
diff --git a/arch/s390/pci/pci_insn.c b/arch/s390/pci/pci_insn.c
index ca6399d52767..f7d0e29bbf0b 100644
--- a/arch/s390/pci/pci_insn.c
+++ b/arch/s390/pci/pci_insn.c
@@ -59,6 +59,7 @@ 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