[PATCH v3 21/30] KVM: s390: pci: provide routines for enabling/disabling IOAT assist

[Matthew Rosato]

These routines will be wired into the vfio_pci_zdev ioctl handlers to
respond to requests to enable / disable a device for PCI I/O Address
Translation assistance.

Signed-off-by: Matthew Rosato <mjrosato@xxxxxxxxxxxxx>
---
 arch/s390/include/asm/kvm_pci.h |  15 ++++
 arch/s390/include/asm/pci_dma.h |   2 +
 arch/s390/kvm/pci.c             | 142 ++++++++++++++++++++++++++++++++
 arch/s390/kvm/pci.h             |   2 +
 4 files changed, 161 insertions(+)

diff --git a/arch/s390/include/asm/kvm_pci.h b/arch/s390/include/asm/kvm_pci.h
index 377eebcba2d1..370d6ba041fe 100644
--- a/arch/s390/include/asm/kvm_pci.h
+++ b/arch/s390/include/asm/kvm_pci.h
@@ -15,11 +15,21 @@
 #include <linux/kvm_host.h>
 #include <linux/kvm.h>
 #include <linux/pci.h>
+#include <linux/mutex.h>
 #include <asm/pci_insn.h>
+#include <asm/pci_dma.h>
+
+struct kvm_zdev_ioat {
+	unsigned long *head[ZPCI_TABLE_PAGES];
+	unsigned long **seg;
+	unsigned long ***pt;
+	struct mutex ioat_lock; /* Must be held when modifying head/seg/pt */
+};
 
 struct kvm_zdev {
 	struct zpci_dev *zdev;
 	struct kvm *kvm;
+	struct kvm_zdev_ioat ioat;
 	struct zpci_fib fib;
 };
 
@@ -31,6 +41,11 @@ int kvm_s390_pci_aif_enable(struct zpci_dev *zdev, struct zpci_fib *fib,
 			    bool assist);
 int kvm_s390_pci_aif_disable(struct zpci_dev *zdev, bool force);
 
+int kvm_s390_pci_ioat_probe(struct zpci_dev *zdev);
+int kvm_s390_pci_ioat_enable(struct zpci_dev *zdev, u64 iota);
+int kvm_s390_pci_ioat_disable(struct zpci_dev *zdev);
+u8 kvm_s390_pci_get_dtsm(struct zpci_dev *zdev);
+
 int kvm_s390_pci_interp_probe(struct zpci_dev *zdev);
 int kvm_s390_pci_interp_enable(struct zpci_dev *zdev);
 int kvm_s390_pci_interp_disable(struct zpci_dev *zdev, bool force);
diff --git a/arch/s390/include/asm/pci_dma.h b/arch/s390/include/asm/pci_dma.h
index 91e63426bdc5..69e616d0712c 100644
--- a/arch/s390/include/asm/pci_dma.h
+++ b/arch/s390/include/asm/pci_dma.h
@@ -50,6 +50,8 @@ enum zpci_ioat_dtype {
 #define ZPCI_TABLE_ALIGN		ZPCI_TABLE_SIZE
 #define ZPCI_TABLE_ENTRY_SIZE		(sizeof(unsigned long))
 #define ZPCI_TABLE_ENTRIES		(ZPCI_TABLE_SIZE / ZPCI_TABLE_ENTRY_SIZE)
+#define ZPCI_TABLE_PAGES		(ZPCI_TABLE_SIZE >> PAGE_SHIFT)
+#define ZPCI_TABLE_ENTRIES_PAGES	(ZPCI_TABLE_ENTRIES * ZPCI_TABLE_PAGES)
 
 #define ZPCI_TABLE_BITS			11
 #define ZPCI_PT_BITS			8
diff --git a/arch/s390/kvm/pci.c b/arch/s390/kvm/pci.c
index 8e9044a7bce7..fa9d6ac1755b 100644
--- a/arch/s390/kvm/pci.c
+++ b/arch/s390/kvm/pci.c
@@ -13,12 +13,15 @@
 #include <asm/pci.h>
 #include <asm/pci_insn.h>
 #include <asm/pci_io.h>
+#include <asm/pci_dma.h>
 #include <asm/sclp.h>
 #include "pci.h"
 #include "kvm-s390.h"
 
 struct zpci_aift *aift;
 
+#define shadow_ioat_init zdev->kzdev->ioat.head[0]
+
 static inline int __set_irq_noiib(u16 ctl, u8 isc)
 {
 	union zpci_sic_iib iib = {{0}};
@@ -366,6 +369,138 @@ int kvm_s390_pci_aif_disable(struct zpci_dev *zdev, bool force)
 }
 EXPORT_SYMBOL_GPL(kvm_s390_pci_aif_disable);
 
+int kvm_s390_pci_ioat_probe(struct zpci_dev *zdev)
+{
+	/*
+	 * Using the IOAT assist is only valid for a device with a KVM guest
+	 * registered
+	 */
+	if (!zdev->kzdev->kvm)
+		return -EINVAL;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(kvm_s390_pci_ioat_probe);
+
+int kvm_s390_pci_ioat_enable(struct zpci_dev *zdev, u64 iota)
+{
+	gpa_t gpa = (gpa_t)(iota & ZPCI_RTE_ADDR_MASK);
+	struct kvm_zdev_ioat *ioat;
+	struct page *page;
+	struct kvm *kvm;
+	unsigned int idx;
+	void *iaddr;
+	int i, rc;
+
+	if (shadow_ioat_init)
+		return -EINVAL;
+
+	/* Ensure supported type specified */
+	if ((iota & ZPCI_IOTA_RTTO_FLAG) != ZPCI_IOTA_RTTO_FLAG)
+		return -EINVAL;
+
+	kvm = zdev->kzdev->kvm;
+	ioat = &zdev->kzdev->ioat;
+	mutex_lock(&ioat->ioat_lock);
+	idx = srcu_read_lock(&kvm->srcu);
+	for (i = 0; i < ZPCI_TABLE_PAGES; i++) {
+		page = gfn_to_page(kvm, gpa_to_gfn(gpa));
+		if (is_error_page(page)) {
+			srcu_read_unlock(&kvm->srcu, idx);
+			rc = -EIO;
+			goto unpin;
+		}
+		iaddr = page_to_virt(page) + (gpa & ~PAGE_MASK);
+		ioat->head[i] = (unsigned long *)iaddr;
+		gpa += PAGE_SIZE;
+	}
+	srcu_read_unlock(&kvm->srcu, idx);
+
+	ioat->seg = kcalloc(ZPCI_TABLE_ENTRIES_PAGES, sizeof(unsigned long *),
+			    GFP_KERNEL);
+	if (!ioat->seg)
+		goto unpin;
+	ioat->pt = kcalloc(ZPCI_TABLE_ENTRIES, sizeof(unsigned long **),
+			   GFP_KERNEL);
+	if (!ioat->pt)
+		goto free_seg;
+
+	mutex_unlock(&ioat->ioat_lock);
+	return 0;
+
+free_seg:
+	kfree(ioat->seg);
+	rc = -ENOMEM;
+unpin:
+	for (i = 0; i < ZPCI_TABLE_PAGES; i++) {
+		kvm_release_pfn_dirty((u64)ioat->head[i] >> PAGE_SHIFT);
+		ioat->head[i] = 0;
+	}
+	mutex_unlock(&ioat->ioat_lock);
+	return rc;
+}
+EXPORT_SYMBOL_GPL(kvm_s390_pci_ioat_enable);
+
+static void free_pt_entry(struct kvm_zdev_ioat *ioat, int st, int pt)
+{
+	if (!ioat->pt[st][pt])
+		return;
+
+	kvm_release_pfn_dirty((u64)ioat->pt[st][pt]);
+}
+
+static void free_seg_entry(struct kvm_zdev_ioat *ioat, int entry)
+{
+	int i, st, count = 0;
+
+	for (i = 0; i < ZPCI_TABLE_PAGES; i++) {
+		if (ioat->seg[entry + i]) {
+			kvm_release_pfn_dirty((u64)ioat->seg[entry + i]);
+			count++;
+		}
+	}
+
+	if (count == 0)
+		return;
+
+	st = entry / ZPCI_TABLE_PAGES;
+	for (i = 0; i < ZPCI_TABLE_ENTRIES; i++)
+		free_pt_entry(ioat, st, i);
+	kfree(ioat->pt[st]);
+}
+
+int kvm_s390_pci_ioat_disable(struct zpci_dev *zdev)
+{
+	struct kvm_zdev_ioat *ioat;
+	int i;
+
+	if (!shadow_ioat_init)
+		return -EINVAL;
+
+	ioat = &zdev->kzdev->ioat;
+	mutex_lock(&ioat->ioat_lock);
+	for (i = 0; i < ZPCI_TABLE_PAGES; i++) {
+		kvm_release_pfn_dirty((u64)ioat->head[i] >> PAGE_SHIFT);
+		ioat->head[i] = 0;
+	}
+
+	for (i = 0; i < ZPCI_TABLE_ENTRIES_PAGES; i += ZPCI_TABLE_PAGES)
+		free_seg_entry(ioat, i);
+
+	kfree(ioat->seg);
+	kfree(ioat->pt);
+	mutex_unlock(&ioat->ioat_lock);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(kvm_s390_pci_ioat_disable);
+
+u8 kvm_s390_pci_get_dtsm(struct zpci_dev *zdev)
+{
+	return (zdev->dtsm & KVM_S390_PCI_DTSM_MASK);
+}
+EXPORT_SYMBOL_GPL(kvm_s390_pci_get_dtsm);
+
 int kvm_s390_pci_interp_probe(struct zpci_dev *zdev)
 {
 	/* Must have appropriate hardware facilities */
@@ -449,6 +584,10 @@ int kvm_s390_pci_interp_disable(struct zpci_dev *zdev, bool force)
 	if (zdev->kzdev->fib.fmt0.aibv != 0)
 		kvm_s390_pci_aif_disable(zdev, force);
 
+	/* If we are using the IOAT assist, disable it now */
+	if (zdev->kzdev->ioat.head[0])
+		kvm_s390_pci_ioat_disable(zdev);
+
 	/* Remove the host CLP guest designation */
 	zdev->gisa = 0;
 
@@ -478,6 +617,8 @@ int kvm_s390_pci_dev_open(struct zpci_dev *zdev)
 	if (!kzdev)
 		return -ENOMEM;
 
+	mutex_init(&kzdev->ioat.ioat_lock);
+
 	kzdev->zdev = zdev;
 	zdev->kzdev = kzdev;
 
@@ -492,6 +633,7 @@ void kvm_s390_pci_dev_release(struct zpci_dev *zdev)
 	kzdev = zdev->kzdev;
 	WARN_ON(kzdev->zdev != zdev);
 	zdev->kzdev = 0;
+	mutex_destroy(&kzdev->ioat.ioat_lock);
 	kfree(kzdev);
 }
 EXPORT_SYMBOL_GPL(kvm_s390_pci_dev_release);
diff --git a/arch/s390/kvm/pci.h b/arch/s390/kvm/pci.h
index 4d3db58beb74..0fa0e3d61aaa 100644
--- a/arch/s390/kvm/pci.h
+++ b/arch/s390/kvm/pci.h
@@ -16,6 +16,8 @@
 #include <asm/airq.h>
 #include <asm/kvm_pci.h>
 
+#define KVM_S390_PCI_DTSM_MASK 0x40
+
 struct zpci_gaite {
 	u32 gisa;
 	u8 gisc;
-- 
2.27.0