[PATCH 8/8] KVM: PPC: Book 3S: Add API for in-kernel XICS emulation

Paul Mackerras
2013-04-18T06:32:55Z

This adds the API for userspace to instantiate an XICS device in a VM
and connect VCPUs to it. The API consists of a new device type for
the KVM_CREATE_DEVICE ioctl, a new capability KVM_CAP_IRQ_XICS, which
functions similarly to KVM_CAP_IRQ_MPIC, and the KVM_IRQ_LINE ioctl,
which is used to assert and deassert interrupt inputs of the XICS.

The XICS device has one attribute group, KVM_DEV_XICS_GRP_SOURCES.
Each attribute within this group corresponds to the state of one
interrupt source. The attribute number is the same as the interrupt
source number.

Signed-off-by: Paul Mackerras <paulus@samba.org>
---
Documentation/virtual/kvm/api.txt | 8 ++
Documentation/virtual/kvm/devices/xics.txt | 66 +++++++++
arch/powerpc/include/asm/kvm_ppc.h | 2 +
arch/powerpc/include/uapi/asm/kvm.h | 12 ++
arch/powerpc/kvm/book3s_xics.c | 211 ++++++++++++++++++++++++++--
arch/powerpc/kvm/book3s_xics.h | 6 +
arch/powerpc/kvm/powerpc.c | 35 +++++
include/linux/kvm_host.h | 1 +
include/uapi/linux/kvm.h | 2 +
virt/kvm/kvm_main.c | 5 +
10 files changed, 339 insertions(+), 9 deletions(-)
create mode 100644 Documentation/virtual/kvm/devices/xics.txt

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index 54bb6ad..db230f8 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -2756,3 +2756,11 @@ Parameters: args[0] is the MPIC device fd
args[1] is the MPIC CPU number for this vcpu

This capability connects the vcpu to an in-kernel MPIC device.
+
+6.7 KVM_CAP_IRQ_XICS
+
+Architectures: ppc
+Parameters: args[0] is the XICS device fd
+ args[1] is the XICS CPU number (server ID) for this vcpu
+
+This capability connects the vcpu to an in-kernel XICS device.
diff --git a/Documentation/virtual/kvm/devices/xics.txt b/Documentation/virtual/kvm/devices/xics.txt
new file mode 100644
index 0000000..4286493
--- /dev/null
+++ b/Documentation/virtual/kvm/devices/xics.txt
@@ -0,0 +1,66 @@
+XICS interrupt controller
+
+Device type supported: KVM_DEV_TYPE_XICS
+
+Groups:
+ KVM_DEV_XICS_SOURCES
+ Attributes: One per interrupt source, indexed by the source number.
+
+This device emulates the XICS (eXternal Interrupt Controller
+Specification) defined in PAPR. The XICS has a set of interrupt
+sources, each identified by a 20-bit source number, and a set of
+Interrupt Control Presentation (ICP) entities, also called "servers",
+each associated with a virtual CPU.
+
+The ICP entities are created by enabling the KVM_CAP_IRQ_ARCH
+capability for each vcpu, specifying KVM_CAP_IRQ_XICS in args[0] and
+the interrupt server number (i.e. the vcpu number from the XICS's
+point of view) in args[1] of the kvm_enable_cap struct. Each ICP has
+64 bits of state which can be read and written using the
+KVM_GET_ONE_REG and KVM_SET_ONE_REG ioctls on the vcpu. The 64 bit
+state word has the following bitfields, starting at the
+least-significant end of the word:
+
+* Unused, 16 bits
+
+* Pending interrupt priority, 8 bits
+ Zero is the highest priority, 255 means no interrupt is pending.
+
+* Pending IPI (inter-processor interrupt) priority, 8 bits
+ Zero is the highest priority, 255 means no IPI is pending.
+
+* Pending interrupt source number, 24 bits
+ Zero means no interrupt pending, 2 means an IPI is pending
+
+* Current processor priority, 8 bits
+ Zero is the highest priority, meaning no interrupts can be
+ delivered, and 255 is the lowest priority.
+
+Each source has 64 bits of state that can be read and written using
+the KVM_GET_DEVICE_ATTR and KVM_SET_DEVICE_ATTR ioctls, specifying the
+KVM_DEV_XICS_SOURCES attribute group, with the attribute number being
+the interrupt source number. The 64 bit state word has the following
+bitfields, starting from the least-significant end of the word:
+
+* Destination (server number), 32 bits
+ This specifies where the interrupt should be sent, and is the
+ interrupt server number specified for the destination vcpu.
+
+* Priority, 8 bits
+ This is the priority specified for this interrupt source, where 0 is
+ the highest priority and 255 is the lowest. An interrupt with a
+ priority of 255 will never be delivered.
+
+* Level sensitive flag, 1 bit
+ This bit is 1 for a level-sensitive interrupt source, or 0 for
+ edge-sensitive (or MSI).
+
+* Masked flag, 1 bit
+ This bit is set to 1 if the interrupt is masked (cannot be delivered
+ regardless of its priority), for example by the ibm,int-off RTAS
+ call, or 0 if it is not masked.
+
+* Pending flag, 1 bit
+ This bit is 1 if the source has a pending interrupt, otherwise 0.
+
+Only one XICS instance may be created per VM.
diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h
index 44c8ea1..6041406 100644
--- a/arch/powerpc/include/asm/kvm_ppc.h
+++ b/arch/powerpc/include/asm/kvm_ppc.h
@@ -315,6 +315,8 @@ extern int kvm_vm_ioctl_xics_irq(struct kvm *kvm, struct kvm_irq_level *args);
extern int kvmppc_xics_hcall(struct kvm_vcpu *vcpu, u32 cmd);
extern u64 kvmppc_xics_get_icp(struct kvm_vcpu *vcpu);
extern int kvmppc_xics_set_icp(struct kvm_vcpu *vcpu, u64 icpval);
+extern int kvmppc_xics_connect_vcpu(struct kvm_device *dev,
+ struct kvm_vcpu *vcpu, u32 cpu);
#else
static inline int kvmppc_xics_enabled(struct kvm_vcpu *vcpu)
{ return 0; }
diff --git a/arch/powerpc/include/uapi/asm/kvm.h b/arch/powerpc/include/uapi/asm/kvm.h
index 1388282..ed5f6a2 100644
--- a/arch/powerpc/include/uapi/asm/kvm.h
+++ b/arch/powerpc/include/uapi/asm/kvm.h
@@ -451,4 +451,16 @@ struct kvm_get_htab_header {
#define KVM_DEV_MPIC_GRP_REGISTER 2 /* 32-bit */
#define KVM_DEV_MPIC_GRP_IRQ_ACTIVE 3 /* 32-bit */

+/* PPC64 eXternal Interrupt Controller Specification */
+#define KVM_DEV_XICS_GRP_SOURCES 1 /* 64-bit source attributes */
+
+/* Layout of 64-bit source attribute values */
+#define KVM_XICS_DESTINATION_SHIFT 0
+#define KVM_XICS_DESTINATION_MASK 0xffffffffULL
+#define KVM_XICS_PRIORITY_SHIFT 32
+#define KVM_XICS_PRIORITY_MASK 0xff
+#define KVM_XICS_LEVEL_SENSITIVE (1ULL << 40)
+#define KVM_XICS_MASKED (1ULL << 41)
+#define KVM_XICS_PENDING (1ULL << 42)
+
#endif /* __LINUX_KVM_POWERPC_H */
diff --git a/arch/powerpc/kvm/book3s_xics.c b/arch/powerpc/kvm/book3s_xics.c
index ee841ed..0189f72 100644
--- a/arch/powerpc/kvm/book3s_xics.c
+++ b/arch/powerpc/kvm/book3s_xics.c
@@ -11,6 +11,7 @@
#include <linux/kvm_host.h>
#include <linux/err.h>
#include <linux/gfp.h>
+#include <linux/anon_inodes.h>

#include <asm/uaccess.h>
#include <asm/kvm_book3s.h>
@@ -45,6 +46,34 @@
*/

/*
+ * Lifetimes
+ * ====+ *
+ * The kvm_device code takes a reference to the struct kvm, so the
+ * struct kvm will exist while the device fd is open. That implies
+ * that we can rely on the presence of the struct kvm in the device
+ * get_attr and set_attr calls. Similarly, we can rely on the presence
+ * of the struct kvm in anything called from within a vcpu KVM_RUN
+ * call, i.e. any hcall or rtas call.
+ *
+ * Vcpus take a reference to the kvm_device, which is only dropped in
+ * kvmppc_xics_free_icp, which only gets called when the vcpu struct
+ * is freed, which only happens (currently) when the kvm struct is
+ * being freed. That implies that we can rely on the presence of the
+ * kvm_device and the struct kvmppc_xics (which has the same lifetime)
+ * in any hcall or rtas call. We can also rely on the kvm->xics pointer
+ * in those circumstances, since it only gets cleared kvmppc_xics_free.
+ *
+ * The remaining case is then the kvm_vm_ioctl_xics_irq function,
+ * called from the KVM_IRQ_LINE vm ioctl. If there are no vcpus
+ * connected, it would be possible for the kvm_device and the struct
+ * kvmppc_xics to go away concurrently with kvm_vm_ioctl_xics_irq.
+ * To guard against this possibility, we use an RCU read lock in
+ * kvm_vm_ioctl_xics_irq and free the struct kvmppc_xics and associated
+ * structures with kfree_rcu().
+ */
+
+/*
* TODO
* ==
*
@@ -55,8 +84,6 @@
*
* - Make ICS lockless as well, or at least a per-interrupt lock or hashed
* locks array to improve scalability
- *
- * - ioctl's to save/restore the entire state for snapshot & migration
*/

/* -- ICS routines -- */
@@ -891,8 +918,8 @@ static void xics_debugfs_init(struct kvmppc_xics *xics)
kfree(name);
}

-struct kvmppc_ics *kvmppc_xics_create_ics(struct kvm *kvm,
- struct kvmppc_xics *xics, int irq)
+static struct kvmppc_ics *kvmppc_xics_create_ics(struct kvm *kvm,
+ struct kvmppc_xics *xics, int irq)
{
struct kvmppc_ics *ics;
int i, icsid;
@@ -1044,6 +1071,93 @@ int kvmppc_xics_set_icp(struct kvm_vcpu *vcpu, u64 icpval)
return 0;
}

+static int xics_get_source(struct kvmppc_xics *xics, long irq, u64 addr)
+{
+ int ret;
+ struct kvmppc_ics *ics;
+ struct ics_irq_state *irqp;
+ u64 __user *ubufp = (u64 __user *) addr;
+ u16 idx;
+ u64 val, prio;
+
+ ics = kvmppc_xics_find_ics(xics, irq, &idx);
+ if (!ics)
+ return -ENOENT;
+
+ irqp = &ics->irq_state[idx];
+ mutex_lock(&ics->lock);
+ ret = -ENOENT;
+ if (irqp->exists) {
+ val = irqp->server;
+ prio = irqp->priority;
+ if (prio = MASKED) {
+ val |= KVM_XICS_MASKED;
+ prio = irqp->saved_priority;
+ }
+ val |= prio << KVM_XICS_PRIORITY_SHIFT;
+ if (irqp->asserted)
+ val |= KVM_XICS_LEVEL_SENSITIVE | KVM_XICS_PENDING;
+ else if (irqp->masked_pending || irqp->resend)
+ val |= KVM_XICS_PENDING;
+ ret = 0;
+ }
+ mutex_unlock(&ics->lock);
+
+ if (!ret && put_user(val, ubufp))
+ ret = -EFAULT;
+
+ return ret;
+}
+
+static int xics_set_source(struct kvmppc_xics *xics, long irq, u64 addr)
+{
+ struct kvmppc_ics *ics;
+ struct ics_irq_state *irqp;
+ u64 __user *ubufp = (u64 __user *) addr;
+ u16 idx;
+ u64 val;
+ u8 prio;
+ u32 server;
+
+ if (irq < KVMPPC_XICS_FIRST_IRQ || irq >= KVMPPC_XICS_NR_IRQS)
+ return -ENOENT;
+
+ ics = kvmppc_xics_find_ics(xics, irq, &idx);
+ if (!ics) {
+ ics = kvmppc_xics_create_ics(xics->kvm, xics, irq);
+ if (!ics)
+ return -ENOMEM;
+ }
+ irqp = &ics->irq_state[idx];
+ if (get_user(val, ubufp))
+ return -EFAULT;
+
+ server = val & KVM_XICS_DESTINATION_MASK;
+ prio = val >> KVM_XICS_PRIORITY_SHIFT;
+ if (prio != MASKED &&
+ kvmppc_xics_find_server(xics->kvm, server) = NULL)
+ return -EINVAL;
+
+ mutex_lock(&ics->lock);
+ irqp->server = server;
+ irqp->saved_priority = prio;
+ if (val & KVM_XICS_MASKED)
+ prio = MASKED;
+ irqp->priority = prio;
+ irqp->resend = 0;
+ irqp->masked_pending = 0;
+ irqp->asserted = 0;
+ if ((val & KVM_XICS_PENDING) && (val & KVM_XICS_LEVEL_SENSITIVE))
+ irqp->asserted = 1;
+ irqp->exists = 1;
+ mutex_unlock(&ics->lock);
+
+ if (val & KVM_XICS_PENDING)
+ icp_deliver_irq(xics, NULL, irqp->number);
+
+ return 0;
+}
+
/* -- ioctls -- */

int kvm_vm_ioctl_xics_irq(struct kvm *kvm, struct kvm_irq_level *args)
@@ -1053,9 +1167,11 @@ int kvm_vm_ioctl_xics_irq(struct kvm *kvm, struct kvm_irq_level *args)

/* locking against multiple callers? */

+ rcu_read_lock();
+ r = -ENODEV;
xics = kvm->arch.xics;
if (!xics)
- return -ENODEV;
+ goto out;

switch (args->level) {
case KVM_INTERRUPT_SET:
@@ -1067,11 +1183,48 @@ int kvm_vm_ioctl_xics_irq(struct kvm *kvm, struct kvm_irq_level *args)
r = -EINVAL;
}

+ out:
+ rcu_read_unlock();
return r;
}

-void kvmppc_xics_free(struct kvmppc_xics *xics)
+static int xics_set_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
+{
+ struct kvmppc_xics *xics = dev->private;
+
+ switch (attr->group) {
+ case KVM_DEV_XICS_GRP_SOURCES:
+ return xics_set_source(xics, attr->attr, attr->addr);
+ }
+ return -ENXIO;
+}
+
+static int xics_get_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
+{
+ struct kvmppc_xics *xics = dev->private;
+
+ switch (attr->group) {
+ case KVM_DEV_XICS_GRP_SOURCES:
+ return xics_get_source(xics, attr->attr, attr->addr);
+ }
+ return -ENXIO;
+}
+
+static int xics_has_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
+{
+ switch (attr->group) {
+ case KVM_DEV_XICS_GRP_SOURCES:
+ if (attr->attr >= KVMPPC_XICS_FIRST_IRQ &&
+ attr->attr < KVMPPC_XICS_NR_IRQS)
+ return 0;
+ break;
+ }
+ return -ENXIO;
+}
+
+static void kvmppc_xics_free(struct kvm_device *dev)
{
+ struct kvmppc_xics *xics = dev->private;
int i;
struct kvm *kvm = xics->kvm;

@@ -1081,19 +1234,24 @@ void kvmppc_xics_free(struct kvmppc_xics *xics)
kvm->arch.xics = NULL;

for (i = 0; i <= xics->max_icsid; i++)
- kfree(xics->ics[i]);
- kfree(xics);
+ if (xics->ics[i])
+ kfree_rcu(xics->ics[i], rhead);
+ kfree_rcu(xics, rhead);
+ kfree(dev);
}

-int kvm_xics_create(struct kvm *kvm, u32 type)
+static int kvmppc_xics_create(struct kvm_device *dev, u32 type)
{
struct kvmppc_xics *xics;
+ struct kvm *kvm = dev->kvm;
int ret = 0;

xics = kzalloc(sizeof(*xics), GFP_KERNEL);
if (!xics)
return -ENOMEM;

+ dev->private = xics;
+ xics->dev = dev;
xics->kvm = kvm;

/* Already there ? */
@@ -1120,11 +1278,46 @@ int kvm_xics_create(struct kvm *kvm, u32 type)
return 0;
}

+struct kvm_device_ops kvm_xics_ops = {
+ .name = "kvm-xics",
+ .create = kvmppc_xics_create,
+ .destroy = kvmppc_xics_free,
+ .set_attr = xics_set_attr,
+ .get_attr = xics_get_attr,
+ .has_attr = xics_has_attr,
+};
+
+int kvmppc_xics_connect_vcpu(struct kvm_device *dev, struct kvm_vcpu *vcpu,
+ u32 xcpu)
+{
+ struct kvmppc_xics *xics = dev->private;
+ int r = -EBUSY;
+
+ if (dev->ops != &kvm_xics_ops)
+ return -EPERM;
+ if (xics->kvm != vcpu->kvm)
+ return -EPERM;
+ if (vcpu->arch.irq_type)
+ return -EBUSY;
+
+ r = kvmppc_xics_create_icp(vcpu, xcpu);
+ if (!r) {
+ vcpu->arch.irq_type = KVMPPC_IRQ_XICS;
+ kvm_device_get(xics->dev);
+ }
+
+ return r;
+}
+
void kvmppc_xics_free_icp(struct kvm_vcpu *vcpu)
{
+ struct kvmppc_xics *xics = vcpu->kvm->arch.xics;
+
if (!vcpu->arch.icp)
return;
kfree(vcpu->arch.icp);
vcpu->arch.icp = NULL;
vcpu->arch.irq_type = KVMPPC_IRQ_DEFAULT;
+ if (xics)
+ kvm_device_put(xics->dev);
}
diff --git a/arch/powerpc/kvm/book3s_xics.h b/arch/powerpc/kvm/book3s_xics.h
index e4fdec3..939074c 100644
--- a/arch/powerpc/kvm/book3s_xics.h
+++ b/arch/powerpc/kvm/book3s_xics.h
@@ -10,6 +10,9 @@
#ifndef _KVM_PPC_BOOK3S_XICS_H
#define _KVM_PPC_BOOK3S_XICS_H

+#include <linux/types.h>
+#include <linux/rcupdate.h>
+
/*
* We use a two-level tree to store interrupt source information.
* There are up to 1024 ICS nodes, each of which can represent
@@ -83,12 +86,15 @@ struct kvmppc_icp {
struct kvmppc_ics {
struct mutex lock;
u16 icsid;
+ struct rcu_head rhead;
struct ics_irq_state irq_state[KVMPPC_XICS_IRQ_PER_ICS];
};

struct kvmppc_xics {
struct kvm *kvm;
+ struct kvm_device *dev;
struct dentry *dentry;
+ struct rcu_head rhead;
u32 max_icsid;
bool real_mode;
bool real_mode_dbg;
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 2441b81..232a174 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -341,6 +341,9 @@ int kvm_dev_ioctl_check_extension(long ext)
case KVM_CAP_SPAPR_TCE:
case KVM_CAP_PPC_ALLOC_HTAB:
case KVM_CAP_PPC_RTAS:
+#ifdef CONFIG_KVM_XICS
+ case KVM_CAP_IRQ_XICS:
+#endif
r = 1;
break;
#endif /* CONFIG_PPC_BOOK3S_64 */
@@ -829,6 +832,25 @@ static int kvm_vcpu_ioctl_enable_cap(struct kvm_vcpu *vcpu,
break;
}
#endif
+#ifdef CONFIG_KVM_XICS
+ case KVM_CAP_IRQ_XICS: {
+ struct file *filp;
+ struct kvm_device *dev;
+
+ r = -EBADF;
+ filp = fget(cap->args[0]);
+ if (!filp)
+ break;
+
+ r = -EPERM;
+ dev = kvm_device_from_filp(filp);
+ if (dev)
+ r = kvmppc_xics_connect_vcpu(dev, vcpu, cap->args[1]);
+
+ fput(filp);
+ break;
+ }
+#endif /* CONFIG_KVM_XICS */
default:
r = -EINVAL;
break;
@@ -1037,6 +1059,19 @@ long kvm_arch_vm_ioctl(struct file *filp,
break;
}
#endif /* CONFIG_PPC_BOOK3S_64 */
+
+ case KVM_IRQ_LINE: {
+ struct kvm *kvm = filp->private_data;
+ struct kvm_irq_level args;
+
+ r = -EFAULT;
+ if (copy_from_user(&args, argp, sizeof(args)))
+ break;
+
+ /* Call all the interrupt controllers */
+ r = kvm_vm_ioctl_xics_irq(kvm, &args);
+ break;
+ }
default:
r = -ENOTTY;
}
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 55d3d9c..adfb42c 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1102,6 +1102,7 @@ void kvm_device_put(struct kvm_device *dev);
struct kvm_device *kvm_device_from_filp(struct file *filp);

extern struct kvm_device_ops kvm_mpic_ops;
+extern struct kvm_device_ops kvm_xics_ops;

#ifdef CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT

diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index d100ac6..7189175 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -671,6 +671,7 @@ struct kvm_ppc_smmu_info {
#define KVM_CAP_DEVICE_CTRL 89
#define KVM_CAP_IRQ_MPIC 90
#define KVM_CAP_PPC_RTAS 91
+#define KVM_CAP_IRQ_XICS 92

#ifdef KVM_CAP_IRQ_ROUTING

@@ -933,6 +934,7 @@ struct kvm_device_attr {

#define KVM_DEV_TYPE_FSL_MPIC_20 1
#define KVM_DEV_TYPE_FSL_MPIC_42 2
+#define KVM_DEV_TYPE_XICS 3

/* ioctl for vm fd */
#define KVM_CREATE_DEVICE _IOWR(KVMIO, 0xe0, struct kvm_create_device)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 5a51869..3ba2076 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2244,6 +2244,11 @@ static int kvm_ioctl_create_device(struct kvm *kvm,
ops = &kvm_mpic_ops;
break;
#endif
+#ifdef CONFIG_KVM_XICS
+ case KVM_DEV_TYPE_XICS:
+ ops = &kvm_xics_ops;
+ break;
+#endif
default:
return -ENODEV;
}
--
1.7.10.4