Commit efe5ddca authored by Greg Kurz's avatar Greg Kurz Committed by Paul Mackerras
Browse files

KVM: PPC: Book3S HV: XIVE: Allow userspace to set the # of VPs 



Add a new attribute to both XIVE and XICS-on-XIVE KVM devices so that
userspace can tell how many interrupt servers it needs. If a VM needs
less than the current default of KVM_MAX_VCPUS (2048), we can allocate
less VPs in OPAL. Combined with a core stride (VSMT) that matches the
number of guest threads per core, this may substantially increases the
number of VMs that can run concurrently with an in-kernel XIVE device.

Since the legacy XIVE KVM device is exposed to userspace through the
XICS KVM API, a new attribute group is added to it for this purpose.
While here, fix the syntax of the existing KVM_DEV_XICS_GRP_SOURCES
in the XICS documentation.

Signed-off-by: default avatarGreg Kurz <groug@kaod.org>
Reviewed-by: default avatarCédric Le Goater <clg@kaod.org>
Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
parent 062cfab7

Documentation/virt/kvm/devices/xics.txt

+12 −2
Original line number Diff line number Diff line
@@ -3,9 +3,19 @@ XICS interrupt controller 
Device type supported: KVM_DEV_TYPE_XICS



Groups:

  KVM_DEV_XICS_SOURCES

  1. KVM_DEV_XICS_GRP_SOURCES

  Attributes: One per interrupt source, indexed by the source number.



  2. KVM_DEV_XICS_GRP_CTRL

  Attributes:

    2.1 KVM_DEV_XICS_NR_SERVERS (write only)

  The kvm_device_attr.addr points to a __u32 value which is the number of

  interrupt server numbers (ie, highest possible vcpu id plus one).

  Errors:

    -EINVAL: Value greater than KVM_MAX_VCPU_ID.

    -EFAULT: Invalid user pointer for attr->addr.

    -EBUSY:  A vcpu is already connected to the device.



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
@@ -38,7 +48,7 @@ least-significant end of the word: 


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

KVM_DEV_XICS_GRP_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:

Documentation/virt/kvm/devices/xive.txt

+8 −0
Original line number Diff line number Diff line
@@ -78,6 +78,14 @@ the legacy interrupt mode, referred as XICS (POWER7/8). 
    migrating the VM.

    Errors: none



    1.3 KVM_DEV_XIVE_NR_SERVERS (write only)

    The kvm_device_attr.addr points to a __u32 value which is the number of

    interrupt server numbers (ie, highest possible vcpu id plus one).

    Errors:

      -EINVAL: Value greater than KVM_MAX_VCPU_ID.

      -EFAULT: Invalid user pointer for attr->addr.

      -EBUSY:  A vCPU is already connected to the device.



  2. KVM_DEV_XIVE_GRP_SOURCE (write only)

  Initializes a new source in the XIVE device and mask it.

  Attributes:

arch/powerpc/include/uapi/asm/kvm.h

+3 −0
Original line number Diff line number Diff line
@@ -667,6 +667,8 @@ struct kvm_ppc_cpu_char { 


/* PPC64 eXternal Interrupt Controller Specification */

#define KVM_DEV_XICS_GRP_SOURCES	1	/* 64-bit source attributes */

#define KVM_DEV_XICS_GRP_CTRL		2

#define   KVM_DEV_XICS_NR_SERVERS	1



/* Layout of 64-bit source attribute values */

#define  KVM_XICS_DESTINATION_SHIFT	0
@@ -683,6 +685,7 @@ struct kvm_ppc_cpu_char { 
#define KVM_DEV_XIVE_GRP_CTRL		1

#define   KVM_DEV_XIVE_RESET		1

#define   KVM_DEV_XIVE_EQ_SYNC		2

#define   KVM_DEV_XIVE_NR_SERVERS	3

#define KVM_DEV_XIVE_GRP_SOURCE		2	/* 64-bit source identifier */

#define KVM_DEV_XIVE_GRP_SOURCE_CONFIG	3	/* 64-bit source identifier */

#define KVM_DEV_XIVE_GRP_EQ_CONFIG	4	/* 64-bit EQ identifier */

arch/powerpc/kvm/book3s_xive.c

+10 −0
Original line number Diff line number Diff line
@@ -1911,6 +1911,11 @@ static int xive_set_attr(struct kvm_device *dev, struct kvm_device_attr *attr) 
	switch (attr->group) {

	case KVM_DEV_XICS_GRP_SOURCES:

		return xive_set_source(xive, attr->attr, attr->addr);

	case KVM_DEV_XICS_GRP_CTRL:

		switch (attr->attr) {

		case KVM_DEV_XICS_NR_SERVERS:

			return kvmppc_xive_set_nr_servers(xive, attr->addr);

		}

	}

	return -ENXIO;

}
@@ -1936,6 +1941,11 @@ static int xive_has_attr(struct kvm_device *dev, struct kvm_device_attr *attr) 
		    attr->attr < KVMPPC_XICS_NR_IRQS)

			return 0;

		break;

	case KVM_DEV_XICS_GRP_CTRL:

		switch (attr->attr) {

		case KVM_DEV_XICS_NR_SERVERS:

			return 0;

		}

	}

	return -ENXIO;

}

arch/powerpc/kvm/book3s_xive_native.c

+3 −0
Original line number Diff line number Diff line
@@ -921,6 +921,8 @@ static int kvmppc_xive_native_set_attr(struct kvm_device *dev, 
			return kvmppc_xive_reset(xive);

		case KVM_DEV_XIVE_EQ_SYNC:

			return kvmppc_xive_native_eq_sync(xive);

		case KVM_DEV_XIVE_NR_SERVERS:

			return kvmppc_xive_set_nr_servers(xive, attr->addr);

		}

		break;

	case KVM_DEV_XIVE_GRP_SOURCE:
@@ -960,6 +962,7 @@ static int kvmppc_xive_native_has_attr(struct kvm_device *dev, 
		switch (attr->attr) {

		case KVM_DEV_XIVE_RESET:

		case KVM_DEV_XIVE_EQ_SYNC:

		case KVM_DEV_XIVE_NR_SERVERS:

			return 0;

		}

		break;

CRA Git | Maintained and supported by SUSTech CRA and CCSE