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: Greg Kurz <groug@kaod.org>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

diff --git a/Documentation/virt/kvm/devices/xics.txt b/Documentation/virt/kvm/devices/xics.txt
index 42864935ac5d174d508bd9dc47b0ad6579d740d3..423332dda7bc893104a4e12d3b71b482ea590c19 100644 (file)
--- a/Documentation/virt/kvm/devices/xics.txt
+++ b/Documentation/virt/kvm/devices/xics.txt
@@ -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:
 

diff --git a/Documentation/virt/kvm/devices/xive.txt b/Documentation/virt/kvm/devices/xive.txt
index 9a24a45252539d7f693e77afb737cd0c5bcab511..f5d1d6b5af61504dd501192e61c71d6333ceb83a 100644 (file)
--- a/Documentation/virt/kvm/devices/xive.txt
+++ b/Documentation/virt/kvm/devices/xive.txt
@@ -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:

diff --git a/arch/powerpc/include/uapi/asm/kvm.h b/arch/powerpc/include/uapi/asm/kvm.h
index b0f72dea8b11ac689c990971dbf78c1601ef4e7a..264e266a85bf6a99c5b27b47733ad5f11b5e02d5 100644 (file)
--- a/arch/powerpc/include/uapi/asm/kvm.h
+++ b/arch/powerpc/include/uapi/asm/kvm.h
@@ -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 */

diff --git a/arch/powerpc/kvm/book3s_xive.c b/arch/powerpc/kvm/book3s_xive.c
index 6c35b3d9598687922416d3366fcebf1f4a87755f..66858b7d3c6b4d120ecf9412ecf75d69a62c8411 100644 (file)
--- a/arch/powerpc/kvm/book3s_xive.c
+++ b/arch/powerpc/kvm/book3s_xive.c
@@ -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;
 }

diff --git a/arch/powerpc/kvm/book3s_xive_native.c b/arch/powerpc/kvm/book3s_xive_native.c
index 8ab333eabeef51d039f4ba0e935d583d5e3001e3..34bd123fa0241c3ededa444d42833d67ffcc3cf6 100644 (file)
--- a/arch/powerpc/kvm/book3s_xive_native.c
+++ b/arch/powerpc/kvm/book3s_xive_native.c
@@ -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;