[PATCH v4 2/6] powerpc/kvm/xive: Enable use of the new "single escalation" feature
Benjamin Herrenschmidt
benh at kernel.crashing.org
Fri Jan 12 13:37:12 AEDT 2018
That feature, provided by Power9 DDD2.0 and later, when supported
by newer OPAL versions, allows to sacrifice a queue (priority 7)
in favor of merging all the escalation interrupts of the queues
of a single VP into a single interrupt.
This reduces the number of host interrupts used up by KVM guests
especially when those guests use multiple priorities.
It will also enable a future change to control the masking of the
escalation interrupts more precisely to avoid spurrious ones.
Signed-off-by: Benjamin Herrenschmidt <benh at kernel.crashing.org>
---
arch/powerpc/include/asm/opal-api.h | 1 +
arch/powerpc/include/asm/xive.h | 3 ++-
arch/powerpc/kvm/book3s_xive.c | 48 ++++++++++++++++++++++++-------------
arch/powerpc/kvm/book3s_xive.h | 15 +++++-------
arch/powerpc/sysdev/xive/native.c | 18 ++++++++++++--
5 files changed, 57 insertions(+), 28 deletions(-)
diff --git a/arch/powerpc/include/asm/opal-api.h b/arch/powerpc/include/asm/opal-api.h
index 233c7504b1f2..fc926743647e 100644
--- a/arch/powerpc/include/asm/opal-api.h
+++ b/arch/powerpc/include/asm/opal-api.h
@@ -1073,6 +1073,7 @@ enum {
/* Flags for OPAL_XIVE_GET/SET_VP_INFO */
enum {
OPAL_XIVE_VP_ENABLED = 0x00000001,
+ OPAL_XIVE_VP_SINGLE_ESCALATION = 0x00000002,
};
/* "Any chip" replacement for chip ID for allocation functions */
diff --git a/arch/powerpc/include/asm/xive.h b/arch/powerpc/include/asm/xive.h
index b619a5585cd6..e602903c3029 100644
--- a/arch/powerpc/include/asm/xive.h
+++ b/arch/powerpc/include/asm/xive.h
@@ -111,9 +111,10 @@ extern void xive_native_disable_queue(u32 vp_id, struct xive_q *q, u8 prio);
extern void xive_native_sync_source(u32 hw_irq);
extern bool is_xive_irq(struct irq_chip *chip);
-extern int xive_native_enable_vp(u32 vp_id);
+extern int xive_native_enable_vp(u32 vp_id, bool single_escalation);
extern int xive_native_disable_vp(u32 vp_id);
extern int xive_native_get_vp_info(u32 vp_id, u32 *out_cam_id, u32 *out_chip_id);
+extern bool xive_native_has_single_escalation(void);
#else
diff --git a/arch/powerpc/kvm/book3s_xive.c b/arch/powerpc/kvm/book3s_xive.c
index cd21c891be9e..87f814e81e7d 100644
--- a/arch/powerpc/kvm/book3s_xive.c
+++ b/arch/powerpc/kvm/book3s_xive.c
@@ -112,19 +112,21 @@ static int xive_attach_escalation(struct kvm_vcpu *vcpu, u8 prio)
return -EIO;
}
- /*
- * Future improvement: start with them disabled
- * and handle DD2 and later scheme of merged escalation
- * interrupts
- */
- name = kasprintf(GFP_KERNEL, "kvm-%d-%d-%d",
- vcpu->kvm->arch.lpid, xc->server_num, prio);
+ if (xc->xive->single_escalation)
+ name = kasprintf(GFP_KERNEL, "kvm-%d-%d",
+ vcpu->kvm->arch.lpid, xc->server_num);
+ else
+ name = kasprintf(GFP_KERNEL, "kvm-%d-%d-%d",
+ vcpu->kvm->arch.lpid, xc->server_num, prio);
if (!name) {
pr_err("Failed to allocate escalation irq name for queue %d of VCPU %d\n",
prio, xc->server_num);
rc = -ENOMEM;
goto error;
}
+
+ pr_devel("Escalation %s irq %d (prio %d)\n", name, xc->esc_virq[prio], prio);
+
rc = request_irq(xc->esc_virq[prio], xive_esc_irq,
IRQF_NO_THREAD, name, vcpu);
if (rc) {
@@ -191,12 +193,12 @@ static int xive_check_provisioning(struct kvm *kvm, u8 prio)
pr_devel("Provisioning prio... %d\n", prio);
- /* Provision each VCPU and enable escalations */
+ /* Provision each VCPU and enable escalations if needed */
kvm_for_each_vcpu(i, vcpu, kvm) {
if (!vcpu->arch.xive_vcpu)
continue;
rc = xive_provision_queue(vcpu, prio);
- if (rc == 0)
+ if (rc == 0 && !xive->single_escalation)
xive_attach_escalation(vcpu, prio);
if (rc)
return rc;
@@ -1082,6 +1084,7 @@ int kvmppc_xive_connect_vcpu(struct kvm_device *dev,
/* Allocate IPI */
xc->vp_ipi = xive_native_alloc_irq();
if (!xc->vp_ipi) {
+ pr_err("Failed to allocate xive irq for VCPU IPI\n");
r = -EIO;
goto bail;
}
@@ -1091,19 +1094,34 @@ int kvmppc_xive_connect_vcpu(struct kvm_device *dev,
if (r)
goto bail;
+ /*
+ * Enable the VP first as the single escalation mode will
+ * affect escalation interrupts numbering
+ */
+ r = xive_native_enable_vp(xc->vp_id, xive->single_escalation);
+ if (r) {
+ pr_err("Failed to enable VP in OPAL, err %d\n", r);
+ goto bail;
+ }
+
/*
* Initialize queues. Initially we set them all for no queueing
* and we enable escalation for queue 0 only which we'll use for
* our mfrr change notifications. If the VCPU is hot-plugged, we
- * do handle provisioning however.
+ * do handle provisioning however based on the existing "map"
+ * of enabled queues.
*/
for (i = 0; i < KVMPPC_XIVE_Q_COUNT; i++) {
struct xive_q *q = &xc->queues[i];
+ /* Single escalation, no queue 7 */
+ if (i == 7 && xive->single_escalation)
+ break;
+
/* Is queue already enabled ? Provision it */
if (xive->qmap & (1 << i)) {
r = xive_provision_queue(vcpu, i);
- if (r == 0)
+ if (r == 0 && !xive->single_escalation)
xive_attach_escalation(vcpu, i);
if (r)
goto bail;
@@ -1123,11 +1141,6 @@ int kvmppc_xive_connect_vcpu(struct kvm_device *dev,
if (r)
goto bail;
- /* Enable the VP */
- r = xive_native_enable_vp(xc->vp_id);
- if (r)
- goto bail;
-
/* Route the IPI */
r = xive_native_configure_irq(xc->vp_ipi, xc->vp_id, 0, XICS_IPI);
if (!r)
@@ -1474,6 +1487,7 @@ static int xive_set_source(struct kvmppc_xive *xive, long irq, u64 addr)
pr_devel(" val=0x016%llx (server=0x%x, guest_prio=%d)\n",
val, server, guest_prio);
+
/*
* If the source doesn't already have an IPI, allocate
* one and get the corresponding data
@@ -1762,6 +1776,8 @@ static int kvmppc_xive_create(struct kvm_device *dev, u32 type)
if (xive->vp_base == XIVE_INVALID_VP)
ret = -ENOMEM;
+ xive->single_escalation = xive_native_has_single_escalation();
+
if (ret) {
kfree(xive);
return ret;
diff --git a/arch/powerpc/kvm/book3s_xive.h b/arch/powerpc/kvm/book3s_xive.h
index 6ba63f8e8a61..a08ae6fd4c51 100644
--- a/arch/powerpc/kvm/book3s_xive.h
+++ b/arch/powerpc/kvm/book3s_xive.h
@@ -120,6 +120,8 @@ struct kvmppc_xive {
u32 q_order;
u32 q_page_order;
+ /* Flags */
+ u8 single_escalation;
};
#define KVMPPC_XIVE_Q_COUNT 8
@@ -201,25 +203,20 @@ static inline struct kvmppc_xive_src_block *kvmppc_xive_find_source(struct kvmpp
* is as follow.
*
* Guest request for 0...6 are honored. Guest request for anything
- * higher results in a priority of 7 being applied.
- *
- * However, when XIRR is returned via H_XIRR, 7 is translated to 0xb
- * in order to match AIX expectations
+ * higher results in a priority of 6 being applied.
*
* Similar mapping is done for CPPR values
*/
static inline u8 xive_prio_from_guest(u8 prio)
{
- if (prio == 0xff || prio < 8)
+ if (prio == 0xff || prio < 6)
return prio;
- return 7;
+ return 6;
}
static inline u8 xive_prio_to_guest(u8 prio)
{
- if (prio == 0xff || prio < 7)
- return prio;
- return 0xb;
+ return prio;
}
static inline u32 __xive_read_eq(__be32 *qpage, u32 msk, u32 *idx, u32 *toggle)
diff --git a/arch/powerpc/sysdev/xive/native.c b/arch/powerpc/sysdev/xive/native.c
index ebc244b08d67..d22aeb0b69e1 100644
--- a/arch/powerpc/sysdev/xive/native.c
+++ b/arch/powerpc/sysdev/xive/native.c
@@ -42,6 +42,7 @@ static u32 xive_provision_chip_count;
static u32 xive_queue_shift;
static u32 xive_pool_vps = XIVE_INVALID_VP;
static struct kmem_cache *xive_provision_cache;
+static bool xive_has_single_esc;
int xive_native_populate_irq_data(u32 hw_irq, struct xive_irq_data *data)
{
@@ -571,6 +572,10 @@ bool __init xive_native_init(void)
break;
}
+ /* Do we support single escalation */
+ if (of_get_property(np, "single-escalation-support", NULL) != NULL)
+ xive_has_single_esc = true;
+
/* Configure Thread Management areas for KVM */
for_each_possible_cpu(cpu)
kvmppc_set_xive_tima(cpu, r.start, tima);
@@ -667,12 +672,15 @@ void xive_native_free_vp_block(u32 vp_base)
}
EXPORT_SYMBOL_GPL(xive_native_free_vp_block);
-int xive_native_enable_vp(u32 vp_id)
+int xive_native_enable_vp(u32 vp_id, bool single_escalation)
{
s64 rc;
+ u64 flags = OPAL_XIVE_VP_ENABLED;
+ if (single_escalation)
+ flags |= OPAL_XIVE_VP_SINGLE_ESCALATION;
for (;;) {
- rc = opal_xive_set_vp_info(vp_id, OPAL_XIVE_VP_ENABLED, 0);
+ rc = opal_xive_set_vp_info(vp_id, flags, 0);
if (rc != OPAL_BUSY)
break;
msleep(1);
@@ -710,3 +718,9 @@ int xive_native_get_vp_info(u32 vp_id, u32 *out_cam_id, u32 *out_chip_id)
return 0;
}
EXPORT_SYMBOL_GPL(xive_native_get_vp_info);
+
+bool xive_native_has_single_escalation(void)
+{
+ return xive_has_single_esc;
+}
+EXPORT_SYMBOL_GPL(xive_native_has_single_escalation);
--
2.14.3
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