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linux/arch/powerpc/kvm/powerpc.c
Paul Mackerras 371fefd6f2 KVM: PPC: Allow book3s_hv guests to use SMT processor modes 
This lifts the restriction that book3s_hv guests can only run one
hardware thread per core, and allows them to use up to 4 threads
per core on POWER7.  The host still has to run single-threaded.

This capability is advertised to qemu through a new KVM_CAP_PPC_SMT
capability.  The return value of the ioctl querying this capability
is the number of vcpus per virtual CPU core (vcore), currently 4.

To use this, the host kernel should be booted with all threads
active, and then all the secondary threads should be offlined.
This will put the secondary threads into nap mode.  KVM will then
wake them from nap mode and use them for running guest code (while
they are still offline).  To wake the secondary threads, we send
them an IPI using a new xics_wake_cpu() function, implemented in
arch/powerpc/sysdev/xics/icp-native.c.  In other words, at this stage
we assume that the platform has a XICS interrupt controller and
we are using icp-native.c to drive it.  Since the woken thread will
need to acknowledge and clear the IPI, we also export the base
physical address of the XICS registers using kvmppc_set_xics_phys()
for use in the low-level KVM book3s code.

When a vcpu is created, it is assigned to a virtual CPU core.
The vcore number is obtained by dividing the vcpu number by the
number of threads per core in the host.  This number is exported
to userspace via the KVM_CAP_PPC_SMT capability.  If qemu wishes
to run the guest in single-threaded mode, it should make all vcpu
numbers be multiples of the number of threads per core.

We distinguish three states of a vcpu: runnable (i.e., ready to execute
the guest), blocked (that is, idle), and busy in host.  We currently
implement a policy that the vcore can run only when all its threads
are runnable or blocked.  This way, if a vcpu needs to execute elsewhere
in the kernel or in qemu, it can do so without being starved of CPU
by the other vcpus.

When a vcore starts to run, it executes in the context of one of the
vcpu threads.  The other vcpu threads all go to sleep and stay asleep
until something happens requiring the vcpu thread to return to qemu,
or to wake up to run the vcore (this can happen when another vcpu
thread goes from busy in host state to blocked).

It can happen that a vcpu goes from blocked to runnable state (e.g.
because of an interrupt), and the vcore it belongs to is already
running.  In that case it can start to run immediately as long as
the none of the vcpus in the vcore have started to exit the guest.
We send the next free thread in the vcore an IPI to get it to start
to execute the guest.  It synchronizes with the other threads via
the vcore->entry_exit_count field to make sure that it doesn't go
into the guest if the other vcpus are exiting by the time that it
is ready to actually enter the guest.

Note that there is no fixed relationship between the hardware thread
number and the vcpu number.  Hardware threads are assigned to vcpus
as they become runnable, so we will always use the lower-numbered
hardware threads in preference to higher-numbered threads if not all
the vcpus in the vcore are runnable, regardless of which vcpus are
runnable.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
2011-07-12 13:16:57 +03:00

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/*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License, version 2, as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* Copyright IBM Corp. 2007
*
* Authors: Hollis Blanchard <hollisb@us.ibm.com>
* Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
*/
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/kvm_host.h>
#include <linux/module.h>
#include <linux/vmalloc.h>
#include <linux/hrtimer.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <asm/cputable.h>
#include <asm/uaccess.h>
#include <asm/kvm_ppc.h>
#include <asm/tlbflush.h>
#include <asm/cputhreads.h>
#include "timing.h"
#include "../mm/mmu_decl.h"
#define CREATE_TRACE_POINTS
#include "trace.h"
int kvm_arch_vcpu_runnable(struct kvm_vcpu *v)
{
#ifndef CONFIG_KVM_BOOK3S_64_HV
return !(v->arch.shared->msr & MSR_WE) ||
!!(v->arch.pending_exceptions);
#else
return !(v->arch.ceded) || !!(v->arch.pending_exceptions);
#endif
}
int kvmppc_kvm_pv(struct kvm_vcpu *vcpu)
{
int nr = kvmppc_get_gpr(vcpu, 11);
int r;
unsigned long __maybe_unused param1 = kvmppc_get_gpr(vcpu, 3);
unsigned long __maybe_unused param2 = kvmppc_get_gpr(vcpu, 4);
unsigned long __maybe_unused param3 = kvmppc_get_gpr(vcpu, 5);
unsigned long __maybe_unused param4 = kvmppc_get_gpr(vcpu, 6);
unsigned long r2 = 0;
if (!(vcpu->arch.shared->msr & MSR_SF)) {
/* 32 bit mode */
param1 &= 0xffffffff;
param2 &= 0xffffffff;
param3 &= 0xffffffff;
param4 &= 0xffffffff;
}
switch (nr) {
case HC_VENDOR_KVM | KVM_HC_PPC_MAP_MAGIC_PAGE:
{
vcpu->arch.magic_page_pa = param1;
vcpu->arch.magic_page_ea = param2;
r2 = KVM_MAGIC_FEAT_SR;
r = HC_EV_SUCCESS;
break;
}
case HC_VENDOR_KVM | KVM_HC_FEATURES:
r = HC_EV_SUCCESS;
#if defined(CONFIG_PPC_BOOK3S) || defined(CONFIG_KVM_E500)
/* XXX Missing magic page on 44x */
r2 |= (1 << KVM_FEATURE_MAGIC_PAGE);
#endif
/* Second return value is in r4 */
break;
default:
r = HC_EV_UNIMPLEMENTED;
break;
}
kvmppc_set_gpr(vcpu, 4, r2);
return r;
}
int kvmppc_emulate_mmio(struct kvm_run *run, struct kvm_vcpu *vcpu)
{
enum emulation_result er;
int r;
er = kvmppc_emulate_instruction(run, vcpu);
switch (er) {
case EMULATE_DONE:
/* Future optimization: only reload non-volatiles if they were
* actually modified. */
r = RESUME_GUEST_NV;
break;
case EMULATE_DO_MMIO:
run->exit_reason = KVM_EXIT_MMIO;
/* We must reload nonvolatiles because "update" load/store
* instructions modify register state. */
/* Future optimization: only reload non-volatiles if they were
* actually modified. */
r = RESUME_HOST_NV;
break;
case EMULATE_FAIL:
/* XXX Deliver Program interrupt to guest. */
printk(KERN_EMERG "%s: emulation failed (%08x)\n", __func__,
kvmppc_get_last_inst(vcpu));
r = RESUME_HOST;
break;
default:
BUG();
}
return r;
}
int kvm_arch_hardware_enable(void *garbage)
{
return 0;
}
void kvm_arch_hardware_disable(void *garbage)
{
}
int kvm_arch_hardware_setup(void)
{
return 0;
}
void kvm_arch_hardware_unsetup(void)
{
}
void kvm_arch_check_processor_compat(void *rtn)
{
*(int *)rtn = kvmppc_core_check_processor_compat();
}
int kvm_arch_init_vm(struct kvm *kvm)
{
return kvmppc_core_init_vm(kvm);
}
void kvm_arch_destroy_vm(struct kvm *kvm)
{
unsigned int i;
struct kvm_vcpu *vcpu;
kvm_for_each_vcpu(i, vcpu, kvm)
kvm_arch_vcpu_free(vcpu);
mutex_lock(&kvm->lock);
for (i = 0; i < atomic_read(&kvm->online_vcpus); i++)
kvm->vcpus[i] = NULL;
atomic_set(&kvm->online_vcpus, 0);
kvmppc_core_destroy_vm(kvm);
mutex_unlock(&kvm->lock);
}
void kvm_arch_sync_events(struct kvm *kvm)
{
}
int kvm_dev_ioctl_check_extension(long ext)
{
int r;
switch (ext) {
#ifdef CONFIG_BOOKE
case KVM_CAP_PPC_BOOKE_SREGS:
#else
case KVM_CAP_PPC_SEGSTATE:
#endif
case KVM_CAP_PPC_UNSET_IRQ:
case KVM_CAP_PPC_IRQ_LEVEL:
case KVM_CAP_ENABLE_CAP:
r = 1;
break;
#ifndef CONFIG_KVM_BOOK3S_64_HV
case KVM_CAP_PPC_PAIRED_SINGLES:
case KVM_CAP_PPC_OSI:
case KVM_CAP_PPC_GET_PVINFO:
r = 1;
break;
case KVM_CAP_COALESCED_MMIO:
r = KVM_COALESCED_MMIO_PAGE_OFFSET;
break;
#endif
#ifdef CONFIG_KVM_BOOK3S_64_HV
case KVM_CAP_SPAPR_TCE:
r = 1;
break;
case KVM_CAP_PPC_SMT:
r = threads_per_core;
break;
#endif
default:
r = 0;
break;
}
return r;
}
long kvm_arch_dev_ioctl(struct file *filp,
unsigned int ioctl, unsigned long arg)
{
return -EINVAL;
}
int kvm_arch_prepare_memory_region(struct kvm *kvm,
struct kvm_memory_slot *memslot,
struct kvm_memory_slot old,
struct kvm_userspace_memory_region *mem,
int user_alloc)
{
return kvmppc_core_prepare_memory_region(kvm, mem);
}
void kvm_arch_commit_memory_region(struct kvm *kvm,
struct kvm_userspace_memory_region *mem,
struct kvm_memory_slot old,
int user_alloc)
{
kvmppc_core_commit_memory_region(kvm, mem);
}
void kvm_arch_flush_shadow(struct kvm *kvm)
{
}
struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm, unsigned int id)
{
struct kvm_vcpu *vcpu;
vcpu = kvmppc_core_vcpu_create(kvm, id);
if (!IS_ERR(vcpu))
kvmppc_create_vcpu_debugfs(vcpu, id);
return vcpu;
}
void kvm_arch_vcpu_free(struct kvm_vcpu *vcpu)
{
/* Make sure we're not using the vcpu anymore */
hrtimer_cancel(&vcpu->arch.dec_timer);
tasklet_kill(&vcpu->arch.tasklet);
kvmppc_remove_vcpu_debugfs(vcpu);
kvmppc_core_vcpu_free(vcpu);
}
void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
{
kvm_arch_vcpu_free(vcpu);
}
int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu)
{
return kvmppc_core_pending_dec(vcpu);
}
static void kvmppc_decrementer_func(unsigned long data)
{
struct kvm_vcpu *vcpu = (struct kvm_vcpu *)data;
kvmppc_core_queue_dec(vcpu);
if (waitqueue_active(&vcpu->wq)) {
wake_up_interruptible(&vcpu->wq);
vcpu->stat.halt_wakeup++;
}
}
/*
* low level hrtimer wake routine. Because this runs in hardirq context
* we schedule a tasklet to do the real work.
*/
enum hrtimer_restart kvmppc_decrementer_wakeup(struct hrtimer *timer)
{
struct kvm_vcpu *vcpu;
vcpu = container_of(timer, struct kvm_vcpu, arch.dec_timer);
tasklet_schedule(&vcpu->arch.tasklet);
return HRTIMER_NORESTART;
}
int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
{
hrtimer_init(&vcpu->arch.dec_timer, CLOCK_REALTIME, HRTIMER_MODE_ABS);
tasklet_init(&vcpu->arch.tasklet, kvmppc_decrementer_func, (ulong)vcpu);
vcpu->arch.dec_timer.function = kvmppc_decrementer_wakeup;
vcpu->arch.dec_expires = ~(u64)0;
#ifdef CONFIG_KVM_EXIT_TIMING
mutex_init(&vcpu->arch.exit_timing_lock);
#endif
return 0;
}
void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu)
{
kvmppc_mmu_destroy(vcpu);
}
void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
{
#ifdef CONFIG_BOOKE
/*
* vrsave (formerly usprg0) isn't used by Linux, but may
* be used by the guest.
*
* On non-booke this is associated with Altivec and
* is handled by code in book3s.c.
*/
mtspr(SPRN_VRSAVE, vcpu->arch.vrsave);
#endif
kvmppc_core_vcpu_load(vcpu, cpu);
vcpu->cpu = smp_processor_id();
}
void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
{
kvmppc_core_vcpu_put(vcpu);
#ifdef CONFIG_BOOKE
vcpu->arch.vrsave = mfspr(SPRN_VRSAVE);
#endif
vcpu->cpu = -1;
}
int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
struct kvm_guest_debug *dbg)
{
return -EINVAL;
}
static void kvmppc_complete_dcr_load(struct kvm_vcpu *vcpu,
struct kvm_run *run)
{
kvmppc_set_gpr(vcpu, vcpu->arch.io_gpr, run->dcr.data);
}
static void kvmppc_complete_mmio_load(struct kvm_vcpu *vcpu,
struct kvm_run *run)
{
u64 uninitialized_var(gpr);
if (run->mmio.len > sizeof(gpr)) {
printk(KERN_ERR "bad MMIO length: %d\n", run->mmio.len);
return;
}
if (vcpu->arch.mmio_is_bigendian) {
switch (run->mmio.len) {
case 8: gpr = *(u64 *)run->mmio.data; break;
case 4: gpr = *(u32 *)run->mmio.data; break;
case 2: gpr = *(u16 *)run->mmio.data; break;
case 1: gpr = *(u8 *)run->mmio.data; break;
}
} else {
/* Convert BE data from userland back to LE. */
switch (run->mmio.len) {
case 4: gpr = ld_le32((u32 *)run->mmio.data); break;
case 2: gpr = ld_le16((u16 *)run->mmio.data); break;
case 1: gpr = *(u8 *)run->mmio.data; break;
}
}
if (vcpu->arch.mmio_sign_extend) {
switch (run->mmio.len) {
#ifdef CONFIG_PPC64
case 4:
gpr = (s64)(s32)gpr;
break;
#endif
case 2:
gpr = (s64)(s16)gpr;
break;
case 1:
gpr = (s64)(s8)gpr;
break;
}
}
kvmppc_set_gpr(vcpu, vcpu->arch.io_gpr, gpr);
switch (vcpu->arch.io_gpr & KVM_REG_EXT_MASK) {
case KVM_REG_GPR:
kvmppc_set_gpr(vcpu, vcpu->arch.io_gpr, gpr);
break;
case KVM_REG_FPR:
vcpu->arch.fpr[vcpu->arch.io_gpr & KVM_REG_MASK] = gpr;
break;
#ifdef CONFIG_PPC_BOOK3S
case KVM_REG_QPR:
vcpu->arch.qpr[vcpu->arch.io_gpr & KVM_REG_MASK] = gpr;
break;
case KVM_REG_FQPR:
vcpu->arch.fpr[vcpu->arch.io_gpr & KVM_REG_MASK] = gpr;
vcpu->arch.qpr[vcpu->arch.io_gpr & KVM_REG_MASK] = gpr;
break;
#endif
default:
BUG();
}
}
int kvmppc_handle_load(struct kvm_run *run, struct kvm_vcpu *vcpu,
unsigned int rt, unsigned int bytes, int is_bigendian)
{
if (bytes > sizeof(run->mmio.data)) {
printk(KERN_ERR "%s: bad MMIO length: %d\n", __func__,
run->mmio.len);
}
run->mmio.phys_addr = vcpu->arch.paddr_accessed;
run->mmio.len = bytes;
run->mmio.is_write = 0;
vcpu->arch.io_gpr = rt;
vcpu->arch.mmio_is_bigendian = is_bigendian;
vcpu->mmio_needed = 1;
vcpu->mmio_is_write = 0;
vcpu->arch.mmio_sign_extend = 0;
return EMULATE_DO_MMIO;
}
/* Same as above, but sign extends */
int kvmppc_handle_loads(struct kvm_run *run, struct kvm_vcpu *vcpu,
unsigned int rt, unsigned int bytes, int is_bigendian)
{
int r;
r = kvmppc_handle_load(run, vcpu, rt, bytes, is_bigendian);
vcpu->arch.mmio_sign_extend = 1;
return r;
}
int kvmppc_handle_store(struct kvm_run *run, struct kvm_vcpu *vcpu,
u64 val, unsigned int bytes, int is_bigendian)
{
void *data = run->mmio.data;
if (bytes > sizeof(run->mmio.data)) {
printk(KERN_ERR "%s: bad MMIO length: %d\n", __func__,
run->mmio.len);
}
run->mmio.phys_addr = vcpu->arch.paddr_accessed;
run->mmio.len = bytes;
run->mmio.is_write = 1;
vcpu->mmio_needed = 1;
vcpu->mmio_is_write = 1;
/* Store the value at the lowest bytes in 'data'. */
if (is_bigendian) {
switch (bytes) {
case 8: *(u64 *)data = val; break;
case 4: *(u32 *)data = val; break;
case 2: *(u16 *)data = val; break;
case 1: *(u8 *)data = val; break;
}
} else {
/* Store LE value into 'data'. */
switch (bytes) {
case 4: st_le32(data, val); break;
case 2: st_le16(data, val); break;
case 1: *(u8 *)data = val; break;
}
}
return EMULATE_DO_MMIO;
}
int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
{
int r;
sigset_t sigsaved;
if (vcpu->sigset_active)
sigprocmask(SIG_SETMASK, &vcpu->sigset, &sigsaved);
if (vcpu->mmio_needed) {
if (!vcpu->mmio_is_write)
kvmppc_complete_mmio_load(vcpu, run);
vcpu->mmio_needed = 0;
} else if (vcpu->arch.dcr_needed) {
if (!vcpu->arch.dcr_is_write)
kvmppc_complete_dcr_load(vcpu, run);
vcpu->arch.dcr_needed = 0;
} else if (vcpu->arch.osi_needed) {
u64 *gprs = run->osi.gprs;
int i;
for (i = 0; i < 32; i++)
kvmppc_set_gpr(vcpu, i, gprs[i]);
vcpu->arch.osi_needed = 0;
} else if (vcpu->arch.hcall_needed) {
int i;
kvmppc_set_gpr(vcpu, 3, run->papr_hcall.ret);
for (i = 0; i < 9; ++i)
kvmppc_set_gpr(vcpu, 4 + i, run->papr_hcall.args[i]);
vcpu->arch.hcall_needed = 0;
}
kvmppc_core_deliver_interrupts(vcpu);
r = kvmppc_vcpu_run(run, vcpu);
if (vcpu->sigset_active)
sigprocmask(SIG_SETMASK, &sigsaved, NULL);
return r;
}
int kvm_vcpu_ioctl_interrupt(struct kvm_vcpu *vcpu, struct kvm_interrupt *irq)
{
if (irq->irq == KVM_INTERRUPT_UNSET)
kvmppc_core_dequeue_external(vcpu, irq);
else
kvmppc_core_queue_external(vcpu, irq);
if (waitqueue_active(&vcpu->wq)) {
wake_up_interruptible(&vcpu->wq);
vcpu->stat.halt_wakeup++;
} else if (vcpu->cpu != -1) {
smp_send_reschedule(vcpu->cpu);
}
return 0;
}
static int kvm_vcpu_ioctl_enable_cap(struct kvm_vcpu *vcpu,
struct kvm_enable_cap *cap)
{
int r;
if (cap->flags)
return -EINVAL;
switch (cap->cap) {
case KVM_CAP_PPC_OSI:
r = 0;
vcpu->arch.osi_enabled = true;
break;
default:
r = -EINVAL;
break;
}
return r;
}
int kvm_arch_vcpu_ioctl_get_mpstate(struct kvm_vcpu *vcpu,
struct kvm_mp_state *mp_state)
{
return -EINVAL;
}
int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu,
struct kvm_mp_state *mp_state)
{
return -EINVAL;
}
long kvm_arch_vcpu_ioctl(struct file *filp,
unsigned int ioctl, unsigned long arg)
{
struct kvm_vcpu *vcpu = filp->private_data;
void __user *argp = (void __user *)arg;
long r;
switch (ioctl) {
case KVM_INTERRUPT: {
struct kvm_interrupt irq;
r = -EFAULT;
if (copy_from_user(&irq, argp, sizeof(irq)))
goto out;
r = kvm_vcpu_ioctl_interrupt(vcpu, &irq);
goto out;
}
case KVM_ENABLE_CAP:
{
struct kvm_enable_cap cap;
r = -EFAULT;
if (copy_from_user(&cap, argp, sizeof(cap)))
goto out;
r = kvm_vcpu_ioctl_enable_cap(vcpu, &cap);
break;
}
default:
r = -EINVAL;
}
out:
return r;
}
static int kvm_vm_ioctl_get_pvinfo(struct kvm_ppc_pvinfo *pvinfo)
{
u32 inst_lis = 0x3c000000;
u32 inst_ori = 0x60000000;
u32 inst_nop = 0x60000000;
u32 inst_sc = 0x44000002;
u32 inst_imm_mask = 0xffff;
/*
* The hypercall to get into KVM from within guest context is as
* follows:
*
* lis r0, r0, KVM_SC_MAGIC_R0@h
* ori r0, KVM_SC_MAGIC_R0@l
* sc
* nop
*/
pvinfo->hcall[0] = inst_lis | ((KVM_SC_MAGIC_R0 >> 16) & inst_imm_mask);
pvinfo->hcall[1] = inst_ori | (KVM_SC_MAGIC_R0 & inst_imm_mask);
pvinfo->hcall[2] = inst_sc;
pvinfo->hcall[3] = inst_nop;
return 0;
}
long kvm_arch_vm_ioctl(struct file *filp,
unsigned int ioctl, unsigned long arg)
{
void __user *argp = (void __user *)arg;
long r;
switch (ioctl) {
case KVM_PPC_GET_PVINFO: {
struct kvm_ppc_pvinfo pvinfo;
memset(&pvinfo, 0, sizeof(pvinfo));
r = kvm_vm_ioctl_get_pvinfo(&pvinfo);
if (copy_to_user(argp, &pvinfo, sizeof(pvinfo))) {
r = -EFAULT;
goto out;
}
break;
}
#ifdef CONFIG_KVM_BOOK3S_64_HV
case KVM_CREATE_SPAPR_TCE: {
struct kvm_create_spapr_tce create_tce;
struct kvm *kvm = filp->private_data;
r = -EFAULT;
if (copy_from_user(&create_tce, argp, sizeof(create_tce)))
goto out;
r = kvm_vm_ioctl_create_spapr_tce(kvm, &create_tce);
goto out;
}
#endif /* CONFIG_KVM_BOOK3S_64_HV */
default:
r = -ENOTTY;
}
out:
return r;
}
int kvm_arch_init(void *opaque)
{
return 0;
}
void kvm_arch_exit(void)
{
}
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