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linux/arch/powerpc/include/asm/kvm_ppc.h
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. 2008
*
* Authors: Hollis Blanchard <hollisb@us.ibm.com>
*/
#ifndef __POWERPC_KVM_PPC_H__
#define __POWERPC_KVM_PPC_H__
/* This file exists just so we can dereference kvm_vcpu, avoiding nested header
* dependencies. */
#include <linux/mutex.h>
#include <linux/timer.h>
#include <linux/types.h>
#include <linux/kvm_types.h>
#include <linux/kvm_host.h>
#ifdef CONFIG_PPC_BOOK3S
#include <asm/kvm_book3s.h>
#else
#include <asm/kvm_booke.h>
#endif
#ifdef CONFIG_KVM_BOOK3S_64_HANDLER
#include <asm/paca.h>
#endif
enum emulation_result {
EMULATE_DONE, /* no further processing */
EMULATE_DO_MMIO, /* kvm_run filled with MMIO request */
EMULATE_DO_DCR, /* kvm_run filled with DCR request */
EMULATE_FAIL, /* can't emulate this instruction */
EMULATE_AGAIN, /* something went wrong. go again */
};
extern int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu);
extern int __kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu);
extern char kvmppc_handlers_start[];
extern unsigned long kvmppc_handler_len;
extern void kvmppc_handler_highmem(void);
extern void kvmppc_dump_vcpu(struct kvm_vcpu *vcpu);
extern int kvmppc_handle_load(struct kvm_run *run, struct kvm_vcpu *vcpu,
unsigned int rt, unsigned int bytes,
int is_bigendian);
extern int kvmppc_handle_loads(struct kvm_run *run, struct kvm_vcpu *vcpu,
unsigned int rt, unsigned int bytes,
int is_bigendian);
extern int kvmppc_handle_store(struct kvm_run *run, struct kvm_vcpu *vcpu,
u64 val, unsigned int bytes, int is_bigendian);
extern int kvmppc_emulate_instruction(struct kvm_run *run,
struct kvm_vcpu *vcpu);
extern int kvmppc_emulate_mmio(struct kvm_run *run, struct kvm_vcpu *vcpu);
extern void kvmppc_emulate_dec(struct kvm_vcpu *vcpu);
extern u32 kvmppc_get_dec(struct kvm_vcpu *vcpu, u64 tb);
/* Core-specific hooks */
extern void kvmppc_mmu_map(struct kvm_vcpu *vcpu, u64 gvaddr, gpa_t gpaddr,
unsigned int gtlb_idx);
extern void kvmppc_mmu_priv_switch(struct kvm_vcpu *vcpu, int usermode);
extern void kvmppc_mmu_switch_pid(struct kvm_vcpu *vcpu, u32 pid);
extern void kvmppc_mmu_destroy(struct kvm_vcpu *vcpu);
extern int kvmppc_mmu_init(struct kvm_vcpu *vcpu);
extern int kvmppc_mmu_dtlb_index(struct kvm_vcpu *vcpu, gva_t eaddr);
extern int kvmppc_mmu_itlb_index(struct kvm_vcpu *vcpu, gva_t eaddr);
extern gpa_t kvmppc_mmu_xlate(struct kvm_vcpu *vcpu, unsigned int gtlb_index,
gva_t eaddr);
extern void kvmppc_mmu_dtlb_miss(struct kvm_vcpu *vcpu);
extern void kvmppc_mmu_itlb_miss(struct kvm_vcpu *vcpu);
extern struct kvm_vcpu *kvmppc_core_vcpu_create(struct kvm *kvm,
unsigned int id);
extern void kvmppc_core_vcpu_free(struct kvm_vcpu *vcpu);
extern int kvmppc_core_vcpu_setup(struct kvm_vcpu *vcpu);
extern int kvmppc_core_check_processor_compat(void);
extern int kvmppc_core_vcpu_translate(struct kvm_vcpu *vcpu,
struct kvm_translation *tr);
extern void kvmppc_core_vcpu_load(struct kvm_vcpu *vcpu, int cpu);
extern void kvmppc_core_vcpu_put(struct kvm_vcpu *vcpu);
extern void kvmppc_core_deliver_interrupts(struct kvm_vcpu *vcpu);
extern int kvmppc_core_pending_dec(struct kvm_vcpu *vcpu);
extern void kvmppc_core_queue_program(struct kvm_vcpu *vcpu, ulong flags);
extern void kvmppc_core_queue_dec(struct kvm_vcpu *vcpu);
extern void kvmppc_core_dequeue_dec(struct kvm_vcpu *vcpu);
extern void kvmppc_core_queue_external(struct kvm_vcpu *vcpu,
struct kvm_interrupt *irq);
extern void kvmppc_core_dequeue_external(struct kvm_vcpu *vcpu,
struct kvm_interrupt *irq);
extern int kvmppc_core_emulate_op(struct kvm_run *run, struct kvm_vcpu *vcpu,
unsigned int op, int *advance);
extern int kvmppc_core_emulate_mtspr(struct kvm_vcpu *vcpu, int sprn, int rs);
extern int kvmppc_core_emulate_mfspr(struct kvm_vcpu *vcpu, int sprn, int rt);
extern int kvmppc_booke_init(void);
extern void kvmppc_booke_exit(void);
extern void kvmppc_core_destroy_mmu(struct kvm_vcpu *vcpu);
extern int kvmppc_kvm_pv(struct kvm_vcpu *vcpu);
extern void kvmppc_map_magic(struct kvm_vcpu *vcpu);
extern long kvmppc_alloc_hpt(struct kvm *kvm);
extern void kvmppc_free_hpt(struct kvm *kvm);
extern long kvmppc_prepare_vrma(struct kvm *kvm,
struct kvm_userspace_memory_region *mem);
extern void kvmppc_map_vrma(struct kvm *kvm,
struct kvm_userspace_memory_region *mem);
extern int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu);
extern long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm,
struct kvm_create_spapr_tce *args);
extern int kvmppc_core_init_vm(struct kvm *kvm);
extern void kvmppc_core_destroy_vm(struct kvm *kvm);
extern int kvmppc_core_prepare_memory_region(struct kvm *kvm,
struct kvm_userspace_memory_region *mem);
extern void kvmppc_core_commit_memory_region(struct kvm *kvm,
struct kvm_userspace_memory_region *mem);
/*
* Cuts out inst bits with ordering according to spec.
* That means the leftmost bit is zero. All given bits are included.
*/
static inline u32 kvmppc_get_field(u64 inst, int msb, int lsb)
{
u32 r;
u32 mask;
BUG_ON(msb > lsb);
mask = (1 << (lsb - msb + 1)) - 1;
r = (inst >> (63 - lsb)) & mask;
return r;
}
/*
* Replaces inst bits with ordering according to spec.
*/
static inline u32 kvmppc_set_field(u64 inst, int msb, int lsb, int value)
{
u32 r;
u32 mask;
BUG_ON(msb > lsb);
mask = ((1 << (lsb - msb + 1)) - 1) << (63 - lsb);
r = (inst & ~mask) | ((value << (63 - lsb)) & mask);
return r;
}
void kvmppc_core_get_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs);
int kvmppc_core_set_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs);
void kvmppc_get_sregs_ivor(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs);
int kvmppc_set_sregs_ivor(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs);
void kvmppc_set_pid(struct kvm_vcpu *vcpu, u32 pid);
#ifdef CONFIG_KVM_BOOK3S_64_HV
static inline void kvmppc_set_xics_phys(int cpu, unsigned long addr)
{
paca[cpu].kvm_hstate.xics_phys = addr;
}
#else
static inline void kvmppc_set_xics_phys(int cpu, unsigned long addr)
{}
#endif
#endif /* __POWERPC_KVM_PPC_H__ */
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