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KVM: PPC: booke: standard PPC floating point support

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e500mc has a normal PPC FPU, rather than SPE which is found
on e500v1/v2.

Based on code from Liu Yu <yu.liu@freescale.com>.

Signed-off-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Scott Wood 2011-12-20 15:34:45 +00:00 committed by Avi Kivity
parent d30f6e4800
commit 8fae845f49
3 changed files with 76 additions and 0 deletions
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1
arch/powerpc/include/asm/switch_to.h
View file

@ -17,6 +17,7 @@ extern struct task_struct *_switch(struct thread_struct *prev,
struct thread_struct *next);
extern void giveup_fpu(struct task_struct *);
extern void load_up_fpu(void);
extern void disable_kernel_fp(void);
extern void enable_kernel_fp(void);
extern void flush_fp_to_thread(struct task_struct *);

44
arch/powerpc/kvm/booke.c
View file

@ -457,6 +457,11 @@ void kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu)
int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
{
int ret;
#ifdef CONFIG_PPC_FPU
unsigned int fpscr;
int fpexc_mode;
u64 fpr[32];
#endif
if (!vcpu->arch.sane) {
kvm_run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
@ -479,7 +484,46 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
}
kvm_guest_enter();
#ifdef CONFIG_PPC_FPU
/* Save userspace FPU state in stack */
enable_kernel_fp();
memcpy(fpr, current->thread.fpr, sizeof(current->thread.fpr));
fpscr = current->thread.fpscr.val;
fpexc_mode = current->thread.fpexc_mode;
/* Restore guest FPU state to thread */
memcpy(current->thread.fpr, vcpu->arch.fpr, sizeof(vcpu->arch.fpr));
current->thread.fpscr.val = vcpu->arch.fpscr;
/*
* Since we can't trap on MSR_FP in GS-mode, we consider the guest
* as always using the FPU. Kernel usage of FP (via
* enable_kernel_fp()) in this thread must not occur while
* vcpu->fpu_active is set.
*/
vcpu->fpu_active = 1;
kvmppc_load_guest_fp(vcpu);
#endif
ret = __kvmppc_vcpu_run(kvm_run, vcpu);
#ifdef CONFIG_PPC_FPU
kvmppc_save_guest_fp(vcpu);
vcpu->fpu_active = 0;
/* Save guest FPU state from thread */
memcpy(vcpu->arch.fpr, current->thread.fpr, sizeof(vcpu->arch.fpr));
vcpu->arch.fpscr = current->thread.fpscr.val;
/* Restore userspace FPU state from stack */
memcpy(current->thread.fpr, fpr, sizeof(current->thread.fpr));
current->thread.fpscr.val = fpscr;
current->thread.fpexc_mode = fpexc_mode;
#endif
kvm_guest_exit();
out:

31
arch/powerpc/kvm/booke.h
View file

@ -23,6 +23,7 @@
#include <linux/types.h>
#include <linux/kvm_host.h>
#include <asm/kvm_ppc.h>
#include <asm/switch_to.h>
#include "timing.h"
/* interrupt priortity ordering */
@ -96,4 +97,34 @@ enum int_class {
void kvmppc_set_pending_interrupt(struct kvm_vcpu *vcpu, enum int_class type);
/*
* Load up guest vcpu FP state if it's needed.
* It also set the MSR_FP in thread so that host know
* we're holding FPU, and then host can help to save
* guest vcpu FP state if other threads require to use FPU.
* This simulates an FP unavailable fault.
*
* It requires to be called with preemption disabled.
*/
static inline void kvmppc_load_guest_fp(struct kvm_vcpu *vcpu)
{
#ifdef CONFIG_PPC_FPU
if (vcpu->fpu_active && !(current->thread.regs->msr & MSR_FP)) {
load_up_fpu();
current->thread.regs->msr |= MSR_FP;
}
#endif
}
/*
* Save guest vcpu FP state into thread.
* It requires to be called with preemption disabled.
*/
static inline void kvmppc_save_guest_fp(struct kvm_vcpu *vcpu)
{
#ifdef CONFIG_PPC_FPU
if (vcpu->fpu_active && (current->thread.regs->msr & MSR_FP))
giveup_fpu(current);
#endif
}
#endif /* __KVM_BOOKE_H__ */