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Commit 8fae845f authored by Scott Wood's avatar Scott Wood Committed by Avi Kivity
Browse files

KVM: PPC: booke: standard PPC floating point support 



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: default avatarScott Wood <scottwood@freescale.com>
Signed-off-by: default avatarAlexander Graf <agraf@suse.de>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent d30f6e48

arch/powerpc/include/asm/switch_to.h

+1 −0
Original line number Diff line number Diff line
@@ -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 *);

arch/powerpc/kvm/booke.c

+44 −0
Original line number Diff line number Diff line
@@ -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:

arch/powerpc/kvm/booke.h

+31 −0
Original line number Diff line number Diff line
@@ -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__ */