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Commit b114b080 authored by Rusty Russell's avatar Rusty Russell Committed by Avi Kivity
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KVM: Use alignment properties of vcpu to simplify FPU ops 



Now we use a kmem cache for allocating vcpus, we can get the 16-byte
alignment required by fxsave & fxrstor instructions, and avoid
manually aligning the buffer.

Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
parent c16f862d

drivers/kvm/kvm.h

+4 −9
Original line number Diff line number Diff line
@@ -45,10 +45,6 @@ 
#define KVM_REFILL_PAGES 25

#define KVM_MAX_CPUID_ENTRIES 40



#define FX_IMAGE_SIZE 512

#define FX_IMAGE_ALIGN 16

#define FX_BUF_SIZE (2 * FX_IMAGE_SIZE + FX_IMAGE_ALIGN)



#define DE_VECTOR 0

#define NM_VECTOR 7

#define DF_VECTOR 8
@@ -342,9 +338,8 @@ struct kvm_vcpu { 


	struct kvm_guest_debug guest_debug;



	char fx_buf[FX_BUF_SIZE];

	char *host_fx_image;

	char *guest_fx_image;

	struct i387_fxsave_struct host_fx_image;

	struct i387_fxsave_struct guest_fx_image;

	int fpu_active;

	int guest_fpu_loaded;
@@ -704,12 +699,12 @@ static inline unsigned long read_msr(unsigned long msr) 
}

#endif



static inline void fx_save(void *image)

static inline void fx_save(struct i387_fxsave_struct *image)

{

	asm ("fxsave (%0)":: "r" (image));

}



static inline void fx_restore(void *image)

static inline void fx_restore(struct i387_fxsave_struct *image)

{

	asm ("fxrstor (%0)":: "r" (image));

}

drivers/kvm/kvm_main.c

+17 −28
Original line number Diff line number Diff line
@@ -154,8 +154,8 @@ void kvm_load_guest_fpu(struct kvm_vcpu *vcpu) 
		return;



	vcpu->guest_fpu_loaded = 1;

	fx_save(vcpu->host_fx_image);

	fx_restore(vcpu->guest_fx_image);

	fx_save(&vcpu->host_fx_image);

	fx_restore(&vcpu->guest_fx_image);

}

EXPORT_SYMBOL_GPL(kvm_load_guest_fpu);
@@ -165,8 +165,8 @@ void kvm_put_guest_fpu(struct kvm_vcpu *vcpu) 
		return;



	vcpu->guest_fpu_loaded = 0;

	fx_save(vcpu->guest_fx_image);

	fx_restore(vcpu->host_fx_image);

	fx_save(&vcpu->guest_fx_image);

	fx_restore(&vcpu->host_fx_image);

}

EXPORT_SYMBOL_GPL(kvm_put_guest_fpu);
@@ -262,10 +262,6 @@ int kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id) 
	}

	vcpu->pio_data = page_address(page);



	vcpu->host_fx_image = (char*)ALIGN((hva_t)vcpu->fx_buf,

					   FX_IMAGE_ALIGN);

	vcpu->guest_fx_image = vcpu->host_fx_image + FX_IMAGE_SIZE;



	r = kvm_mmu_create(vcpu);

	if (r < 0)

		goto fail_free_pio_data;
@@ -615,30 +611,20 @@ EXPORT_SYMBOL_GPL(set_cr8); 


void fx_init(struct kvm_vcpu *vcpu)

{

	struct __attribute__ ((__packed__)) fx_image_s {

		u16 control; //fcw

		u16 status; //fsw

		u16 tag; // ftw

		u16 opcode; //fop

		u64 ip; // fpu ip

		u64 operand;// fpu dp

		u32 mxcsr;

		u32 mxcsr_mask;



	} *fx_image;

	unsigned after_mxcsr_mask;



	/* Initialize guest FPU by resetting ours and saving into guest's */

	preempt_disable();

	fx_save(vcpu->host_fx_image);

	fx_save(&vcpu->host_fx_image);

	fpu_init();

	fx_save(vcpu->guest_fx_image);

	fx_restore(vcpu->host_fx_image);

	fx_save(&vcpu->guest_fx_image);

	fx_restore(&vcpu->host_fx_image);

	preempt_enable();



	fx_image = (struct fx_image_s *)vcpu->guest_fx_image;

	fx_image->mxcsr = 0x1f80;

	memset(vcpu->guest_fx_image + sizeof(struct fx_image_s),

	       0, FX_IMAGE_SIZE - sizeof(struct fx_image_s));

	after_mxcsr_mask = offsetof(struct i387_fxsave_struct, st_space);

	vcpu->guest_fx_image.mxcsr = 0x1f80;

	memset((void *)&vcpu->guest_fx_image + after_mxcsr_mask,

	       0, sizeof(struct i387_fxsave_struct) - after_mxcsr_mask);

}

EXPORT_SYMBOL_GPL(fx_init);
@@ -2356,6 +2342,9 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, int n) 


	preempt_notifier_init(&vcpu->preempt_notifier, &kvm_preempt_ops);



	/* We do fxsave: this must be aligned. */

	BUG_ON((unsigned long)&vcpu->host_fx_image & 0xF);



	vcpu_load(vcpu);

	r = kvm_mmu_setup(vcpu);

	vcpu_put(vcpu);
@@ -2468,7 +2457,7 @@ struct fxsave { 


static int kvm_vcpu_ioctl_get_fpu(struct kvm_vcpu *vcpu, struct kvm_fpu *fpu)

{

	struct fxsave *fxsave = (struct fxsave *)vcpu->guest_fx_image;

	struct fxsave *fxsave = (struct fxsave *)&vcpu->guest_fx_image;



	vcpu_load(vcpu);
@@ -2488,7 +2477,7 @@ static int kvm_vcpu_ioctl_get_fpu(struct kvm_vcpu *vcpu, struct kvm_fpu *fpu) 


static int kvm_vcpu_ioctl_set_fpu(struct kvm_vcpu *vcpu, struct kvm_fpu *fpu)

{

	struct fxsave *fxsave = (struct fxsave *)vcpu->guest_fx_image;

	struct fxsave *fxsave = (struct fxsave *)&vcpu->guest_fx_image;



	vcpu_load(vcpu);

drivers/kvm/svm.c

+4 −4
Original line number Diff line number Diff line
@@ -1557,8 +1557,8 @@ static int svm_vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run) 
	}



	if (vcpu->fpu_active) {

		fx_save(vcpu->host_fx_image);

		fx_restore(vcpu->guest_fx_image);

		fx_save(&vcpu->host_fx_image);

		fx_restore(&vcpu->guest_fx_image);

	}



	asm volatile (
@@ -1670,8 +1670,8 @@ static int svm_vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run) 
	vcpu->guest_mode = 0;



	if (vcpu->fpu_active) {

		fx_save(vcpu->guest_fx_image);

		fx_restore(vcpu->host_fx_image);

		fx_save(&vcpu->guest_fx_image);

		fx_restore(&vcpu->host_fx_image);

	}



	if ((svm->vmcb->save.dr7 & 0xff))