From b114b0804df7131cb6764b948c1c530c834fa3c0 Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Mon, 30 Jul 2007 21:13:43 +1000 Subject: [PATCH] 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: Rusty Russell Signed-off-by: Avi Kivity --- drivers/kvm/kvm.h | 13 ++++--------- drivers/kvm/kvm_main.c | 45 +++++++++++++++++---------------------------- drivers/kvm/svm.c | 8 ++++---- 3 files changed, 25 insertions(+), 41 deletions(-) diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h index b362e8f..7a34706 100644 --- a/drivers/kvm/kvm.h +++ b/drivers/kvm/kvm.h @@ -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)); } diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c index 4166a08..bfb1b6d 100644 --- a/drivers/kvm/kvm_main.c +++ b/drivers/kvm/kvm_main.c @@ -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); diff --git a/drivers/kvm/svm.c b/drivers/kvm/svm.c index 8193651..5277084 100644 --- a/drivers/kvm/svm.c +++ b/drivers/kvm/svm.c @@ -1557,8 +1557,8 @@ again: } 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 @@ again: 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)) -- 2.7.4