[PATCH][v2 2/3] KVM: x86: Use unlazy_fpu() for host FPU
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From: Sheng Yang on 17 May 2010 05:20 We can avoid unnecessary fpu load when userspace process didn't use FPU frequently. Derived from Avi's idea. Signed-off-by: Sheng Yang <sheng(a)linux.intel.com> --- arch/x86/include/asm/kvm_host.h | 1 - arch/x86/kvm/x86.c | 18 ++---------------- 2 files changed, 2 insertions(+), 17 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 0c06148..d93601c 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -301,7 +301,6 @@ struct kvm_vcpu_arch { unsigned long mmu_seq; } update_pte; - struct i387_fxsave_struct host_fx_image; struct i387_fxsave_struct guest_fx_image; gva_t mmio_fault_cr2; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 7500cba..ba8c2d2 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -52,6 +52,7 @@ #include <asm/desc.h> #include <asm/mtrr.h> #include <asm/mce.h> +#include <asm/i387.h> #define MAX_IO_MSRS 256 #define CR0_RESERVED_BITS \ @@ -5134,21 +5135,10 @@ void fx_init(struct kvm_vcpu *vcpu) { unsigned after_mxcsr_mask; - /* - * Touch the fpu the first time in non atomic context as if - * this is the first fpu instruction the exception handler - * will fire before the instruction returns and it'll have to - * allocate ram with GFP_KERNEL. - */ - if (!used_math()) - kvm_fx_save(&vcpu->arch.host_fx_image); - /* Initialize guest FPU by resetting ours and saving into guest's */ preempt_disable(); - kvm_fx_save(&vcpu->arch.host_fx_image); kvm_fx_finit(); kvm_fx_save(&vcpu->arch.guest_fx_image); - kvm_fx_restore(&vcpu->arch.host_fx_image); preempt_enable(); vcpu->arch.cr0 |= X86_CR0_ET; @@ -5165,7 +5155,7 @@ void kvm_load_guest_fpu(struct kvm_vcpu *vcpu) return; vcpu->guest_fpu_loaded = 1; - kvm_fx_save(&vcpu->arch.host_fx_image); + unlazy_fpu(current); kvm_fx_restore(&vcpu->arch.guest_fx_image); trace_kvm_fpu(1); } @@ -5177,7 +5167,6 @@ void kvm_put_guest_fpu(struct kvm_vcpu *vcpu) vcpu->guest_fpu_loaded = 0; kvm_fx_save(&vcpu->arch.guest_fx_image); - kvm_fx_restore(&vcpu->arch.host_fx_image); ++vcpu->stat.fpu_reload; set_bit(KVM_REQ_DEACTIVATE_FPU, &vcpu->requests); trace_kvm_fpu(0); @@ -5203,9 +5192,6 @@ int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu) { int r; - /* We do fxsave: this must be aligned. */ - BUG_ON((unsigned long)&vcpu->arch.host_fx_image & 0xF); - vcpu->arch.mtrr_state.have_fixed = 1; vcpu_load(vcpu); r = kvm_arch_vcpu_reset(vcpu); -- 1.7.0.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |