> -----Original Message----- > From: Avi Kivity [mailto:avi@xxxxxxxxxx] > Sent: Wednesday, September 05, 2012 9:13 PM > To: Hao, Xudong > Cc: kvm@xxxxxxxxxxxxxxx; Zhang, Xiantao; Joerg.Roedel@xxxxxxx > Subject: Re: [PATCH v2] kvm/fpu: Enable fully eager restore kvm FPU > > On 09/05/2012 04:26 AM, Xudong Hao wrote: > > Enable KVM FPU fully eager restore, if there is other FPU state which isn't > > tracked by CR0.TS bit. > > > > Changes from v1: > > Expand KVM_XSTATE_LAZY to 64 bits before negating it. > > > > Signed-off-by: Xudong Hao <xudong.hao@xxxxxxxxx> > > --- > > arch/x86/include/asm/kvm.h | 4 ++++ > > arch/x86/kvm/x86.c | 13 ++++++++++++- > > 2 files changed, 16 insertions(+), 1 deletions(-) > > > > diff --git a/arch/x86/include/asm/kvm.h b/arch/x86/include/asm/kvm.h > > index 521bf25..4c27056 100644 > > --- a/arch/x86/include/asm/kvm.h > > +++ b/arch/x86/include/asm/kvm.h > > @@ -8,6 +8,8 @@ > > > > #include <linux/types.h> > > #include <linux/ioctl.h> > > +#include <asm/user.h> > > +#include <asm/xsave.h> > > > > /* Select x86 specific features in <linux/kvm.h> */ > > #define __KVM_HAVE_PIT > > @@ -30,6 +32,8 @@ > > /* Architectural interrupt line count. */ > > #define KVM_NR_INTERRUPTS 256 > > > > +#define KVM_XSTATE_LAZY (XSTATE_FP | XSTATE_SSE | XSTATE_YMM) > > + > > struct kvm_memory_alias { > > __u32 slot; /* this has a different namespace than memory slots */ > > __u32 flags; > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > > index 20f2266..a632042 100644 > > --- a/arch/x86/kvm/x86.c > > +++ b/arch/x86/kvm/x86.c > > @@ -5969,7 +5969,18 @@ void kvm_put_guest_fpu(struct kvm_vcpu *vcpu) > > vcpu->guest_fpu_loaded = 0; > > fpu_save_init(&vcpu->arch.guest_fpu); > > ++vcpu->stat.fpu_reload; > > - kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu); > > + /* > > + * Currently KVM trigger FPU restore by #NM (via CR0.TS), > > + * till now only XCR0.bit0, XCR0.bit1, XCR0.bit2 is tracked > > + * by TS bit, there might be other FPU state is not tracked > > + * by TS bit. Here it only make FPU deactivate request and do > > + * FPU lazy restore for these cases: 1)xsave isn't enabled > > + * in guest, 2)all guest FPU states can be tracked by TS bit. > > + * For others, doing fully FPU eager restore. > > + */ > > + if (!kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE) || > > + !(vcpu->arch.xcr0 & ~((u64)KVM_XSTATE_LAZY))) > > + kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu); > > trace_kvm_fpu(0); > > } > > > > I think something is missing. This patch prevents > KVM_REQ_DEACTIVATE_FPU, but the fpu may not be active when non-lazy bits > are added to xcr0 (or cr4.osxsave is enabled). I think you need to > activate the fpu at that time as well. > Mmh, I thought fpu is active by default, but it's better to make fpu active explicitly here. If the following patch is fine, I'll make it another version. - kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu); + if (kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE) && + (vcpu->arch.xcr0 & ~((u64)KVM_XSTATE_LAZY))) + kvm_x86_ops->fpu_activate(vcpu); + else + kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu); Thanks, -Xudong -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
