From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: [PATCH 2/4] Fix FPU interface changes Date: Wed, 26 May 2010 09:33:49 +0200 Message-ID: <4BFCCEDD.7090802@web.de> References: <4BFC96DE.7040702@redhat.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enigAF80A24CF7EF62AC0C4E1B3F" Cc: kvm , Avi Kivity , Gleb Natapov To: Zachary Amsden Return-path: Received: from fmmailgate01.web.de ([217.72.192.221]:39642 "EHLO fmmailgate01.web.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932536Ab0EZHdu (ORCPT ); Wed, 26 May 2010 03:33:50 -0400 In-Reply-To: <4BFC96DE.7040702@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigAF80A24CF7EF62AC0C4E1B3F Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Zachary Amsden wrote: > The FPU interface changed to dynamic allocation; redefine the missing > struct fpu to be a static structure and add back the old macros. >=20 > The FPU interface changed to dynamic allocation; redefine the missing s= truct fpu to be a static structure and add back the old macros. >=20 >=20 >=20 > From 95be2b1ac41a40f2f3d581f0674b25ca4b70a025 Mon Sep 17 00:00:00 2001 > From: Zachary Amsden > Date: Tue, 25 May 2010 16:32:14 -1000 > Subject: [PATCH 2/5] Extend module compatability to FPU code >=20 > Signed-off-by: Zachary Amsden > --- > x86/external-module-compat.h | 84 ++++++++++++++++++++++++++++++++++= ++++++++ > 1 files changed, 84 insertions(+), 0 deletions(-) >=20 > diff --git a/x86/external-module-compat.h b/x86/external-module-compat.= h > index 09bf232..316f7ff 100644 > --- a/x86/external-module-compat.h > +++ b/x86/external-module-compat.h > @@ -788,3 +788,87 @@ struct kvm_pvclock_vcpu_time_info { > #else > #define kvm_pvclock_vcpu_time_info pvclock_vcpu_time_info > #endif > + > +#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,34) The FPU changes look like 2.6.36 material. > +#include > +#include > +struct _fpu { > + struct i387_fxsave_struct fxsave; > + struct i387_fxsave_struct host_fx_image; The original code before 9144b51caf only used a single state - for the guest. > +}; > + > +struct fpu { > + struct _fpu *state; > + struct _fpu state_static; > +}; > + > +static inline bool fpu_allocated(struct fpu *fpu) > +{ > + fpu->state =3D &fpu->state_static; > + return true; > +} Unused. > + > +static inline int fpu_alloc(struct fpu *fpu) > +{ > + fpu->state =3D &fpu->state_static; > + return 0; > +} That's smarter than the dumb copy of upstream fpu_alloc that I hacked up.= > + > +static inline void fpu_free(struct fpu *fpu) > +{ > +} > + > +static inline void kvm_fx_finit(void) > +{ > + asm("finit"); > +} > + > +static inline void kvm_fx_save(struct i387_fxsave_struct *image) > +{ > + asm("fxsave (%0)":: "r" (image)); > +} > + > +static inline void kvm_fx_restore(struct i387_fxsave_struct *image) > +{ > + asm("fxrstor (%0)":: "r" (image)); > +} > + > +static inline void fpu_finit(struct fpu *fpu) > +{ > + 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(&fpu->state->host_fx_image); > + > + /* Initialize guest FPU by resetting ours and saving into guest's */ > + preempt_disable(); > + kvm_fx_save(&fpu->state->host_fx_image); > + kvm_fx_finit(); > + kvm_fx_save(&fpu->state->fxsave); > + kvm_fx_restore(&fpu->state->host_fx_image); > + preempt_enable(); The original KVM code before 9144b51caf just did finit+fxsave. Why this saving/restoring of the host state? > + > + after_mxcsr_mask =3D offsetof(struct i387_fxsave_struct, st_space); > + fpu->state->fxsave.mxcsr =3D 0x1f80; > + memset((void *)&fpu->state->fxsave + after_mxcsr_mask, > + 0, sizeof(struct i387_fxsave_struct) - after_mxcsr_mask); > +} > + > +static inline void fpu_restore_checking(struct fpu *fpu) > +{ > + kvm_fx_save(&fpu->state->host_fx_image); > + kvm_fx_restore(&fpu->state->fxsave); > +} > + > +static inline void fpu_save_init(struct fpu *fpu) > +{ > + kvm_fx_save(&fpu->state->fxsave); > + kvm_fx_restore(&fpu->state->host_fx_image); > +} Also here: Why bother about the host state? Jan --------------enigAF80A24CF7EF62AC0C4E1B3F Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.9 (GNU/Linux) Comment: Using GnuPG with SUSE - http://enigmail.mozdev.org iEYEARECAAYFAkv8zt0ACgkQitSsb3rl5xSb+wCdHCiyqqcEt6oUGT9LlsO0Ag4Y FPsAoKZl/VWDac07deEX0Jfu5e350Oiz =JUhi -----END PGP SIGNATURE----- --------------enigAF80A24CF7EF62AC0C4E1B3F--