Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935645AbcJ0ARv convert rfc822-to-8bit (ORCPT ); Wed, 26 Oct 2016 20:17:51 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48764 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933145AbcJ0ARt (ORCPT ); Wed, 26 Oct 2016 20:17:49 -0400 From: Bandan Das To: Radim =?utf-8?B?S3LEjW3DocWZ?= Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Paolo Bonzini , Laszlo Ersek Subject: Re: [PATCH 1/2] KVM: x86: emulate fxsave and fxrstor References: <20161026205014.19801-1-rkrcmar@redhat.com> <20161026205014.19801-2-rkrcmar@redhat.com> Date: Wed, 26 Oct 2016 20:17:46 -0400 In-Reply-To: <20161026205014.19801-2-rkrcmar@redhat.com> ("Radim \=\?utf-8\?B\?S3LEjW3DocWZIidz\?\= message of "Wed, 26 Oct 2016 22:50:13 +0200") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Thu, 27 Oct 2016 00:17:48 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2885 Lines: 107 Hi Radim, Radim Krčmář writes: ... > static __always_inline int __linearize(struct x86_emulate_ctxt *ctxt, > @@ -704,7 +708,7 @@ static __always_inline int __linearize(struct x86_emulate_ctxt *ctxt, > } > break; > } > - if (insn_aligned(ctxt, size) && ((la & (size - 1)) != 0)) > + if (la & (insn_alignment(ctxt, size) - 1)) > return emulate_gp(ctxt, 0); > return X86EMUL_CONTINUE; > bad: > @@ -3856,6 +3860,75 @@ static int em_movsxd(struct x86_emulate_ctxt *ctxt) > return X86EMUL_CONTINUE; > } > > +static int check_fxsr(struct x86_emulate_ctxt *ctxt) > +{ > + u32 eax = 1, ebx, ecx = 0, edx; > + > + ctxt->ops->get_cpuid(ctxt, &eax, &ebx, &ecx, &edx); > + if (!(edx & FFL(FXSR))) > + return emulate_ud(ctxt); > + > + if (ctxt->ops->get_cr(ctxt, 0) & (X86_CR0_TS | X86_CR0_EM)) > + return emulate_nm(ctxt); > + > + return X86EMUL_CONTINUE; > +} > + > +/* > + * FXSAVE and FXRSTOR have 3 different formats depending on execution mode, > + * 1) non-64-bit mode > + * 2) 64-bit mode with REX.W prefix > + * 3) 64-bit mode without REX.W prefix > + * > + * Emulation uses (3) for for (1) mode because only the number of XMM registers > + * is different. > + */ > +static int em_fxsave(struct x86_emulate_ctxt *ctxt) > +{ > + char fx_state[512] __aligned(16); > + int rc; > + > + rc = check_fxsr(ctxt); > + if (rc != X86EMUL_CONTINUE) > + return rc; > + > + ctxt->ops->get_fpu(ctxt); > +#ifdef CONFIG_X86_64 > + if (ctxt->rex_prefix & (1 << 3)) > + asm volatile("fxsave64 %0" : "+m"(fx_state)); > + else > +#endif > + asm volatile("fxsave %0" : "+m"(fx_state)); > + ctxt->ops->put_fpu(ctxt); > + > + return segmented_write(ctxt, ctxt->memop.addr.mem, fx_state, 512); > +} > + > +static int em_fxrstor(struct x86_emulate_ctxt *ctxt) > +{ > + char fx_state[512] __aligned(16); > + int rc; > + > + rc = check_fxsr(ctxt); Is this check enough here ? What I mean is that is it possible that the memory image that is read from has data in an invalid format/corrupt or is that irrelevant ? Bandan > + if (rc != X86EMUL_CONTINUE) > + return rc; > + > + rc = segmented_read(ctxt, ctxt->memop.addr.mem, fx_state, 512); > + if (rc != X86EMUL_CONTINUE) > + return rc; > + > + ctxt->ops->get_fpu(ctxt); > +#ifdef CONFIG_X86_64 > + if (ctxt->rex_prefix & (1 << 3)) > + asm volatile("fxrstor64 %0" : "+m"(fx_state)); > + else > +#endif > + asm volatile("fxrstor %0" : "+m"(fx_state)); > + ctxt->ops->put_fpu(ctxt); > + > + return X86EMUL_CONTINUE; > +} > + > static bool valid_cr(int nr) > { > switch (nr) { > @@ -4208,7 +4281,9 @@ static const struct gprefix pfx_0f_ae_7 = { > }; > > static const struct group_dual group15 = { { > - N, N, N, N, N, N, N, GP(0, &pfx_0f_ae_7), > + I(ModRM | Aligned16, em_fxsave), > + I(ModRM | Aligned16, em_fxrstor), > + N, N, N, N, N, GP(0, &pfx_0f_ae_7), > }, { > N, N, N, N, N, N, N, N, > } };