Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752277AbaKUUGz (ORCPT ); Fri, 21 Nov 2014 15:06:55 -0500 Received: from mail-pd0-f179.google.com ([209.85.192.179]:47377 "EHLO mail-pd0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752016AbaKUUGx (ORCPT ); Fri, 21 Nov 2014 15:06:53 -0500 Message-ID: <546F9B59.7060800@amacapital.net> Date: Fri, 21 Nov 2014 12:06:49 -0800 From: Andy Lutomirski User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: Paolo Bonzini , linux-kernel@vger.kernel.org, kvm@vger.kernel.org CC: Wanpeng Li , Fenghua Yu , stable@vger.kernel.org, Nadav Amit Subject: Re: [CFT PATCH 2/2] KVM: x86: support XSAVES usage in the host References: <1416594678-13011-1-git-send-email-pbonzini@redhat.com> <1416594678-13011-3-git-send-email-pbonzini@redhat.com> In-Reply-To: <1416594678-13011-3-git-send-email-pbonzini@redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/21/2014 10:31 AM, Paolo Bonzini wrote: > Userspace is expecting non-compacted format for KVM_GET_XSAVE, but > struct xsave_struct might be using the compacted format. Convert > in order to preserve userspace ABI. > > Fixes: f31a9f7c71691569359fa7fb8b0acaa44bce0324 > Cc: Fenghua Yu > Cc: stable@vger.kernel.org > Cc: Nadav Amit > Signed-off-by: Paolo Bonzini > --- > arch/x86/kvm/x86.c | 48 +++++++++++++++++++++++++++++++++++++++++++----- > 1 file changed, 43 insertions(+), 5 deletions(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 5337039427c8..7e8a20e5615a 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -3131,15 +3131,53 @@ static int kvm_vcpu_ioctl_x86_set_debugregs(struct kvm_vcpu *vcpu, > return 0; > } > > +#define XSTATE_COMPACTION_ENABLED (1ULL << 63) > + > +static void fill_xsave(u8 *dest, struct kvm_vcpu *vcpu) > +{ > + struct xsave_struct *xsave = &vcpu->arch.guest_fpu.state->xsave; > + u64 xstate_bv = vcpu->arch.guest_supported_xcr0 | XSTATE_FPSSE; > + u64 valid; > + > + /* > + * Copy legacy XSAVE area, to avoid complications with CPUID > + * leaves 0 and 1 in the loop below. > + */ > + memcpy(dest, xsave, XSAVE_HDR_OFFSET); > + > + /* Set XSTATE_BV */ > + *(u64 *)(dest + XSAVE_HDR_OFFSET) = xstate_bv; > + > + /* > + * Copy each region from the possibly compacted offset to the > + * non-compacted offset. > + */ > + valid = xstate_bv & ~XSTATE_FPSSE; > + if (xsave->xsave_hdr.xcomp_bv & XSTATE_COMPACTION_ENABLED) > + valid &= xsave->xsave_hdr.xcomp_bv; > + > + while (valid) { > + u64 feature = valid & -valid; > + int index = fls64(feature) - 1; > + void *src = get_xsave_addr(xsave, feature); > + > + if (src) { > + u32 size, offset, ecx, edx; > + cpuid_count(XSTATE_CPUID, index, > + &size, &offset, &ecx, &edx); > + memcpy(dest + offset, src, size); Is this really the best way to do this? cpuid is serializing, so this is possibly *very* slow. --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/