From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wanpeng Li Subject: Re: [CFT PATCH v2 0/2] KVM: support XSAVES usage in the host Date: Wed, 26 Nov 2014 09:24:39 +0800 Message-ID: <20141126012439.GA20090@kernel> References: <1416847414-22253-1-git-send-email-pbonzini@redhat.com> <20141125101331.GA28985@kernel> <54745BB0.8080304@redhat.com> <400361E2-995A-44B4-B35A-0D35793B49DD@gmail.com> <54748F70.70402@redhat.com> Reply-To: Wanpeng Li Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Paolo Bonzini , linux-kernel@vger.kernel.org, kvm list , namit@cs.technion.ac.il, hpa@linux.intel.com To: Nadav Amit Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org Hi all, On Tue, Nov 25, 2014 at 04:50:06PM +0200, Nadav Amit wrote: > >> On Nov 25, 2014, at 16:17, Paolo Bonzini wrote= : >>=20 >>=20 >>=20 >> On 25/11/2014 15:05, Nadav Amit wrote: >>>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c >>>> index 373b0ab9a32e..ca26681455c2 100644 >>>> --- a/arch/x86/kvm/x86.c >>>> +++ b/arch/x86/kvm/x86.c >>>> @@ -6955,6 +6955,9 @@ int fx_init(struct kvm_vcpu *vcpu) >>>> return err; >>>>=20 >>>> fpu_finit(&vcpu->arch.guest_fpu); >>>> + if (cpu_has_xsaves) >>>> + vcpu->arch.guest_fpu.state->xsave.xsave_hdr.xcomp_bv =3D >>>> + host_xcr0 | XSTATE_COMPACTION_ENABLED; >>>>=20 >>>> /* >>>> * Ensure guest xcr0 is valid for loading >>>=20 >>> The second version works for me (w/qemu v2.1.0; Linux 3.13 guest). = I Could you try 3.17 guest which has xsaves enabled? Because I'm not sure= if=20 the below codes from Paolo is enough to mask XSAVES, should we also add= =20 =46(XSAVES)? + const u32 kvm_supported_word10_x86_features =3D + F(XSAVEOPT) | F(XSAVEC) | F(XGETBV1); + In addition, the 3.17 guest is still hang as I mentioned even if I add = the=20 =46(XSAVES) to the kvm_supported_word10_x86_features. >>> did not need to apply this patch on top. [although I am not sure wh= ether >>> relying on userspace to call KVM_SET_XSAVE early enough is a good p= ractice]. >>=20 >> Did you actually try the patch? :) If it works, I'm tempted to appl= y it >> anyway. >Yes, I tried it both with and without this patch. >Due to time constraints I only tested minimal functionality (Linux boo= t). >I will run more tests in the near future. Anyhow, you can put the: > >Tested-by: Nadav Amit > >>=20 >>> One disclaimer: Since I got limited time with the machine, I execut= ed >>> a slightly modified kernel/qemu, and not the latest version. >>> Anyhow, I don=E2=80=99t think these differences can have any impact= =2E >>=20 >> Yes, that is no problem. > >I am just worried that Wanpeng reported it fails, while I report it wo= rks... > I have another patch which enable xsaves in KVM and the patch is still under debug with Paolo's patch "KVM: x86: support XSAVES usage in the h= ost", so the 1/2 patch from Paolo can be dropped if my patch is ready. Anyway= , a quick fix is needed before enable xsaves in kvm.=20 Regards, Wanpeng Li=20 >Nadav