From: Yang Weijiang <weijiang.yang@intel.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: pbonzini@redhat.com, rkrcmar@redhat.com, jmattson@google.com,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
mst@redhat.com, yu-cheng.yu@intel.com,
Zhang Yi Z <yi.z.zhang@linux.intel.com>,
weijiang.yang@intel.com
Subject: Re: [PATCH v3 7/8] KVM:X86: Add XSS bit 11 and 12 support for CET xsaves/xrstors.
Date: Thu, 28 Feb 2019 16:44:04 +0800 [thread overview]
Message-ID: <20190228084404.GD12006@local-michael-cet-test.sh.intel.com> (raw)
In-Reply-To: <20190228162512.GG6166@linux.intel.com>
On Thu, Feb 28, 2019 at 08:25:12AM -0800, Sean Christopherson wrote:
> On Mon, Feb 25, 2019 at 09:27:15PM +0800, Yang Weijiang wrote:
> > For Guest XSS, right now, only bit 11(user states) and bit 12
> > (supervisor states) are supported, if other bits are being set,
> > need to modify KVM_SUPPORTED_XSS macro to have support.
>
> The changelog should describe what the change does directly. Referencing
> specific bits implies that the code is explicitly checking for said bits,
> which it does not. And there's no need to advise readers on how to add
> more bits in the future, e.g. the KVM_SUPPORTED_XSS macro may not exist
> the next time new bits are added. Just cover what the patch does and why.
>
> Something like:
>
> KVM: x86: Allow the guest to set supported bits in XSS
>
> ...now that KVM supports setting CET related bits. Previously, KVM did
> not support setting any bits in XSS and so hardcoded its check to inject
> a #GP if the guest attempted to write a non-zero value to IA32_XSS.
>
good point! Will change these description.
> >
> > Signed-off-by: Zhang Yi Z <yi.z.zhang@linux.intel.com>
> > Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
> > ---
> > arch/x86/kvm/vmx.c | 8 +++++---
> > 1 file changed, 5 insertions(+), 3 deletions(-)
> >
> > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> > index d32cee9ee079..68908ed7b151 100644
> > --- a/arch/x86/kvm/vmx.c
> > +++ b/arch/x86/kvm/vmx.c
> > @@ -47,6 +47,7 @@
> > #include <asm/virtext.h>
> > #include <asm/mce.h>
> > #include <asm/fpu/internal.h>
> > +#include <asm/fpu/types.h>
> > #include <asm/perf_event.h>
> > #include <asm/debugreg.h>
> > #include <asm/kexec.h>
> > @@ -4336,12 +4337,13 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
> > case MSR_IA32_XSS:
> > if (!vmx_xsaves_supported())
> > return 1;
> > +
> > /*
> > - * The only supported bit as of Skylake is bit 8, but
> > - * it is not supported on KVM.
> > + * Check bits being set are supported in KVM.
>
> I'd drop the comment altogether, it's pretty obvious from the code that
> were checking which bits are supported.
you won't see these redundancies in next version ;)
> > */
> > - if (data != 0)
> > + if (data & ~kvm_supported_xss())
> > return 1;
> > +
> > vcpu->arch.ia32_xss = data;
> > if (vcpu->arch.ia32_xss != host_xss)
> > add_atomic_switch_msr(vmx, MSR_IA32_XSS,
> > --
> > 2.17.1
> >
next prev parent reply other threads:[~2019-03-01 1:49 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-25 13:27 [PATCH v3 0/8] This patch-set is to enable Guest CET support Yang Weijiang
2019-02-25 13:27 ` [PATCH v3 1/8] KVM:VMX: Define CET VMCS fields and bits Yang Weijiang
2019-02-26 19:31 ` Jim Mattson
2019-02-26 7:52 ` Yang Weijiang
2019-02-28 15:53 ` Sean Christopherson
2019-02-28 9:51 ` Yang Weijiang
2019-02-25 13:27 ` [PATCH v3 2/8] KVM:CPUID: Define CET CPUID bits and CR4.CET master enable bit Yang Weijiang
2019-02-26 19:48 ` Jim Mattson
2019-02-26 7:57 ` Yang Weijiang
2019-03-01 2:15 ` Xiaoyao Li
2019-02-28 16:04 ` Sean Christopherson
2019-02-28 8:10 ` Yang Weijiang
2019-02-25 13:27 ` [PATCH v3 3/8] KVM:CPUID: Add CPUID support for Guest CET Yang Weijiang
2019-02-28 15:59 ` Sean Christopherson
2019-02-28 8:28 ` Yang Weijiang
2019-03-01 14:53 ` Sean Christopherson
2019-03-03 9:36 ` Yang Weijiang
2019-03-04 18:28 ` Sean Christopherson
2019-03-04 12:17 ` Yang Weijiang
2019-03-04 18:47 ` Sean Christopherson
2019-03-04 10:01 ` Yang Weijiang
2019-03-04 18:54 ` Sean Christopherson
2019-03-04 10:11 ` Yang Weijiang
2019-03-08 11:32 ` Paolo Bonzini
2019-03-10 12:18 ` Yang Weijiang
2019-02-25 13:27 ` [PATCH v3 4/8] KVM:CPUID: Fix xsaves area size calculation for CPUID.(EAX=0xD,ECX=1) Yang Weijiang
2019-02-25 13:27 ` [PATCH v3 5/8] KVM:VMX: Pass through host CET related MSRs to Guest Yang Weijiang
2019-03-04 18:53 ` Sean Christopherson
2019-03-04 10:07 ` Yang Weijiang
2019-03-05 3:21 ` Sean Christopherson
2019-02-25 13:27 ` [PATCH v3 6/8] KVM:VMX: Load Guest CET via VMCS when CET is enabled in Guest Yang Weijiang
2019-02-28 16:17 ` Sean Christopherson
2019-02-28 8:38 ` Yang Weijiang
2019-03-01 14:58 ` Sean Christopherson
2019-03-03 12:26 ` Yang Weijiang
2019-03-04 18:43 ` Sean Christopherson
2019-03-04 9:56 ` Yang Weijiang
2019-03-05 3:12 ` Sean Christopherson
2019-03-04 12:36 ` Yang Weijiang
2019-03-08 16:28 ` Sean Christopherson
2019-03-08 16:36 ` Paolo Bonzini
2019-02-25 13:27 ` [PATCH v3 7/8] KVM:X86: Add XSS bit 11 and 12 support for CET xsaves/xrstors Yang Weijiang
2019-02-28 16:25 ` Sean Christopherson
2019-02-28 8:44 ` Yang Weijiang [this message]
2019-03-08 11:32 ` Paolo Bonzini
2019-03-10 12:20 ` Yang Weijiang
2019-03-10 13:35 ` Yang Weijiang
2019-03-11 15:32 ` Paolo Bonzini
2019-03-12 14:30 ` Yang Weijiang
2019-03-08 10:49 ` Paolo Bonzini
2019-03-11 1:29 ` Kang, Luwei
2019-02-25 13:27 ` [PATCH v3 8/8] KVM:X86: Add user-space read/write interface for CET MSRs Yang Weijiang
2019-02-28 16:32 ` Sean Christopherson
2019-02-28 9:41 ` Yang Weijiang
2019-03-08 17:30 ` Sean Christopherson
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