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From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Yang Weijiang <weijiang.yang@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>
Subject: Re: [PATCH v3 5/8] KVM:VMX: Pass through host CET related MSRs to Guest.
Date: Mon, 4 Mar 2019 19:21:27 -0800	[thread overview]
Message-ID: <20190305032127.GA23534@linux.intel.com> (raw)
In-Reply-To: <20190304100714.GA3683@local-michael-cet-test.sh.intel.com>

On Mon, Mar 04, 2019 at 06:07:14PM +0800, Yang Weijiang wrote:
> On Mon, Mar 04, 2019 at 10:53:27AM -0800, Sean Christopherson wrote:
> > On Mon, Feb 25, 2019 at 09:27:13PM +0800, Yang Weijiang wrote:
> > > The CET runtime settings, i.e., CET state control bits(IA32_U_CET/
> > > IA32_S_CET), CET SSP(IA32_PL3_SSP/IA32_PL0_SSP) and SSP table address
> > > (IA32_INTERRUPT_SSP_TABLE_ADDR) are task/thread specific, therefore,
> > > OS needs to save/restore the states properly during context switch,
> > > e.g., task/thread switching, interrupt/exception handling, it uses
> > > xsaves/xrstors to achieve that.
> > > 
> > > The difference between VMCS CET area fields and xsave CET area, is that
> > > the former is for state retention during Guest/Host context
> > > switch while the latter is for state retention during OS execution.
> > > 
> > > Linux currently doesn't support CPL1 and CPL2, so SSPs for these level
> > > are skipped here.
> > 
> > But don't we want to allow a guest to access the MSRs regardless of
> > the host kernel's behavior?
> >
> Do you see any necessity of exposing the access to guest?

No, but isn't exposing them to the guest effectively free since XSAVES
and XRSTORS will always save/restore them along with SSP0 and SSP3?

  reply	other threads:[~2019-03-05  3:21 UTC|newest]

Thread overview: 56+ 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 [this message]
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
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
2019-03-08 17:30         ` Sean Christopherson

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