From: Yang Weijiang <weijiang.yang@intel.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: "Jim Mattson" <jmattson@google.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Radim Krčmář" <rkrcmar@redhat.com>,
LKML <linux-kernel@vger.kernel.org>,
"kvm list" <kvm@vger.kernel.org>,
"Michael S. Tsirkin" <mst@redhat.com>,
yu-cheng.yu@intel.com, "Zhang Yi Z" <yi.z.zhang@linux.intel.com>
Subject: Re: [PATCH v3 1/8] KVM:VMX: Define CET VMCS fields and bits
Date: Thu, 28 Feb 2019 17:51:17 +0800 [thread overview]
Message-ID: <20190228095116.GA12240@local-michael-cet-test.sh.intel.com> (raw)
In-Reply-To: <20190228155345.GC6166@linux.intel.com>
On Thu, Feb 28, 2019 at 07:53:45AM -0800, Sean Christopherson wrote:
> On Tue, Feb 26, 2019 at 11:31:11AM -0800, Jim Mattson wrote:
> > On Mon, Feb 25, 2019 at 10:32 PM Yang Weijiang <weijiang.yang@intel.com> wrote:
> > >
> > > CET - Control-flow Enforcement Technology, it's used to
> > > protect against return/jump oriented programming (ROP)
> > > attacks. It provides the following capabilities to defend
> > > against ROP/JOP style control-flow subversion attacks:
> > > - Shadow Stack (SHSTK):
> > > A second stack for the program that is
> > > used exclusively for control transfer
> > > operations.
> > > - Indirect Branch Tracking (IBT):
> > > Free branch protection to defend against
> > > Jump/Call Oriented Programming.
> > >
> > > On processors that support CET, VMX saves/restores
> > > the states of IA32_S_CET, SSP and IA32_INTR_SSP_TABL_ADDR MSR
> > > to the VMCS area for Guest/Host unconditionally.
> > >
> > > If VM_EXIT_LOAD_HOST_CET_STATE = 1, the host CET MSRs are
> > > restored from VMCS host-state area at VM exit as follows:
> > >
> > > - HOST_IA32_S_CET: Host supervisor mode IA32_S_CET MSR is loaded
> > > from this field.
> > >
> > > - HOST_SSP : Host SSP is loaded from this field.
> > >
> > > - HOST_INTR_SSP_TABL_ADDR : Host IA32_INTR_SSP_TABL_ADDR
> > > MSR is loaded from this field.
> > >
> > > If VM_ENTRY_LOAD_GUEST_CET_STATE = 1, the guest CET MSRs are loaded
> > > from VMCS guest-state area at VM entry as follows:
> > >
> > > - GUEST_IA32_S_CET : Guest supervisor mode IA32_S_CET MSR is loaded
> > > from this field.
> > >
> > > - GUEST_SSP : Guest SSP is loaded from this field.
> > >
> > > - GUEST_INTR_SSP_TABL_ADDR : Guest IA32_INTR_SSP_TABL_ADDR
> > > MSR is loaded from this field.
> > >
> > > Additionally, to context switch guest and host CET states, the VMM
> > > uses xsaves/xrstors instructions to save/restore the guest CET states
> > > at VM exit/entry. The CET xsave area is within thread_struct.fpu area.
> > > If OS execution flow changes during task switch/interrupt/exception etc.,
> > > the OS also relies on xsaves/xrstors to switch CET states accordingly.
> > >
> > > Signed-off-by: Zhang Yi Z <yi.z.zhang@linux.intel.com>
> > > Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
> > > ---
> > > arch/x86/include/asm/vmx.h | 8 ++++++++
> > > 1 file changed, 8 insertions(+)
> > >
> > > diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
> > > index ade0f153947d..395c1f7e5938 100644
> > > --- a/arch/x86/include/asm/vmx.h
> > > +++ b/arch/x86/include/asm/vmx.h
> > > @@ -98,6 +98,7 @@
> > > #define VM_EXIT_LOAD_IA32_EFER 0x00200000
> > > #define VM_EXIT_SAVE_VMX_PREEMPTION_TIMER 0x00400000
> > > #define VM_EXIT_CLEAR_BNDCFGS 0x00800000
> > > +#define VM_EXIT_LOAD_HOST_CET_STATE 0x10000000
> > >
> > > #define VM_EXIT_ALWAYSON_WITHOUT_TRUE_MSR 0x00036dff
> > >
> > > @@ -109,6 +110,7 @@
> > > #define VM_ENTRY_LOAD_IA32_PAT 0x00004000
> > > #define VM_ENTRY_LOAD_IA32_EFER 0x00008000
> > > #define VM_ENTRY_LOAD_BNDCFGS 0x00010000
> > > +#define VM_ENTRY_LOAD_GUEST_CET_STATE 0x00100000
> > >
> > > #define VM_ENTRY_ALWAYSON_WITHOUT_TRUE_MSR 0x000011ff
> > >
> > > @@ -325,6 +327,9 @@ enum vmcs_field {
> > > GUEST_PENDING_DBG_EXCEPTIONS = 0x00006822,
> > > GUEST_SYSENTER_ESP = 0x00006824,
> > > GUEST_SYSENTER_EIP = 0x00006826,
> > > + GUEST_IA32_S_CET = 0x00006828,
> > > + GUEST_SSP = 0x0000682a,
> > > + GUEST_INTR_SSP_TABL_ADDR = 0x0000682c,
> >
> > Nit: TABL is an unusual abbreviation. Perhaps TBL here and below?
>
> I don't see any reason to abbreviate TABLE, we don't need the two
> characters for anything.
>
> > And why did you drop the 'IA32' here, but not in GUEST_IA32_S_CET above?
> > (It is true that there seems to be no rhyme or reason to the mnemonics
> > chosen here. For example, EFER keeps its IA32, but SYSENTER_EIP
> > doesn't. Sigh.)
>
> My vote is to always drop IA32, IMO it's redundant.
How about GUEST_S_CET, GUEST_SSP and GUEST_INTR_SSP_TABLE?
next prev parent reply other threads:[~2019-03-01 2:56 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 [this message]
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
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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