linux-kernel - Re: [PATCH v4 12/20] KVM:VMX: Introduce CET VMCS fields and control bits

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Message-ID: <ZMIAF40pG0WCgPNK@chao-email>
Date:   Thu, 27 Jul 2023 13:26:47 +0800
From:   Chao Gao <chao.gao@...el.com>
To:     Yang Weijiang <weijiang.yang@...el.com>
CC:     <seanjc@...gle.com>, <pbonzini@...hat.com>, <peterz@...radead.org>,
        <john.allen@....com>, <kvm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <rick.p.edgecombe@...el.com>,
        <binbin.wu@...ux.intel.com>,
        Zhang Yi Z <yi.z.zhang@...ux.intel.com>
Subject: Re: [PATCH v4 12/20] KVM:VMX: Introduce CET VMCS fields and control
 bits

On Thu, Jul 20, 2023 at 11:03:44PM -0400, Yang Weijiang wrote:
>Two XSAVES state bits are introduced for CET:
>  IA32_XSS:[bit 11]: Control saving/restoring user mode CET states
>  IA32_XSS:[bit 12]: Control saving/restoring supervisor mode CET states.
>
>Six VMCS fields are introduced for CET:
>  {HOST,GUEST}_S_CET: Stores CET settings for kernel mode.
>  {HOST,GUEST}_SSP: Stores shadow stack pointer of current active task/thread.
>  {HOST,GUEST}_INTR_SSP_TABLE: Stores current active MSR_IA32_INT_SSP_TAB.
>
>On Intel platforms, two additional bits are defined in VM_EXIT and VM_ENTRY
>control fields:
>If VM_EXIT_LOAD_HOST_CET_STATE = 1, the host CET states are restored from

Nit: s/VM_EXIT_LOAD_HOST_CET_STATE/VM_EXIT_LOAD_CET_STATE

to align with the name you are actually using.

>the following VMCS fields at VM-Exit:
>  HOST_S_CET
>  HOST_SSP
>  HOST_INTR_SSP_TABLE
>
>If VM_ENTRY_LOAD_GUEST_CET_STATE = 1, the guest CET states are loaded from

Nit: s/VM_ENTRY_LOAD_GUEST_CET_STATE/VM_ENTRY_LOAD_CET_STATE

>the following VMCS fields at VM-Entry:
>  GUEST_S_CET
>  GUEST_SSP
>  GUEST_INTR_SSP_TABLE
>
>Co-developed-by: Zhang Yi Z <yi.z.zhang@...ux.intel.com>
>Signed-off-by: Zhang Yi Z <yi.z.zhang@...ux.intel.com>
>Signed-off-by: Yang Weijiang <weijiang.yang@...el.com>

Reviewed-by: Chao Gao <chao.gao@...el.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 0d02c4aafa6f..db7f93307349 100644
>--- a/arch/x86/include/asm/vmx.h
>+++ b/arch/x86/include/asm/vmx.h
>@@ -104,6 +104,7 @@
> #define VM_EXIT_CLEAR_BNDCFGS                   0x00800000
> #define VM_EXIT_PT_CONCEAL_PIP			0x01000000
> #define VM_EXIT_CLEAR_IA32_RTIT_CTL		0x02000000
>+#define VM_EXIT_LOAD_CET_STATE                  0x10000000
> 
> #define VM_EXIT_ALWAYSON_WITHOUT_TRUE_MSR	0x00036dff
> 
>@@ -117,6 +118,7 @@
> #define VM_ENTRY_LOAD_BNDCFGS                   0x00010000
> #define VM_ENTRY_PT_CONCEAL_PIP			0x00020000
> #define VM_ENTRY_LOAD_IA32_RTIT_CTL		0x00040000
>+#define VM_ENTRY_LOAD_CET_STATE                 0x00100000
> 
> #define VM_ENTRY_ALWAYSON_WITHOUT_TRUE_MSR	0x000011ff
> 
>@@ -345,6 +347,9 @@ enum vmcs_field {
> 	GUEST_PENDING_DBG_EXCEPTIONS    = 0x00006822,
> 	GUEST_SYSENTER_ESP              = 0x00006824,
> 	GUEST_SYSENTER_EIP              = 0x00006826,
>+	GUEST_S_CET                     = 0x00006828,
>+	GUEST_SSP                       = 0x0000682a,
>+	GUEST_INTR_SSP_TABLE            = 0x0000682c,
> 	HOST_CR0                        = 0x00006c00,
> 	HOST_CR3                        = 0x00006c02,
> 	HOST_CR4                        = 0x00006c04,
>@@ -357,6 +362,9 @@ enum vmcs_field {
> 	HOST_IA32_SYSENTER_EIP          = 0x00006c12,
> 	HOST_RSP                        = 0x00006c14,
> 	HOST_RIP                        = 0x00006c16,
>+	HOST_S_CET                      = 0x00006c18,
>+	HOST_SSP                        = 0x00006c1a,
>+	HOST_INTR_SSP_TABLE             = 0x00006c1c
> };
> 
> /*
>-- 
>2.27.0
>