Re: [PATCH v1 1/8] kvm:vmx Introduce CET related VMCS field definitions.

Sean Christopherson
2019-01-02T18:09:42Z

On Wed, Dec 26, 2018 at 04:15:25PM +0800, Yang Weijiang wrote:
> VMX relies on these fields to save/restore CET states for
> guest and host. They are added here as VMCS placeholders
> for the function.

The changelog needs a lot more detail on what is saved where and when,
e.g. hardware unconditionally saves the guest MSRs to the VMCS fields
on exit, hence there is no VM_EXIT_SAVE_GUEST_CET_STATE control bit.

It's also worth calling out that the other CET MSRs are saved/loaded
via XSAVES/XRSTORS.

>
> 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..db745a1d49ae 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_INT_SSP_TABL = 0x0000682c,

Dropping a single letter from "TABLE" seems pointless, "INTERRUPT" is
usually "INTR", and the docs I've seen list the name as
IA32_INTERRUPT_SSP_TABLE_ADDR. So maybe?

{GUEST,HOST}_INTR_SSP_TABLE_ADDR

Also, the SSP and INTERRUPT_SSP_TABL_ADDR fields are 64-bit fields, we
we should define the _HIGH variations.

> HOST_CR0 = 0x00006c00,
> HOST_CR3 = 0x00006c02,
> HOST_CR4 = 0x00006c04,
> @@ -337,6 +342,9 @@ enum vmcs_field {
> HOST_IA32_SYSENTER_EIP = 0x00006c12,
> HOST_RSP = 0x00006c14,
> HOST_RIP = 0x00006c16,
> + HOST_IA32_S_CET = 0x00006c18,
> + HOST_SSP = 0x00006c1a,
> + HOST_INT_SSP_TABL = 0x00006c1c
> };
>
> /*
> --
> 2.17.1
>