Re: [PATCH v3 03/25] x86/hyperv: Update 'struct hv_enlightened_vmcs' definition

Maxim Levitsky
2022-07-12T11:51:24Z

On Fri, 2022-07-08 at 16:42 +0200, Vitaly Kuznetsov wrote:
> Updated Hyper-V Enlightened VMCS specification lists several new
> fields for the following features:
>
> - PerfGlobalCtrl
> - EnclsExitingBitmap
> - Tsc Scaling
> - GuestLbrCtl
> - CET
> - SSP
>
> Update the definition. The updated definition is available only when
> CPUID.0x4000000A.EBX BIT(0) is '1'. Add a define for it as well.
>
> Note: The latest TLFS is available at
> https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/tlfs/tlfs
>
> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> ---
> arch/x86/include/asm/hyperv-tlfs.h | 18 ++++++++++++++++--
> 1 file changed, 16 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
> index 6f0acc45e67a..6f2c3cdacdf4 100644
> --- a/arch/x86/include/asm/hyperv-tlfs.h
> +++ b/arch/x86/include/asm/hyperv-tlfs.h
> @@ -138,6 +138,9 @@
> #define HV_X64_NESTED_GUEST_MAPPING_FLUSH BIT(18)
> #define HV_X64_NESTED_MSR_BITMAP BIT(19)
>

Maybe add a comment that this is undocumented + what that cpuid bit does?

> +/* Nested quirks. These are HYPERV_CPUID_NESTED_FEATURES.EBX bits. */
> +#define HV_X64_NESTED_EVMCS1_2022_UPDATE BIT(0)
> +
> /*
> * This is specific to AMD and specifies that enlightened TLB flush is
> * supported. If guest opts in to this feature, ASID invalidations only
> @@ -559,9 +562,20 @@ struct hv_enlightened_vmcs {
> u64 partition_assist_page;
> u64 padding64_4[4];
> u64 guest_bndcfgs;
> - u64 padding64_5[7];
> + u64 guest_ia32_perf_global_ctrl;
> + u64 guest_ia32_s_cet;
> + u64 guest_ssp;
> + u64 guest_ia32_int_ssp_table_addr;
> + u64 guest_ia32_lbr_ctl;
> + u64 padding64_5[2];

This change looks OK

> u64 xss_exit_bitmap;
> - u64 padding64_6[7];
> + u64 host_ia32_perf_global_ctrl;
> + u64 encls_exiting_bitmap;
> + u64 tsc_multiplier;
> + u64 host_ia32_s_cet;
> + u64 host_ssp;
> + u64 host_ia32_int_ssp_table_addr;
> + u64 padding64_6;

I think we have a mistake here:

UINT64 XssExitingBitmap;
UINT64 EnclsExitingBitmap;
UINT64 HostPerfGlobalCtrl;
UINT64 TscMultiplier;
UINT64 HostSCet;
UINT64 HostSsp;
UINT64 HostInterruptSspTableAddr;
UINT64 Rsvd8;

I think you need to swap encls_exiting_bitmap and host_ia32_perf_global_ctrl

I used https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/tlfs/datatypes/hv_vmx_enlightened_vmcs
as the reference.

Best regards,
Maxim Levitsky

> } __packed;
>
> #define HV_VMX_ENLIGHTENED_CLEAN_FIELD_NONE 0