2022-08-30 13:44:32

by Vitaly Kuznetsov

Subject: [PATCH v6 02/33] x86/hyperv: Update 'struct hv_enlightened_vmcs' definition

Updated Hyper-V Enlightened VMCS specification lists several new
fields for the following features:

- PerfGlobalCtrl
- EnclsExitingBitmap
- Tsc Scaling
- GuestLbrCtl
- CET
- SSP

Update the definition.

Note, the updated spec also provides an additional CPUID feature flag,
CPUIDD.0x4000000A.EBX BIT(0), for PerfGlobalCtrl to workaround a Windows
11 quirk. Despite what the TLFS says:

Indicates support for the GuestPerfGlobalCtrl and HostPerfGlobalCtrl
fields in the enlightened VMCS.

guests can safely use the fields if they are enumerated in the
architectural VMX MSRs. I.e. KVM-on-HyperV doesn't need to check the
CPUID bit, but KVM-as-HyperV must ensure the bit is set if PerfGlobalCtrl
fields are exposed to L1.

https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/tlfs/tlfs

Signed-off-by: Vitaly Kuznetsov <[email protected]>
[sean: tweak CPUID name to make it PerfGlobalCtrl only]
Signed-off-by: Sean Christopherson <[email protected]>
---
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..3089ec352743 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)

+/* Nested features #2. These are HYPERV_CPUID_NESTED_FEATURES.EBX bits. */
+#define HV_X64_NESTED_EVMCS1_PERF_GLOBAL_CTRL 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];
u64 xss_exit_bitmap;
- u64 padding64_6[7];
+ u64 encls_exiting_bitmap;
+ u64 host_ia32_perf_global_ctrl;
+ u64 tsc_multiplier;
+ u64 host_ia32_s_cet;
+ u64 host_ssp;
+ u64 host_ia32_int_ssp_table_addr;
+ u64 padding64_6;
} __packed;

#define HV_VMX_ENLIGHTENED_CLEAN_FIELD_NONE 0
--
2.37.2

2022-09-05 18:13:58

by Wei Liu

Subject: Re: [PATCH v6 02/33] x86/hyperv: Update 'struct hv_enlightened_vmcs' definition

On Tue, Aug 30, 2022 at 03:37:06PM +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.
>
> Note, the updated spec also provides an additional CPUID feature flag,
> CPUIDD.0x4000000A.EBX BIT(0), for PerfGlobalCtrl to workaround a Windows
> 11 quirk. Despite what the TLFS says:
>
> Indicates support for the GuestPerfGlobalCtrl and HostPerfGlobalCtrl
> fields in the enlightened VMCS.
>
> guests can safely use the fields if they are enumerated in the
> architectural VMX MSRs. I.e. KVM-on-HyperV doesn't need to check the
> CPUID bit, but KVM-as-HyperV must ensure the bit is set if PerfGlobalCtrl
> fields are exposed to L1.
>
> https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/tlfs/tlfs
>
> Signed-off-by: Vitaly Kuznetsov <[email protected]>
> [sean: tweak CPUID name to make it PerfGlobalCtrl only]
> Signed-off-by: Sean Christopherson <[email protected]>

Acked-by: Wei Liu <[email protected]>