From: "Yang, Weijiang" <weijiang.yang@intel.com>
To: Chao Gao <chao.gao@intel.com>
Cc: <seanjc@google.com>, <pbonzini@redhat.com>,
<dave.hansen@intel.com>, <kvm@vger.kernel.org>,
<linux-kernel@vger.kernel.org>, <x86@kernel.org>,
<yuan.yao@linux.intel.com>, <peterz@infradead.org>,
<rick.p.edgecombe@intel.com>, <mlevitsk@redhat.com>,
<john.allen@amd.com>
Subject: Re: [PATCH v9 26/27] KVM: nVMX: Enable CET support for nested guest
Date: Tue, 30 Jan 2024 15:38:36 +0800 [thread overview]
Message-ID: <073cc3da-63ef-4913-9c20-f4fa090751cd@intel.com> (raw)
In-Reply-To: <ZbdOB5YWX8CGsEHC@chao-email>
On 1/29/2024 3:04 PM, Chao Gao wrote:
> On Tue, Jan 23, 2024 at 06:41:59PM -0800, Yang Weijiang wrote:
>> Set up CET MSRs, related VM_ENTRY/EXIT control bits and fixed CR4 setting
>> to enable CET for nested VM.
>>
>> vmcs12 and vmcs02 needs to be synced when L2 exits to L1 or when L1 wants
>> to resume L2, that way correct CET states can be observed by one another.
>>
>> Suggested-by: Chao Gao <chao.gao@intel.com>
>> Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
>> Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
>> ---
>> arch/x86/kvm/vmx/nested.c | 57 +++++++++++++++++++++++++++++++++++++--
>> arch/x86/kvm/vmx/vmcs12.c | 6 +++++
>> arch/x86/kvm/vmx/vmcs12.h | 14 +++++++++-
>> arch/x86/kvm/vmx/vmx.c | 2 ++
>> 4 files changed, 76 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
>> index 468a7cf75035..e330897a7e5e 100644
>> --- a/arch/x86/kvm/vmx/nested.c
>> +++ b/arch/x86/kvm/vmx/nested.c
>> @@ -691,6 +691,28 @@ static inline bool nested_vmx_prepare_msr_bitmap(struct kvm_vcpu *vcpu,
>> nested_vmx_set_intercept_for_msr(vmx, msr_bitmap_l1, msr_bitmap_l0,
>> MSR_IA32_FLUSH_CMD, MSR_TYPE_W);
>>
>> + /* Pass CET MSRs to nested VM if L0 and L1 are set to pass-through. */
>> + nested_vmx_set_intercept_for_msr(vmx, msr_bitmap_l1, msr_bitmap_l0,
>> + MSR_IA32_U_CET, MSR_TYPE_RW);
>> +
>> + nested_vmx_set_intercept_for_msr(vmx, msr_bitmap_l1, msr_bitmap_l0,
>> + MSR_IA32_S_CET, MSR_TYPE_RW);
>> +
>> + nested_vmx_set_intercept_for_msr(vmx, msr_bitmap_l1, msr_bitmap_l0,
>> + MSR_IA32_PL0_SSP, MSR_TYPE_RW);
>> +
>> + nested_vmx_set_intercept_for_msr(vmx, msr_bitmap_l1, msr_bitmap_l0,
>> + MSR_IA32_PL1_SSP, MSR_TYPE_RW);
>> +
>> + nested_vmx_set_intercept_for_msr(vmx, msr_bitmap_l1, msr_bitmap_l0,
>> + MSR_IA32_PL2_SSP, MSR_TYPE_RW);
>> +
>> + nested_vmx_set_intercept_for_msr(vmx, msr_bitmap_l1, msr_bitmap_l0,
>> + MSR_IA32_PL3_SSP, MSR_TYPE_RW);
>> +
>> + nested_vmx_set_intercept_for_msr(vmx, msr_bitmap_l1, msr_bitmap_l0,
>> + MSR_IA32_INT_SSP_TAB, MSR_TYPE_RW);
>> +
>> kvm_vcpu_unmap(vcpu, &vmx->nested.msr_bitmap_map, false);
>>
>> vmx->nested.force_msr_bitmap_recalc = false;
>> @@ -2506,6 +2528,17 @@ static void prepare_vmcs02_rare(struct vcpu_vmx *vmx, struct vmcs12 *vmcs12)
>> if (kvm_mpx_supported() && vmx->nested.nested_run_pending &&
>> (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_BNDCFGS))
>> vmcs_write64(GUEST_BNDCFGS, vmcs12->guest_bndcfgs);
>> +
>> + if (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_CET_STATE) {
>> + if (guest_can_use(&vmx->vcpu, X86_FEATURE_SHSTK)) {
>> + vmcs_writel(GUEST_SSP, vmcs12->guest_ssp);
>> + vmcs_writel(GUEST_INTR_SSP_TABLE,
>> + vmcs12->guest_ssp_tbl);
>> + }
>> + if (guest_can_use(&vmx->vcpu, X86_FEATURE_SHSTK) ||
>> + guest_can_use(&vmx->vcpu, X86_FEATURE_IBT))
>> + vmcs_writel(GUEST_S_CET, vmcs12->guest_s_cet);
>> + }
> I think you need to move this hunk outside the outmost if-statement, i.e.,
>
> if (!hv_evmcs || !(hv_evmcs->hv_clean_fields &
> HV_VMX_ENLIGHTENED_CLEAN_FIELD_GUEST_GRP1)) {
Yes, I should move them to the end of the function, will do it, thanks!
>
> otherwise, the whole block may be skipped (e.g., when evmcs is enabled and
> GUEST_GRP1 is clean), leaving CET state not context-switched.
>
> And if VM_ENTRY_LOAD_CET_STATE of vmcs12 is cleared, L1's values should be
> propagated to vmcs02 on nested VMenter; see pre_vmenter_debugctl in struct
> nested_vmx. I believe we need similar handling for the three CET fields.
The code used to be there, but I thought it's not the valid usage model, so removed them.
After a second thought, I think I shouldn't assume L1's CET usage, just check the flags and
sync CET states between L2<-->L1. Will add the handling, thanks!
>
>> }
>>
>> if (nested_cpu_has_xsaves(vmcs12))
>> @@ -4344,6 +4377,15 @@ static void sync_vmcs02_to_vmcs12_rare(struct kvm_vcpu *vcpu,
>> vmcs12->guest_pending_dbg_exceptions =
>> vmcs_readl(GUEST_PENDING_DBG_EXCEPTIONS);
>>
>> + if (guest_can_use(&vmx->vcpu, X86_FEATURE_SHSTK)) {
>> + vmcs12->guest_ssp = vmcs_readl(GUEST_SSP);
>> + vmcs12->guest_ssp_tbl = vmcs_readl(GUEST_INTR_SSP_TABLE);
>> + }
>> + if (guest_can_use(&vmx->vcpu, X86_FEATURE_SHSTK) ||
>> + guest_can_use(&vmx->vcpu, X86_FEATURE_IBT)) {
>> + vmcs12->guest_s_cet = vmcs_readl(GUEST_S_CET);
>> + }
> unnecessary braces.
Will remove it.
next prev parent reply other threads:[~2024-01-30 7:38 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-24 2:41 [PATCH v9 00/27] Enable CET Virtualization Yang Weijiang
2024-01-24 2:41 ` [PATCH v9 01/27] x86/fpu/xstate: Always preserve non-user xfeatures/flags in __state_perm Yang Weijiang
2024-01-30 1:29 ` Edgecombe, Rick P
2024-01-24 2:41 ` [PATCH v9 02/27] x86/fpu/xstate: Refine CET user xstate bit enabling Yang Weijiang
2024-01-24 2:41 ` [PATCH v9 03/27] x86/fpu/xstate: Add CET supervisor mode state support Yang Weijiang
2024-01-24 2:41 ` [PATCH v9 04/27] x86/fpu/xstate: Introduce XFEATURE_MASK_KERNEL_DYNAMIC xfeature set Yang Weijiang
2024-01-24 2:41 ` [PATCH v9 05/27] x86/fpu/xstate: Introduce fpu_guest_cfg for guest FPU configuration Yang Weijiang
2024-01-30 1:29 ` Edgecombe, Rick P
2024-01-30 15:00 ` Yang, Weijiang
2024-01-24 2:41 ` [PATCH v9 06/27] x86/fpu/xstate: Create guest fpstate with guest specific config Yang Weijiang
2024-01-30 1:38 ` Edgecombe, Rick P
2024-01-30 14:54 ` Yang, Weijiang
2024-01-24 2:41 ` [PATCH v9 07/27] x86/fpu/xstate: Warn if kernel dynamic xfeatures detected in normal fpstate Yang Weijiang
2024-01-24 2:41 ` [PATCH v9 08/27] KVM: x86: Rework cpuid_get_supported_xcr0() to operate on vCPU data Yang Weijiang
2024-01-24 2:41 ` [PATCH v9 09/27] KVM: x86: Rename kvm_{g,s}et_msr() to menifest emulation operations Yang Weijiang
2024-01-25 3:43 ` Chao Gao
2024-01-24 2:41 ` [PATCH v9 10/27] KVM: x86: Refine xsave-managed guest register/MSR reset handling Yang Weijiang
2024-01-25 10:17 ` Chao Gao
2024-01-26 9:13 ` Yang, Weijiang
2024-01-24 2:41 ` [PATCH v9 11/27] KVM: x86: Add kvm_msr_{read,write}() helpers Yang Weijiang
2024-01-24 2:41 ` [PATCH v9 12/27] KVM: x86: Report XSS as to-be-saved if there are supported features Yang Weijiang
2024-01-25 10:37 ` Chao Gao
2024-01-24 2:41 ` [PATCH v9 13/27] KVM: x86: Refresh CPUID on write to guest MSR_IA32_XSS Yang Weijiang
2024-01-25 10:57 ` Chao Gao
2024-01-26 9:30 ` Yang, Weijiang
2024-01-24 2:41 ` [PATCH v9 14/27] KVM: x86: Initialize kvm_caps.supported_xss Yang Weijiang
2024-01-26 1:35 ` Chao Gao
2024-01-24 2:41 ` [PATCH v9 15/27] KVM: x86: Load guest FPU state when access XSAVE-managed MSRs Yang Weijiang
2024-01-24 2:41 ` [PATCH v9 16/27] KVM: x86: Add fault checks for guest CR4.CET setting Yang Weijiang
2024-01-24 2:41 ` [PATCH v9 17/27] KVM: x86: Report KVM supported CET MSRs as to-be-saved Yang Weijiang
2024-01-24 2:41 ` [PATCH v9 18/27] KVM: VMX: Introduce CET VMCS fields and control bits Yang Weijiang
2024-01-24 2:41 ` [PATCH v9 19/27] KVM: x86: Use KVM-governed feature framework to track "SHSTK/IBT enabled" Yang Weijiang
2024-01-24 2:41 ` [PATCH v9 20/27] KVM: VMX: Emulate read and write to CET MSRs Yang Weijiang
2024-01-24 2:41 ` [PATCH v9 21/27] KVM: x86: Save and reload SSP to/from SMRAM Yang Weijiang
2024-01-26 3:17 ` Chao Gao
2024-01-26 6:51 ` Chao Gao
2024-01-24 2:41 ` [PATCH v9 22/27] KVM: VMX: Set up interception for CET MSRs Yang Weijiang
2024-01-26 3:54 ` Chao Gao
2024-01-26 9:36 ` Yang, Weijiang
2024-01-24 2:41 ` [PATCH v9 23/27] KVM: VMX: Set host constant supervisor states to VMCS fields Yang Weijiang
2024-01-26 6:31 ` Chao Gao
2024-01-26 9:37 ` Yang, Weijiang
2024-01-24 2:41 ` [PATCH v9 24/27] KVM: x86: Enable CET virtualization for VMX and advertise to userspace Yang Weijiang
2024-01-26 7:50 ` Chao Gao
2024-01-26 12:54 ` Yang, Weijiang
2024-01-24 2:41 ` [PATCH v9 25/27] KVM: nVMX: Introduce new VMX_BASIC bit for event error_code delivery to L1 Yang Weijiang
2024-01-26 7:54 ` Chao Gao
2024-01-24 2:41 ` [PATCH v9 26/27] KVM: nVMX: Enable CET support for nested guest Yang Weijiang
2024-01-29 7:04 ` Chao Gao
2024-01-30 7:38 ` Yang, Weijiang [this message]
2024-01-24 2:42 ` [PATCH v9 27/27] KVM: x86: Stop emulating for CET protected branch instructions Yang Weijiang
2024-01-26 8:53 ` Chao Gao
2024-01-26 12:56 ` Yang, Weijiang
2024-01-30 1:40 ` [PATCH v9 00/27] Enable CET Virtualization Edgecombe, Rick P
2024-01-30 15:05 ` Yang, Weijiang
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