From: Chao Gao <chao.gao@intel.com>
To: "Xin Li (Intel)" <xin@zytor.com>
Cc: <linux-kernel@vger.kernel.org>, <kvm@vger.kernel.org>,
<linux-doc@vger.kernel.org>, <pbonzini@redhat.com>,
<seanjc@google.com>, <corbet@lwn.net>, <tglx@linutronix.de>,
<mingo@redhat.com>, <bp@alien8.de>, <dave.hansen@linux.intel.com>,
<x86@kernel.org>, <hpa@zytor.com>, <luto@kernel.org>,
<peterz@infradead.org>, <andrew.cooper3@citrix.com>,
<hch@infradead.org>
Subject: Re: [PATCH v8 18/21] KVM: nVMX: Add FRED VMCS fields to nested VMX context handling
Date: Tue, 14 Oct 2025 14:57:35 +0800 [thread overview]
Message-ID: <aO30XxyprRrs3pT2@intel.com> (raw)
In-Reply-To: <20251014010950.1568389-19-xin@zytor.com>
> /*
>@@ -2765,6 +2783,18 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12,
> vmcs_write64(GUEST_IA32_PAT, vmx->vcpu.arch.pat);
> }
>
>+ if (!vmx->nested.nested_run_pending ||
>+ !nested_cpu_load_guest_fred_state(vmcs12)) {
>+ vmcs_write64(GUEST_IA32_FRED_CONFIG, vmx->nested.pre_vmenter_fred_config);
>+ vmcs_write64(GUEST_IA32_FRED_RSP1, vmx->nested.pre_vmenter_fred_rsp1);
>+ vmcs_write64(GUEST_IA32_FRED_RSP2, vmx->nested.pre_vmenter_fred_rsp2);
>+ vmcs_write64(GUEST_IA32_FRED_RSP3, vmx->nested.pre_vmenter_fred_rsp3);
>+ vmcs_write64(GUEST_IA32_FRED_STKLVLS, vmx->nested.pre_vmenter_fred_stklvls);
>+ vmcs_write64(GUEST_IA32_FRED_SSP1, vmx->nested.pre_vmenter_fred_ssp1);
>+ vmcs_write64(GUEST_IA32_FRED_SSP2, vmx->nested.pre_vmenter_fred_ssp2);
>+ vmcs_write64(GUEST_IA32_FRED_SSP3, vmx->nested.pre_vmenter_fred_ssp3);
...
>+ }
>+
> vcpu->arch.tsc_offset = kvm_calc_nested_tsc_offset(
> vcpu->arch.l1_tsc_offset,
> vmx_get_l2_tsc_offset(vcpu),
>@@ -3679,6 +3709,18 @@ enum nvmx_vmentry_status nested_vmx_enter_non_root_mode(struct kvm_vcpu *vcpu,
> &vmx->nested.pre_vmenter_ssp,
> &vmx->nested.pre_vmenter_ssp_tbl);
>
>+ if (!vmx->nested.nested_run_pending ||
>+ !nested_cpu_load_guest_fred_state(vmcs12)) {
>+ vmx->nested.pre_vmenter_fred_config = vmcs_read64(GUEST_IA32_FRED_CONFIG);
>+ vmx->nested.pre_vmenter_fred_rsp1 = vmcs_read64(GUEST_IA32_FRED_RSP1);
>+ vmx->nested.pre_vmenter_fred_rsp2 = vmcs_read64(GUEST_IA32_FRED_RSP2);
>+ vmx->nested.pre_vmenter_fred_rsp3 = vmcs_read64(GUEST_IA32_FRED_RSP3);
>+ vmx->nested.pre_vmenter_fred_stklvls = vmcs_read64(GUEST_IA32_FRED_STKLVLS);
>+ vmx->nested.pre_vmenter_fred_ssp1 = vmcs_read64(GUEST_IA32_FRED_SSP1);
>+ vmx->nested.pre_vmenter_fred_ssp2 = vmcs_read64(GUEST_IA32_FRED_SSP2);
>+ vmx->nested.pre_vmenter_fred_ssp3 = vmcs_read64(GUEST_IA32_FRED_SSP3);
FRED state save/restore is needed only when the guest has FRED support. So, the
above save/restore should be guarded by guest_cpu_cap_has(vcpu, X86_FEATURE_FRED).
Otherwise, on hardware without FRED, vmread_error() would be triggered here as
reported by syzbot.
next prev parent reply other threads:[~2025-10-14 6:57 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-14 1:09 [PATCH v8 00/21] Enable FRED with KVM VMX Xin Li (Intel)
2025-10-14 1:09 ` [PATCH v8 01/21] KVM: VMX: Add support for the secondary VM exit controls Xin Li (Intel)
2025-10-14 1:09 ` [PATCH v8 02/21] KVM: VMX: Initialize VM entry/exit FRED controls in vmcs_config Xin Li (Intel)
2025-10-14 1:09 ` [PATCH v8 03/21] KVM: VMX: Disable FRED if FRED consistency checks fail Xin Li (Intel)
2025-10-14 1:09 ` [PATCH v8 04/21] x86/cea: Prefix event stack names with ESTACK_ Xin Li (Intel)
2025-10-23 14:20 ` Dave Hansen
2025-10-14 1:09 ` [PATCH v8 05/21] x86/cea: Export API for per-CPU exception stacks for KVM Xin Li (Intel)
2025-10-23 1:20 ` Xin Li
2025-10-23 8:06 ` Peter Zijlstra
2025-10-23 8:55 ` Xin Li
2025-10-23 14:08 ` Sean Christopherson
2025-10-23 14:15 ` Peter Zijlstra
2025-10-23 15:03 ` Dave Hansen
2025-10-14 1:09 ` [PATCH v8 06/21] KVM: VMX: Initialize VMCS FRED fields Xin Li (Intel)
2025-10-14 1:09 ` [PATCH v8 07/21] KVM: VMX: Set FRED MSR intercepts Xin Li (Intel)
2025-10-14 1:09 ` [PATCH v8 08/21] KVM: VMX: Save/restore guest FRED RSP0 Xin Li (Intel)
2025-10-14 1:09 ` [PATCH v8 09/21] KVM: VMX: Add support for saving and restoring FRED MSRs Xin Li (Intel)
2025-10-14 1:09 ` [PATCH v8 10/21] KVM: x86: Add a helper to detect if FRED is enabled for a vCPU Xin Li (Intel)
2025-10-14 1:09 ` [PATCH v8 11/21] KVM: VMX: Virtualize FRED event_data Xin Li (Intel)
2025-10-14 1:09 ` [PATCH v8 12/21] KVM: VMX: Virtualize FRED nested exception tracking Xin Li (Intel)
2025-10-14 1:09 ` [PATCH v8 13/21] KVM: x86: Save/restore the nested flag of an exception Xin Li (Intel)
2025-10-14 1:09 ` [PATCH v8 14/21] KVM: x86: Mark CR4.FRED as not reserved Xin Li (Intel)
2025-10-14 1:09 ` [PATCH v8 15/21] KVM: VMX: Dump FRED context in dump_vmcs() Xin Li (Intel)
2025-10-14 1:09 ` [PATCH v8 16/21] KVM: x86: Advertise support for FRED Xin Li (Intel)
2025-10-14 1:09 ` [PATCH v8 17/21] KVM: nVMX: Add support for the secondary VM exit controls Xin Li (Intel)
2025-10-14 1:09 ` [PATCH v8 18/21] KVM: nVMX: Add FRED VMCS fields to nested VMX context handling Xin Li (Intel)
2025-10-14 6:57 ` Chao Gao [this message]
2025-10-14 7:49 ` Xin Li
2025-10-22 23:10 ` Xin Li
2025-10-14 1:09 ` [PATCH v8 19/21] KVM: nVMX: Add FRED-related VMCS field checks Xin Li (Intel)
2025-10-14 1:09 ` [PATCH v8 20/21] KVM: nVMX: Add prerequisites to SHADOW_FIELD_R[OW] macros Xin Li (Intel)
2025-10-14 1:09 ` [PATCH v8 21/21] KVM: nVMX: Allow VMX FRED controls Xin Li (Intel)
2025-10-14 6:13 ` [syzbot ci] Re: Enable FRED with KVM VMX syzbot ci
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