Re: [PATCH v1 05/23] KVM: VMX: Initialize FRED VM entry/exit controls in vmcs_config

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On 8.11.23 г. 20:29 ч., Xin Li wrote:
Setup the global vmcs_config for FRED:
1) Add VM_ENTRY_LOAD_IA32_FRED to KVM_OPTIONAL_VMX_VM_ENTRY_CONTROLS to
    have a FRED CPU load guest FRED MSRs from VMCS upon VM entry.
2) Add SECONDARY_VM_EXIT_SAVE_IA32_FRED to
    KVM_OPTIONAL_VMX_SECONDARY_VM_EXIT_CONTROLS to have a FRED CPU save
    guest FRED MSRs to VMCS during VM exit.
3) add SECONDARY_VM_EXIT_LOAD_IA32_FRED to
    KVM_OPTIONAL_VMX_SECONDARY_VM_EXIT_CONTROLS to have a FRED CPU load
    host FRED MSRs from VMCS during VM exit.

Also add sanity checks to make sure FRED VM entry/exit controls can be
set on a FRED CPU.

Tested-by: Shan Kang <shan.kang@xxxxxxxxx>
Signed-off-by: Xin Li <xin3.li@xxxxxxxxx>
---
  arch/x86/include/asm/vmx.h |  3 +++
  arch/x86/kvm/vmx/vmx.c     | 19 ++++++++++++++++++-
  arch/x86/kvm/vmx/vmx.h     |  7 +++++--
  3 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
index 4d4177ec802c..41796a733bc9 100644
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -106,6 +106,8 @@
  #define VM_EXIT_PT_CONCEAL_PIP			0x01000000
  #define VM_EXIT_CLEAR_IA32_RTIT_CTL		0x02000000
  #define VM_EXIT_ACTIVATE_SECONDARY_CONTROLS	0x80000000
+#define SECONDARY_VM_EXIT_SAVE_IA32_FRED	0x00000001
+#define SECONDARY_VM_EXIT_LOAD_IA32_FRED	0x00000002
#define VM_EXIT_ALWAYSON_WITHOUT_TRUE_MSR 0x00036dff @@ -119,6 +121,7 @@
  #define VM_ENTRY_LOAD_BNDCFGS                   0x00010000
  #define VM_ENTRY_PT_CONCEAL_PIP			0x00020000
  #define VM_ENTRY_LOAD_IA32_RTIT_CTL		0x00040000
+#define VM_ENTRY_LOAD_IA32_FRED			0x00800000
#define VM_ENTRY_ALWAYSON_WITHOUT_TRUE_MSR 0x000011ff diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index df769207cbe0..9186f41974ab 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2694,10 +2694,27 @@ static int setup_vmcs_config(struct vmcs_config *vmcs_conf,
  		_vmexit_control &= ~x_ctrl;
  	}
- if (_vmexit_control & VM_EXIT_ACTIVATE_SECONDARY_CONTROLS)
+	if (_vmexit_control & VM_EXIT_ACTIVATE_SECONDARY_CONTROLS) {
  		_secondary_vmexit_control =
  			adjust_vmx_controls64(KVM_OPTIONAL_VMX_SECONDARY_VM_EXIT_CONTROLS,
  					      MSR_IA32_VMX_EXIT_CTLS2);
+		if (cpu_feature_enabled(X86_FEATURE_FRED) &&
+		    !(_secondary_vmexit_control & SECONDARY_VM_EXIT_SAVE_IA32_FRED &&
+		      _secondary_vmexit_control & SECONDARY_VM_EXIT_LOAD_IA32_FRED)) {

Can those checks actually trigger? I.e if FEATURE_FRED is set it means the CPU implements the FRED spec. According to the spec it's guaranteed that VMX_EXIT_CTLS2 will contain those bits set to 1. So aren't those checks superfluous?

+			pr_warn_once("FRED enabled but no VMX VM-Exit {SAVE,LOAD}_IA32_FRED controls: %llx\n",
+				     _secondary_vmexit_control);
+			if (error_on_inconsistent_vmcs_config)
+				return -EIO;
+		}
+	}
+
+	if (cpu_feature_enabled(X86_FEATURE_FRED) &&
+	    !(_vmentry_control & VM_ENTRY_LOAD_IA32_FRED)) {
DITTO

<snip>




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