Commit def9d705 authored Aug 30, 2022 by Sean Christopherson Committed by Paolo Bonzini Sep 26, 2022

KVM: nVMX: Don't propagate vmcs12's PERF_GLOBAL_CTRL settings to vmcs02



Don't propagate vmcs12's VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL to vmcs02.
KVM doesn't disallow L1 from using VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL
even when KVM itself doesn't use the control, e.g. due to the various
CPU errata that where the MSR can be corrupted on VM-Exit.

Preserve KVM's (vmcs01) setting to hopefully avoid having to toggle the
bit in vmcs02 at a later point.  E.g. if KVM is loading PERF_GLOBAL_CTRL
when running L1, then odds are good KVM will also load the MSR when
running L2.

Fixes: 8bf00a52 ("KVM: VMX: add support for switching of PERF_GLOBAL_CTRL")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/20220830133737.1539624-18-vkuznets@redhat.com


Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

parent 9bcb9065

arch/x86/kvm/vmx/nested.c

+6 −1

Original line number	Diff line number	Diff line
		@@ -2359,9 +2359,14 @@ static void prepare_vmcs02_early(struct vcpu_vmx vmx, struct loaded_vmcs vmcs0
		* are emulated by vmx_set_efer() in prepare_vmcs02(), but speculate
		* on the related bits (if supported by the CPU) in the hope that
		* we can avoid VMWrites during vmx_set_efer().
		*
		* Similarly, take vmcs01's PERF_GLOBAL_CTRL in the hope that if KVM is
		* loading PERF_GLOBAL_CTRL via the VMCS for L1, then KVM will want to
		* do the same for L2.
		*/
		exec_control = __vm_entry_controls_get(vmcs01);
		exec_control \|= vmcs12->vm_entry_controls;
		exec_control \|= (vmcs12->vm_entry_controls &
		~VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL);
		exec_control &= ~(VM_ENTRY_IA32E_MODE \| VM_ENTRY_LOAD_IA32_EFER);
		if (cpu_has_load_ia32_efer()) {
		if (guest_efer & EFER_LMA)