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: 8bf00a529967 ("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>

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 1743319015b7bbd5ef95c300223002451eebea9a..400e015afa64150f04292daafef70539cc9d2c2e 100644 (file)
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -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)