KVM: nVMX: Do a bitwise-AND of regs_avail when switching active VMCS

When switching between vmcs01 and vmcs02, do a bitwise-AND of regs_avail
to effectively reset the mask for the new VMCS, purely to be consistent
with all other "full" writes of regs_avail.  In practice, a straight write
versus a bitwise-AND will yield the same result, as kvm_arch_vcpu_create()
marks *all* registers available (and dirty), and KVM never marks registers
unavailable unless they're lazily loaded.

This will allow adding wrapper APIs to set regs_{avail,dirty} without
having to add special handling for a nVMX use case that doesn't exist in
practice.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
Tested-by: Kai Huang <kai.huang@intel.com>
Message-ID: <20260409224236.2021562-4-seanjc@google.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 22b1f06a9d403e87fec7501a742b1820a0795785..63c4ca8c97d58308e8c2ba66a3155ee8d9c8a077 100644 (file)
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -310,7 +310,7 @@ static void vmx_switch_vmcs(struct kvm_vcpu *vcpu, struct loaded_vmcs *vmcs)
        vmx_sync_vmcs_host_state(vmx, prev);
        put_cpu();
 
-       vcpu->arch.regs_avail = ~VMX_REGS_LAZY_LOAD_SET;
+       vcpu->arch.regs_avail &= ~VMX_REGS_LAZY_LOAD_SET;
 
        /*
         * All lazily updated registers will be reloaded from VMCS12 on both