KVM: x86: Defer the MMU unload to the normal path on an global INVPCID

BugLink: https://bugs.launchpad.net/bugs/1929455
commit f66c53b3b94f658590e1012bf6d922f8b7e01bda upstream.

Defer unloading the MMU after a INVPCID until the instruction emulation
has completed, i.e. until after RIP has been updated.

On VMX, this is a benign bug as VMX doesn't touch the MMU when skipping
an emulated instruction.  However, on SVM, if nrip is disabled, the
emulator is used to skip an instruction, which would lead to fireworks
if the emulator were invoked without a valid MMU.

Fixes: eb4b248e152d ("kvm: vmx: Support INVPCID in shadow paging mode")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210305011101.3597423-15-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kelsey Skunberg <kelsey.skunberg@canonical.com>

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index b5500dd0ffbe403be39315ab3b196ca3582748af..1acd70a662be380cf97bdaae55687ff8b76259e2 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -11407,7 +11407,7 @@ int kvm_handle_invpcid(struct kvm_vcpu *vcpu, unsigned long type, gva_t gva)
 
                fallthrough;
        case INVPCID_TYPE_ALL_INCL_GLOBAL:
-               kvm_mmu_unload(vcpu);
+               kvm_make_request(KVM_REQ_MMU_RELOAD, vcpu);
                return kvm_skip_emulated_instruction(vcpu);
 
        default: