KVM: x86: Invoke kvm_mmu_unload() directly on CR4.PCIDE change

Replace a KVM_REQ_MMU_RELOAD request with a direct kvm_mmu_unload() call
when the guest's CR4.PCIDE changes.  This will allow tweaking the logic
of KVM_REQ_MMU_RELOAD to free only obsolete/invalid roots, which is the
historical intent of KVM_REQ_MMU_RELOAD.  The recent PCIDE behavior is
the only user of KVM_REQ_MMU_RELOAD that doesn't mark affected roots as
obsolete, needs to unconditionally unload the entire MMU, _and_ affects
only the current vCPU.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220225182248.3812651-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index fce6bc707122069e9a982decfa39d56cff0ddf4b..18977693517a42015cafdffe9bd0eb0cc516a117 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1079,7 +1079,7 @@ void kvm_post_set_cr4(struct kvm_vcpu *vcpu, unsigned long old_cr4, unsigned lon
         */
        if (!tdp_enabled &&
            (cr4 & X86_CR4_PCIDE) && !(old_cr4 & X86_CR4_PCIDE))
-               kvm_make_request(KVM_REQ_MMU_RELOAD, vcpu);
+               kvm_mmu_unload(vcpu);
 
        /*
         * The TLB has to be flushed for all PCIDs if any of the following