KVM: x86: Drop now-superflous setting of l1tf_flush_l1d in vcpu_run()

Now that KVM unconditionally sets l1tf_flush_l1d in kvm_arch_vcpu_load(),
drop the redundant store from vcpu_run().  The flag is cleared only when
VM-Enter is imminent, deep below vcpu_run(), i.e. barring a KVM bug, it's
impossible for l1tf_flush_l1d to be cleared between loading the vCPU and
calling vcpu_run().

Acked-by: Kai Huang <kai.huang@intel.com>
Link: https://lore.kernel.org/r/20240522014013.1672962-7-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 9c9c25e2b1b9ea2d9d7e25708b6175e343d716e2..3038a6fd141b974bd2dee5184950a08a52a1278b 100644 (file)
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6673,9 +6673,10 @@ static noinstr void vmx_l1d_flush(struct kvm_vcpu *vcpu)
                bool flush_l1d;
 
                /*
-                * Clear the per-vcpu flush bit, it gets set again
-                * either from vcpu_run() or from one of the unsafe
-                * VMEXIT handlers.
+                * Clear the per-vcpu flush bit, it gets set again if the vCPU
+                * is reloaded, i.e. if the vCPU is scheduled out or if KVM
+                * exits to userspace, or if KVM reaches one of the unsafe
+                * VMEXIT handlers, e.g. if KVM calls into the emulator.
                 */
                flush_l1d = vcpu->arch.l1tf_flush_l1d;
                vcpu->arch.l1tf_flush_l1d = false;

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 1f3b21fb4add2b71fb4f60fa53a2a1de32abbea0..bbfc3d9bb024bd67e90a58d77af626d874482f0c 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -11253,7 +11253,6 @@ static int vcpu_run(struct kvm_vcpu *vcpu)
        int r;
 
        vcpu->run->exit_reason = KVM_EXIT_UNKNOWN;
-       vcpu->arch.l1tf_flush_l1d = true;
 
        for (;;) {
                /*