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authorSean Christopherson <seanjc@google.com>2024-01-09 16:39:38 -0800
committerSean Christopherson <seanjc@google.com>2024-02-22 16:27:41 -0800
commitdafc17dd529a6194e199b837916062090562ff80 (patch)
tree80a168a0ebff73e60d62a296152f4f3d5dd15548 /virt
parent322d79f1db4b033844dcb2de43abd570abbd04b4 (diff)
KVM: Add a comment explaining the directed yield pending interrupt logic
Add a comment to explain why KVM treats vCPUs with pending interrupts as in-kernel when a vCPU wants to yield to a vCPU that was preempted while running in kernel mode. Link: https://lore.kernel.org/r/20240110003938.490206-5-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc@google.com>
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/kvm_main.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 9b92858c8b72..c0c2fcdabe1b 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -4090,6 +4090,13 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me, bool yield_to_kernel_mode)
continue;
if (kvm_vcpu_is_blocking(vcpu) && !vcpu_dy_runnable(vcpu))
continue;
+
+ /*
+ * Treat the target vCPU as being in-kernel if it has a
+ * pending interrupt, as the vCPU trying to yield may
+ * be spinning waiting on IPI delivery, i.e. the target
+ * vCPU is in-kernel for the purposes of directed yield.
+ */
if (READ_ONCE(vcpu->preempted) && yield_to_kernel_mode &&
!kvm_arch_dy_has_pending_interrupt(vcpu) &&
!kvm_arch_vcpu_preempted_in_kernel(vcpu))