Provide a dedicated helper to query if a *different* vCPU was preempted
in-kernel. x86's VMX is an oddball and can only check if the vCPU is in
kernel (versus userspace) if the vCPU is loaded on the current pCPU.
The existing kvm_arch_vcpu_in_kernel() "works", but it's an ugly mess as
KVM x86 is forced to check kvm_get_running_vcpu() to effectively undo the
multiplexing.
Note, I was sorely tempted to eliminate kvm_arch_dy_has_pending_interrupt()
and bury that logic in VMX code, but I ultimately decided to keep it as an
arch hook as it's entirely plausible that some other architecture can do
cross-vCPU IRQ checks, and if KVM is going to have the (somewhat dubious
IMO) logic, it's probably best to keep it in common code.
Sean Christopherson (4):
KVM: Add dedicated arch hook for querying if vCPU was preempted
in-kernel
KVM: x86: Rely solely on preempted_in_kernel flag for directed yield
KVM: x86: Clean up directed yield API for "has pending interrupt"
KVM: Add a comment explaining the directed yield pending interrupt
logic
arch/x86/kvm/x86.c | 16 +++++++---------
include/linux/kvm_host.h | 1 +
virt/kvm/kvm_main.c | 22 ++++++++++++++++++++--
3 files changed, 28 insertions(+), 11 deletions(-)
base-commit: 1c6d984f523f67ecfad1083bb04c55d91977bb15
--
2.43.0.472.g3155946c3a-goog