[PATCH v2 18/43] KVM: x86: Invoke kvm_vcpu_block() directly for non-HALTED wait states
From: Sean Christopherson <seanjc@google.com>
Date: 2021-10-09 02:14:20
Also in:
kvm, kvm-riscv, kvmarm, linux-mips, linux-riscv, lkml
Subsystem:
kernel virtual machine for x86 (kvm/x86), the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Sean Christopherson, Paolo Bonzini, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
Call kvm_vcpu_block() directly for all wait states except HALTED so that kvm_vcpu_halt() is no longer a misnomer on x86. Functionally, this means KVM will never attempt halt-polling or adjust vcpu->halt_poll_ns for INIT_RECEIVED (a.k.a. Wait-For-SIPI (WFS)) or AP_RESET_HOLD; UNINITIALIZED is handled in kvm_arch_vcpu_ioctl_run(), and x86 doesn't use any other "wait" states. As mentioned above, the motivation of this is purely so that "halt" isn't overloaded on x86, e.g. in KVM's stats. Skipping halt-polling for WFS (and RESET_HOLD) has no meaningful effect on guest performance as there are typically single-digit numbers of INIT-SIPI sequences per AP vCPU, per boot, versus thousands of HLTs just to boot to console. Reviewed-by: David Matlack <dmatlack@google.com> Signed-off-by: Sean Christopherson <seanjc@google.com> --- arch/x86/kvm/x86.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index cd51f100e906..e0219acfd9cf 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c@@ -9899,7 +9899,10 @@ static inline int vcpu_block(struct kvm *kvm, struct kvm_vcpu *vcpu) if (!kvm_arch_vcpu_runnable(vcpu) && (!kvm_x86_ops.pre_block || static_call(kvm_x86_pre_block)(vcpu) == 0)) { srcu_read_unlock(&kvm->srcu, vcpu->srcu_idx); - kvm_vcpu_halt(vcpu); + if (vcpu->arch.mp_state == KVM_MP_STATE_HALTED) + kvm_vcpu_halt(vcpu); + else + kvm_vcpu_block(vcpu); vcpu->srcu_idx = srcu_read_lock(&kvm->srcu); if (kvm_x86_ops.post_block)
--
2.33.0.882.g93a45727a2-goog
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel