whpx: x86: kick out of HLT manually when using the kernel-irqchip
Otherwise, interrupts processed through the cancel vCPU and inject path will not cause the vCPU to go out of its halt state. Signed-off-by: Mohamed Mediouni <mohamed@unpredictable.fr> Link: https://lore.kernel.org/r/20260226181930.53170-3-mohamed@unpredictable.fr Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Mohamed Mediouni committed
Feb 26, 2026 at 19:19 UTC
ca7a6add3bd20267f124ea8bed4391da8ee8e253
1 file changed
+29
target/i386/whpx/whpx-all.c
+29
@@ -1468,6 +1468,16 @@ static void whpx_vcpu_post_run(CPUState *cpu)
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!vcpu->exit_ctx.VpContext.ExecutionState.InterruptShadow;
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}
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+static void whpx_vcpu_kick_out_of_hlt(CPUState *cpu)
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+{
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+ WHV_REGISTER_VALUE reg;
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+ whpx_get_reg(cpu, WHvRegisterInternalActivityState, ®);
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+ if (reg.InternalActivity.HaltSuspend) {
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+ reg.InternalActivity.HaltSuspend = 0;
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+ whpx_set_reg(cpu, WHvRegisterInternalActivityState, reg);
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+ }
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+}
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+
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static void whpx_vcpu_process_async_events(CPUState *cpu)
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{
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X86CPU *x86_cpu = X86_CPU(cpu);
@@ -1775,6 +1785,25 @@ int whpx_vcpu_run(CPUState *cpu)
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cpu->exception_index = EXCP_INTERRUPT;
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ret = 1;
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}
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+ /*
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+ * When the Hyper-V APIC is enabled, to get out of HLT we
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+ * either have to request an interrupt or manually get it away
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+ * from HLT.
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+ *
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+ * We also manually do inject some interrupts via WHvRegisterPendingEvent
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+ * instead of WHVRequestInterrupt, which does not reset the HLT state.
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+ *
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+ * However, even with this done, if the guest does an HLT without
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+ * interrupts enabled (which the test_sti_inhibit KVM unit test does)
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+ * then the guest will stay in HLT forever.
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+ *
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+ * Keep it this way for now, with perhaps adding a heartbeat later
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+ * so that we get the CPU time savings from having Hyper-V handle HLT
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+ * instead of going away from it as soon as possible.
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+ */
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+ if (whpx_irqchip_in_kernel()) {
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+ whpx_vcpu_kick_out_of_hlt(cpu);
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+ }
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break;
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case WHvRunVpExitReasonX64MsrAccess: {
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WHV_REGISTER_VALUE reg_values[3] = {0};