Commit cc17b225 authored Sep 08, 2020 by Vitaly Kuznetsov Committed by Paolo Bonzini Sep 12, 2020

x86/kvm: don't forget to ACK async PF IRQ



Merge commit 26d05b36 ("Merge branch 'kvm-async-pf-int' into HEAD")
tried to adapt the new interrupt based async PF mechanism to the newly
introduced IDTENTRY magic but unfortunately it missed the fact that
DEFINE_IDTENTRY_SYSVEC() doesn't call ack_APIC_irq() on its own and
all DEFINE_IDTENTRY_SYSVEC() users have to call it manually.

As the result all multi-CPU KVM guest hang on boot when
KVM_FEATURE_ASYNC_PF_INT is present. The breakage went unnoticed because no
KVM userspace (e.g. QEMU) currently set it (and thus async PF mechanism
is currently disabled) but we're about to change that.

Fixes: 26d05b36 ("Merge branch 'kvm-async-pf-int' into HEAD")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200908135350.355053-3-vkuznets@redhat.com>
Tested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

parent 244081f9

arch/x86/kernel/kvm.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -271,6 +271,8 @@ DEFINE_IDTENTRY_SYSVEC(sysvec_kvm_asyncpf_interrupt)
		struct pt_regs *old_regs = set_irq_regs(regs);
		u32 token;

		ack_APIC_irq();

		inc_irq_stat(irq_hv_callback_count);

		if (__this_cpu_read(apf_reason.enabled)) {

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