KVM's paravirtual IPI hypercall is completely broken on 32-bit hosts due to the invocation of kvm_pv_send_ipi() being wrapped with "#ifdef CONFIG_X86_64". All evidence points to this being an inadvertent change that was introduced in v2 of the series[1] when kvm_pv_send_ipi() was reworked, e.g. the initial version[2] wired up the function for all x86 flavors and kvm_pv_send_ipi() itself differentiates between 32-bit and 64-bit hosts. The second patch adds checks on the result of the PV IPI hypercall in the guest to aid in triaging failures, e.g. when running on 32-bit KVM hosts that have not been fixed. [1] https://patchwork.kernel.org/patch/10500887/ [2] https://patchwork.kernel.org/patch/10496067/ Sean Christopherson (2): KVM: x86: Fix PV IPIs for 32-bit KVM host KVM: x86: WARN_ONCE if sending a PV IPI returns a fatal error arch/x86/kernel/kvm.c | 7 +++++-- arch/x86/kvm/x86.c | 2 +- 2 files changed, 6 insertions(+), 3 deletions(-) -- 2.20.1
