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H A D | book3s_hv_builtin.c | 00bb6ae5 Thu Oct 26 01:00:22 CDT 2017 Paul Mackerras <paulus@ozlabs.org> KVM: PPC: Book3S HV: Don't call real-mode XICS hypercall handlers if not enabled
When running a guest on a POWER9 system with the in-kernel XICS emulation disabled (for example by running QEMU with the parameter "-machine pseries,kernel_irqchip=off"), the kernel does not pass the XICS-related hypercalls such as H_CPPR up to userspace for emulation there as it should.
The reason for this is that the real-mode handlers for these hypercalls don't check whether a XICS device has been instantiated before calling the xics-on-xive code. That code doesn't check either, leading to potential NULL pointer dereferences because vcpu->arch.xive_vcpu is NULL. Those dereferences won't cause an exception in real mode but will lead to kernel memory corruption.
This fixes it by adding kvmppc_xics_enabled() checks before calling the XICS functions.
Cc: stable@vger.kernel.org # v4.11+ Fixes: 5af50993850a ("KVM: PPC: Book3S HV: Native usage of the XIVE interrupt controller") Signed-off-by: Paul Mackerras <paulus@ozlabs.org> 00bb6ae5 Thu Oct 26 01:00:22 CDT 2017 Paul Mackerras <paulus@ozlabs.org> KVM: PPC: Book3S HV: Don't call real-mode XICS hypercall handlers if not enabled When running a guest on a POWER9 system with the in-kernel XICS emulation disabled (for example by running QEMU with the parameter "-machine pseries,kernel_irqchip=off"), the kernel does not pass the XICS-related hypercalls such as H_CPPR up to userspace for emulation there as it should. The reason for this is that the real-mode handlers for these hypercalls don't check whether a XICS device has been instantiated before calling the xics-on-xive code. That code doesn't check either, leading to potential NULL pointer dereferences because vcpu->arch.xive_vcpu is NULL. Those dereferences won't cause an exception in real mode but will lead to kernel memory corruption. This fixes it by adding kvmppc_xics_enabled() checks before calling the XICS functions. Cc: stable@vger.kernel.org # v4.11+ Fixes: 5af50993850a ("KVM: PPC: Book3S HV: Native usage of the XIVE interrupt controller") Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
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