KVM: PPC: Book3S HV: Don't call real-mode XICS hypercall handlers if not enabled

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commit 00bb6ae500 upstream.

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.

Fixes: 5af5099385 ("KVM: PPC: Book3S HV: Native usage of the XIVE interrupt controller")
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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Paul Mackerras 2017-10-26 17:00:22 +11:00 • committed by Greg Kroah-Hartman

parent 665e661970

commit f5073bc7c1

1 changed files with 12 additions and 0 deletions

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arch/powerpc/kvm/book3s_hv_builtin.c

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