On 08/05/2025 21:30, David Woodhouse wrote:
From: David Woodhouse <dwmw@xxxxxxxxxxxx> To avoid imposing an ordering constraint on userspace, allow 'invalid' event channel targets to be configured in the IRQ routing table. This is the same as accepting interrupts targeted at vCPUs which don't exist yet, which is already the case for both Xen event channels *and* for MSIs (which don't do any filtering of permitted APIC ID targets at all). If userspace actually *triggers* an IRQ with an invalid target, that will fail cleanly, as kvm_xen_set_evtchn_fast() also does the same range check. If KVM enforced that the IRQ target must be valid at the time it is *configured*, that would force userspace to create all vCPUs and do various other parts of setup (in this case, setting the Xen long_mode) before restoring the IRQ table. Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx> --- arch/x86/kvm/xen.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-)
Reviewed-by: Paul Durrant <paul@xxxxxxx>
