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Currently, the KVM code assumes that if the host kernel is using the XIVE interrupt controller (the new interrupt controller that first appeared in POWER9 systems), then the in-kernel XICS emulation will use the XIVE hardware to deliver interrupts to the guest. However, this only works when the host is running in hypervisor mode and has full access to all of the XIVE functionality. It doesn't work in any nested virtualization scenario, either with PR KVM or nested-HV KVM, because the XICS-on-XIVE code calls directly into the native-XIVE routines, which are not initialized and cannot function correctly because they use OPAL calls, and OPAL is not available in a guest. This means that using the in-kernel XICS emulation in a nested hypervisor that is using XIVE as its interrupt controller will cause a (nested) host kernel crash. To fix this, we change most of the places where the current code calls xive_enabled() to select between the XICS-on-XIVE emulation and the plain XICS emulation to call a new function, xics_on_xive(), which returns false in a guest. However, there is a further twist. The plain XICS emulation has some functions which are used in real mode and access the underlying XICS controller (the interrupt controller of the host) directly. In the case of a nested hypervisor, this means doing XICS hypercalls directly. When the nested host is using XIVE as its interrupt controller, these hypercalls will fail. Therefore this also adds checks in the places where the XICS emulation wants to access the underlying interrupt controller directly, and if that is XIVE, makes the code use the virtual mode fallback paths, which call generic kernel infrastructure rather than doing direct XICS access. Signed-off-by: Paul Mackerras <paulus@ozlabs.org> Reviewed-by: Cédric Le Goater <clg@kaod.org> Signed-off-by: Paul Mackerras <paulus@ozlabs.org> |
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| .. | ||
| boot | ||
| configs | ||
| crypto | ||
| include | ||
| kernel | ||
| kvm | ||
| lib | ||
| math-emu | ||
| mm | ||
| net | ||
| oprofile | ||
| perf | ||
| platforms | ||
| purgatory | ||
| sysdev | ||
| tools | ||
| xmon | ||
| Kbuild | ||
| Kconfig | ||
| Kconfig.debug | ||
| Makefile | ||
| Makefile.postlink | ||