powerpc/64s/exception: Move KVM test to common code
This allows more code to be moved out of unrelocated regions. The system call KVMTEST is changed to be open-coded and remain in the tramp area to avoid having to move it to entry_64.S. The custom nature of the system call entry code means the hcall case can be made more streamlined than regular interrupt handlers. mpe: Incorporate fix from Nick: Moving KVM test to the common entry code missed the case of HMI and MCE, which do not do __GEN_COMMON_ENTRY (because they don't want to switch to virt mode). This means a MCE or HMI exception that is taken while KVM is running a guest context will not be switched out of that context, and KVM won't be notified. Found by running sigfuz in guest with patched host on POWER9 DD2.3, which causes some TM related HMI interrupts (which are expected and supposed to be handled by KVM). This fix adds a __GEN_REALMODE_COMMON_ENTRY for those handlers to add the KVM test. This makes them look a little more like other handlers that all use __GEN_COMMON_ENTRY. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200225173541.1549955-13-npiggin@gmail.com
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