From: Nicholas Piggin npiggin@gmail.com
commit 575cba20c421ecb6b563ae352e4e0468e4ca8b3c upstream.
pseries guest kernels have a FWNMI handler for SRESET and MCE NMIs, which is basically the same as the regular handlers for those interrupts.
The system reset FWNMI handler did not have a KVM guest test in it, although it probably should have because the guest can itself run guests.
Commit 4f50541f6703b ("powerpc/64s/exception: Move all interrupt handlers to new style code gen macros") convert the handler faithfully to avoid a KVM test with a "clever" trick to modify the IKVM_REAL setting to 0 when the fwnmi handler is to be generated (PPC_PSERIES=y). This worked when the KVM test was generated in the interrupt entry handlers, but a later patch moved the KVM test to the common handler, and the common handler macro is expanded below the fwnmi entry. This prevents the KVM test from being generated even for the 0x100 entry point as well.
The result is NMI IPIs in the host kernel when a guest is running will use gest registers. This goes particularly badly when an HPT guest is running and the MMU is set to guest mode.
Remove this trickery and just generate the test always.
Fixes: 9600f261acaa ("powerpc/64s/exception: Move KVM test to common code") Cc: stable@vger.kernel.org # v5.7+ Signed-off-by: Nicholas Piggin npiggin@gmail.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://lore.kernel.org/r/20201114114743.3306283-1-npiggin@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/powerpc/kernel/exceptions-64s.S | 2 -- 1 file changed, 2 deletions(-)
--- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -1000,8 +1000,6 @@ TRAMP_REAL_BEGIN(system_reset_idle_wake) * Vectors for the FWNMI option. Share common code. */ TRAMP_REAL_BEGIN(system_reset_fwnmi) - /* XXX: fwnmi guest could run a nested/PR guest, so why no test? */ - __IKVM_REAL(system_reset)=0 GEN_INT_ENTRY system_reset, virt=0
#endif /* CONFIG_PPC_PSERIES */