The ability to run nested guests under KVM means that a guest can also
act as a hypervisor for it's own nested guest. Currently
ppc_set_pmu_inuse() assumes that either FW_FEATURE_LPAR is set,
indicating a guest environment, and so sets the pmcregs_in_use flag in
the lppaca, or that it isn't set, indicating a hypervisor environment,
and so sets the pmcregs_in_use flag in the paca.
The pmcregs_in_use flag in the lppaca is used to communicate this
information to a hypervisor and so must be set in a guest environment.
The pmcregs_in_use flag in the paca is used by KVM code to determine
whether the host state of the performance monitoring unit (PMU) must be
saved and restored when running a guest.
Thus when a guest also acts as a hypervisor it must set this bit in both
places since it needs to ensure both that the real hypervisor saves it's
pmu registers when it runs (requires pmcregs_in_use flag in lppaca), and
that it saves it's own pmu registers when running a nested guest
(requires pmcregs_in_use flag in paca).
Modify ppc_set_pmu_inuse() so that the pmcregs_in_use bit is set in both
the lppaca and the paca when a guest (LPAR) is running with the
capability of running it's own guests (CONFIG_KVM_BOOK3S_HV_POSSIBLE).
Fixes: 95a6432ce903 "KVM: PPC: Book3S HV: Streamlined guest entry/exit path on P9 for radix guests"
Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@xxxxxxxxx>
---
arch/powerpc/include/asm/pmc.h | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/include/asm/pmc.h b/arch/powerpc/include/asm/pmc.h
index dc9a1ca70edf..c6bbe9778d3c 100644
--- a/arch/powerpc/include/asm/pmc.h
+++ b/arch/powerpc/include/asm/pmc.h
@@ -27,11 +27,10 @@ static inline void ppc_set_pmu_inuse(int inuse)
#ifdef CONFIG_PPC_PSERIES
get_lppaca()->pmcregs_in_use = inuse;
#endif
- } else {
+ }
#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
- get_paca()->pmcregs_in_use = inuse;
+ get_paca()->pmcregs_in_use = inuse;
#endif
- }
#endif
}
--
2.13.6
