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powerpc/pmu: Set pmcregs_in_use in paca when running as LPAR

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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")
Cc: stable@vger.kernel.org # v4.20+
Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190703012022.15644-2-sjitindarsingh@gmail.com
This commit is contained in:
Suraj Jitindar Singh 2019-07-03 11:20:21 +10:00 committed by Michael Ellerman
parent 63279eeb7f
commit 28d2a6e668
1 changed files with 3 additions and 4 deletions
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7
arch/powerpc/include/asm/pmc.h
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@ -26,12 +26,11 @@ static inline void ppc_set_pmu_inuse(int inuse)
if (firmware_has_feature(FW_FEATURE_LPAR)) {
#ifdef CONFIG_PPC_PSERIES
get_lppaca()->pmcregs_in_use = inuse;
#endif
} else {
#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
get_paca()->pmcregs_in_use = inuse;
#endif
}
#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
get_paca()->pmcregs_in_use = inuse;
#endif
#endif
}