From: Nicholas Piggin npiggin@gmail.com
[ Upstream commit 1782663897945a5cf28e564ba5eed730098e9aa4 ]
After the L1 saves its PMU SPRs but before loading the L2's PMU SPRs, switch the pmcregs_in_use field in the L1 lppaca to the value advertised by the L2 in its VPA. On the way out of the L2, set it back after saving the L2 PMU registers (if they were in-use).
This transfers the PMU liveness indication between the L1 and L2 at the points where the registers are not live.
This fixes the nested HV bug for which a workaround was added to the L0 HV by commit 63279eeb7f93a ("KVM: PPC: Book3S HV: Always save guest pmu for guest capable of nesting"), which explains the problem in detail. That workaround is no longer required for guests that include this bug fix.
Fixes: 360cae313702 ("KVM: PPC: Book3S HV: Nested guest entry via hypercall") Signed-off-by: Nicholas Piggin npiggin@gmail.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au Reviewed-by: Fabiano Rosas farosas@linux.ibm.com Link: https://lore.kernel.org/r/20210811160134.904987-10-npiggin@gmail.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/powerpc/include/asm/pmc.h | 7 +++++++ arch/powerpc/kvm/book3s_hv.c | 20 ++++++++++++++++++++ 2 files changed, 27 insertions(+)
diff --git a/arch/powerpc/include/asm/pmc.h b/arch/powerpc/include/asm/pmc.h index c6bbe9778d3c..3c09109e708e 100644 --- a/arch/powerpc/include/asm/pmc.h +++ b/arch/powerpc/include/asm/pmc.h @@ -34,6 +34,13 @@ static inline void ppc_set_pmu_inuse(int inuse) #endif }
+#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE +static inline int ppc_get_pmu_inuse(void) +{ + return get_paca()->pmcregs_in_use; +} +#endif + extern void power4_enable_pmcs(void);
#else /* CONFIG_PPC64 */ diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 085fb8ecbf68..af822f09785f 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -59,6 +59,7 @@ #include <asm/kvm_book3s.h> #include <asm/mmu_context.h> #include <asm/lppaca.h> +#include <asm/pmc.h> #include <asm/processor.h> #include <asm/cputhreads.h> #include <asm/page.h> @@ -3852,6 +3853,18 @@ static int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit, cpu_has_feature(CPU_FTR_P9_TM_HV_ASSIST)) kvmppc_restore_tm_hv(vcpu, vcpu->arch.shregs.msr, true);
+#ifdef CONFIG_PPC_PSERIES + if (kvmhv_on_pseries()) { + barrier(); + if (vcpu->arch.vpa.pinned_addr) { + struct lppaca *lp = vcpu->arch.vpa.pinned_addr; + get_lppaca()->pmcregs_in_use = lp->pmcregs_in_use; + } else { + get_lppaca()->pmcregs_in_use = 1; + } + barrier(); + } +#endif kvmhv_load_guest_pmu(vcpu);
msr_check_and_set(MSR_FP | MSR_VEC | MSR_VSX); @@ -3986,6 +3999,13 @@ static int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit, save_pmu |= nesting_enabled(vcpu->kvm);
kvmhv_save_guest_pmu(vcpu, save_pmu); +#ifdef CONFIG_PPC_PSERIES + if (kvmhv_on_pseries()) { + barrier(); + get_lppaca()->pmcregs_in_use = ppc_get_pmu_inuse(); + barrier(); + } +#endif
vc->entry_exit_map = 0x101; vc->in_guest = 0;