KVM: PPC: Book3S HV: Don't access HFSCR, LPIDR or LPCR when running nested

When running as a nested hypervisor, this avoids reading hypervisor
privileged registers (specifically HFSCR, LPIDR and LPCR) at startup;
instead reasonable default values are used.  This also avoids writing
LPIDR in the single-vcpu entry/exit path.

Also, this removes the check for CPU_FTR_HVMODE in kvmppc_mmu_hv_init()
since its only caller already checks this.

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c
index 68e14af..c615617 100644 (file)
--- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
@@ -268,14 +268,13 @@ int kvmppc_mmu_hv_init(void)
 {
        unsigned long host_lpid, rsvd_lpid;
 
-       if (!cpu_has_feature(CPU_FTR_HVMODE))
-               return -EINVAL;
-
        if (!mmu_has_feature(MMU_FTR_LOCKLESS_TLBIE))
                return -EINVAL;
 
        /* POWER7 has 10-bit LPIDs (12-bit in POWER8) */
-       host_lpid = mfspr(SPRN_LPID);
+       host_lpid = 0;
+       if (cpu_has_feature(CPU_FTR_HVMODE))
+               host_lpid = mfspr(SPRN_LPID);
        rsvd_lpid = LPID_RSVD;
 
        kvmppc_init_lpid(rsvd_lpid + 1);

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index f8c14e8..c90deb5 100644 (file)
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -2174,15 +2174,18 @@ static struct kvm_vcpu *kvmppc_core_vcpu_create_hv(struct kvm *kvm,
         * Set the default HFSCR for the guest from the host value.
         * This value is only used on POWER9.
         * On POWER9, we want to virtualize the doorbell facility, so we
-        * turn off the HFSCR bit, which causes those instructions to trap.
+        * don't set the HFSCR_MSGP bit, and that causes those instructions
+        * to trap and then we emulate them.
         */
-       vcpu->arch.hfscr = mfspr(SPRN_HFSCR);
-       if (cpu_has_feature(CPU_FTR_P9_TM_HV_ASSIST))
+       vcpu->arch.hfscr = HFSCR_TAR | HFSCR_EBB | HFSCR_PM | HFSCR_BHRB |
+               HFSCR_DSCR | HFSCR_VECVSX | HFSCR_FP;
+       if (cpu_has_feature(CPU_FTR_HVMODE)) {
+               vcpu->arch.hfscr &= mfspr(SPRN_HFSCR);
+               if (cpu_has_feature(CPU_FTR_P9_TM_HV_ASSIST))
+                       vcpu->arch.hfscr |= HFSCR_TM;
+       }
+       if (cpu_has_feature(CPU_FTR_TM_COMP))
                vcpu->arch.hfscr |= HFSCR_TM;
-       else if (!cpu_has_feature(CPU_FTR_TM_COMP))
-               vcpu->arch.hfscr &= ~HFSCR_TM;
-       if (cpu_has_feature(CPU_FTR_ARCH_300))
-               vcpu->arch.hfscr &= ~HFSCR_MSGP;
 
        kvmppc_mmu_book3s_hv_init(vcpu);
 
@@ -4006,8 +4009,10 @@ int kvmhv_run_single_vcpu(struct kvm_run *kvm_run,
 
        srcu_read_unlock(&kvm->srcu, srcu_idx);
 
-       mtspr(SPRN_LPID, kvm->arch.host_lpid);
-       isync();
+       if (cpu_has_feature(CPU_FTR_HVMODE)) {
+               mtspr(SPRN_LPID, kvm->arch.host_lpid);
+               isync();
+       }
 
        trace_hardirqs_off();
        set_irq_happened(trap);
@@ -4634,9 +4639,13 @@ static int kvmppc_core_init_vm_hv(struct kvm *kvm)
                kvm->arch.host_sdr1 = mfspr(SPRN_SDR1);
 
        /* Init LPCR for virtual RMA mode */
-       kvm->arch.host_lpid = mfspr(SPRN_LPID);
-       kvm->arch.host_lpcr = lpcr = mfspr(SPRN_LPCR);
-       lpcr &= LPCR_PECE | LPCR_LPES;
+       if (cpu_has_feature(CPU_FTR_HVMODE)) {
+               kvm->arch.host_lpid = mfspr(SPRN_LPID);
+               kvm->arch.host_lpcr = lpcr = mfspr(SPRN_LPCR);
+               lpcr &= LPCR_PECE | LPCR_LPES;
+       } else {
+               lpcr = 0;
+       }
        lpcr |= (4UL << LPCR_DPFD_SH) | LPCR_HDICE |
                LPCR_VPM0 | LPCR_VPM1;
        kvm->arch.vrma_slb_v = SLB_VSID_B_1T |