KVM: PPC: Implement MMIO emulation support for Book3S HV guests

This provides the low-level support for MMIO emulation in Book3S HV
guests.  When the guest tries to map a page which is not covered by
any memslot, that page is taken to be an MMIO emulation page.  Instead
of inserting a valid HPTE, we insert an HPTE that has the valid bit
clear but another hypervisor software-use bit set, which we call
HPTE_V_ABSENT, to indicate that this is an absent page.  An
absent page is treated much like a valid page as far as guest hcalls
(H_ENTER, H_REMOVE, H_READ etc.) are concerned, except of course that
an absent HPTE doesn't need to be invalidated with tlbie since it
was never valid as far as the hardware is concerned.

When the guest accesses a page for which there is an absent HPTE, it
will take a hypervisor data storage interrupt (HDSI) since we now set
the VPM1 bit in the LPCR.  Our HDSI handler for HPTE-not-present faults
looks up the hash table and if it finds an absent HPTE mapping the
requested virtual address, will switch to kernel mode and handle the
fault in kvmppc_book3s_hv_page_fault(), which at present just calls
kvmppc_hv_emulate_mmio() to set up the MMIO emulation.

This is based on an earlier patch by Benjamin Herrenschmidt, but since
heavily reworked.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 12 insertions, 9 deletions

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 6ed0a84..45aabb9 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -326,19 +326,18 @@ static int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu,
 		break;
 	}
 	/*
-	 * We get these next two if the guest does a bad real-mode access,
-	 * as we have enabled VRMA (virtualized real mode area) mode in the
-	 * LPCR.  We just generate an appropriate DSI/ISI to the guest.
+	 * We get this if the guest accesses a page which it thinks
+	 * it has mapped but which is not actually present, because
+	 * it is for an emulated I/O device.
+	 * Any other HDSI interrupt has been handled already.
 	 */
 	case BOOK3S_INTERRUPT_H_DATA_STORAGE:
-		vcpu->arch.shregs.dsisr = vcpu->arch.fault_dsisr;
-		vcpu->arch.shregs.dar = vcpu->arch.fault_dar;
-		kvmppc_inject_interrupt(vcpu, BOOK3S_INTERRUPT_DATA_STORAGE, 0);
-		r = RESUME_GUEST;
+		r = kvmppc_book3s_hv_page_fault(run, vcpu,
+				vcpu->arch.fault_dar, vcpu->arch.fault_dsisr);
 		break;
 	case BOOK3S_INTERRUPT_H_INST_STORAGE:
 		kvmppc_inject_interrupt(vcpu, BOOK3S_INTERRUPT_INST_STORAGE,
-					0x08000000);
+					vcpu->arch.shregs.msr & 0x58000000);
 		r = RESUME_GUEST;
 		break;
 	/*
@@ -1195,6 +1194,8 @@ static int kvmppc_hv_setup_rma(struct kvm_vcpu *vcpu)
 
 		/* Update VRMASD field in the LPCR */
 		senc = slb_pgsize_encoding(psize);
+		kvm->arch.vrma_slb_v = senc | SLB_VSID_B_1T |
+			(VRMA_VSID << SLB_VSID_SHIFT_1T);
 		lpcr = kvm->arch.lpcr & ~LPCR_VRMASD;
 		lpcr |= senc << (LPCR_VRMASD_SH - 4);
 		kvm->arch.lpcr = lpcr;
@@ -1291,7 +1292,9 @@ int kvmppc_core_init_vm(struct kvm *kvm)
 		kvm->arch.host_lpcr = lpcr = mfspr(SPRN_LPCR);
 		lpcr &= LPCR_PECE | LPCR_LPES;
 		lpcr |= (4UL << LPCR_DPFD_SH) | LPCR_HDICE |
-			LPCR_VPM0 | LPCR_VRMA_L;
+			LPCR_VPM0 | LPCR_VPM1;
+		kvm->arch.vrma_slb_v = SLB_VSID_B_1T |
+			(VRMA_VSID << SLB_VSID_SHIFT_1T);
 	}
 	kvm->arch.lpcr = lpcr;