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>

2 files changed, 5 insertions, 4 deletions

diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index e7bfcf81b746..8e0db0b12dd0 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -455,6 +455,7 @@ int main(void)
         DEFINE(KVM_LAST_VCPU, offsetof(struct kvm, arch.last_vcpu));
         DEFINE(KVM_LPCR, offsetof(struct kvm, arch.lpcr));
         DEFINE(KVM_RMOR, offsetof(struct kvm, arch.rmor));
+        DEFINE(KVM_VRMA_SLB_V, offsetof(struct kvm, arch.vrma_slb_v));
         DEFINE(VCPU_DSISR, offsetof(struct kvm_vcpu, arch.shregs.dsisr));
         DEFINE(VCPU_DAR, offsetof(struct kvm_vcpu, arch.shregs.dar));
 #endif
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 15c5a4f6de01..8bea12086b67 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -100,14 +100,14 @@ data_access_not_stab:
 END_MMU_FTR_SECTION_IFCLR(MMU_FTR_SLB)
 #endif
         EXCEPTION_PROLOG_PSERIES(PACA_EXGEN, data_access_common, EXC_STD,
-                                 KVMTEST_PR, 0x300)
+                                 KVMTEST, 0x300)
 
         . = 0x380
         .globl data_access_slb_pSeries
 data_access_slb_pSeries:
         HMT_MEDIUM
         SET_SCRATCH0(r13)
-        EXCEPTION_PROLOG_1(PACA_EXSLB, KVMTEST_PR, 0x380)
+        EXCEPTION_PROLOG_1(PACA_EXSLB, KVMTEST, 0x380)
         std     r3,PACA_EXSLB+EX_R3(r13)
         mfspr   r3,SPRN_DAR
 #ifdef __DISABLED__
@@ -329,8 +329,8 @@ do_stab_bolted_pSeries:
         EXCEPTION_PROLOG_PSERIES_1(.do_stab_bolted, EXC_STD)
 #endif /* CONFIG_POWER4_ONLY */
 
-        KVM_HANDLER_PR_SKIP(PACA_EXGEN, EXC_STD, 0x300)
-        KVM_HANDLER_PR_SKIP(PACA_EXSLB, EXC_STD, 0x380)
+        KVM_HANDLER_SKIP(PACA_EXGEN, EXC_STD, 0x300)
+        KVM_HANDLER_SKIP(PACA_EXSLB, EXC_STD, 0x380)
         KVM_HANDLER_PR(PACA_EXGEN, EXC_STD, 0x400)
         KVM_HANDLER_PR(PACA_EXSLB, EXC_STD, 0x480)
         KVM_HANDLER_PR(PACA_EXGEN, EXC_STD, 0x900)