KVM: PPC: Keep a record of HV guest view of hashed page table entries

This adds an array that parallels the guest hashed page table (HPT),
that is, it has one entry per HPTE, used to store the guest's view
of the second doubleword of the corresponding HPTE.  The first
doubleword in the HPTE is the same as the guest's idea of it, so we
don't need to store a copy, but the second doubleword in the HPTE has
the real page number rather than the guest's logical page number.
This allows us to remove the back_translate() and reverse_xlate()
functions.

This "reverse mapping" array is vmalloc'd, meaning that to access it
in real mode we have to walk the kernel's page tables explicitly.
That is done by the new real_vmalloc_addr() function.  (In fact this
returns an address in the linear mapping, so the result is usable
both in real mode and in virtual mode.)

There are also some minor cleanups here: moving the definitions of
HPT_ORDER etc. to a header file and defining HPT_NPTE for HPT_NPTEG << 3.

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, 18 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/kvm_book3s_64.h b/arch/powerpc/include/asm/kvm_book3s_64.h
index 2054e4726ba2..fa3dc79af702 100644
--- a/arch/powerpc/include/asm/kvm_book3s_64.h
+++ b/arch/powerpc/include/asm/kvm_book3s_64.h
@@ -35,6 +35,14 @@ static inline void svcpu_put(struct kvmppc_book3s_shadow_vcpu *svcpu)
 
 #define SPAPR_TCE_SHIFT         12
 
+#ifdef CONFIG_KVM_BOOK3S_64_HV
+/* For now use fixed-size 16MB page table */
+#define HPT_ORDER       24
+#define HPT_NPTEG       (1ul << (HPT_ORDER - 7))        /* 128B per pteg */
+#define HPT_NPTE        (HPT_NPTEG << 3)                /* 8 PTEs per PTEG */
+#define HPT_HASH_MASK   (HPT_NPTEG - 1)
+#endif
+
 static inline unsigned long compute_tlbie_rb(unsigned long v, unsigned long r,
                                              unsigned long pte_index)
 {
diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 66c75cddaec6..629df2ed22f7 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -166,9 +166,19 @@ struct kvmppc_rma_info {
         atomic_t         use_count;
 };
 
+/*
+ * The reverse mapping array has one entry for each HPTE,
+ * which stores the guest's view of the second word of the HPTE
+ * (including the guest physical address of the mapping).
+ */
+struct revmap_entry {
+        unsigned long guest_rpte;
+};
+
 struct kvm_arch {
 #ifdef CONFIG_KVM_BOOK3S_64_HV
         unsigned long hpt_virt;
+        struct revmap_entry *revmap;
         unsigned long ram_npages;
         unsigned long ram_psize;
         unsigned long ram_porder;