KVM: PPC: Book3S HV: Framework and hcall stubs for nested virtualization

This starts the process of adding the code to support nested HV-style
virtualization.  It defines a new H_SET_PARTITION_TABLE hypercall which
a nested hypervisor can use to set the base address and size of a
partition table in its memory (analogous to the PTCR register).
On the host (level 0 hypervisor) side, the H_SET_PARTITION_TABLE
hypercall from the guest is handled by code that saves the virtual
PTCR value for the guest.

This also adds code for creating and destroying nested guests and for
reading the partition table entry for a nested guest from L1 memory.
Each nested guest has its own shadow LPID value, different in general
from the LPID value used by the nested hypervisor to refer to it.  The
shadow LPID value is allocated at nested guest creation time.

Nested hypervisor functionality is only available for a radix guest,
which therefore means a radix host on a POWER9 (or later) processor.

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

1 files changed, 33 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/kvm_book3s_64.h b/arch/powerpc/include/asm/kvm_book3s_64.h
index 5c0e2d9a7e15..6d67b6a9e784 100644
--- a/arch/powerpc/include/asm/kvm_book3s_64.h
+++ b/arch/powerpc/include/asm/kvm_book3s_64.h
@@ -23,6 +23,39 @@
 #include <linux/string.h>
 #include <asm/bitops.h>
 #include <asm/book3s/64/mmu-hash.h>
+#include <asm/cpu_has_feature.h>
+
+#ifdef CONFIG_PPC_PSERIES
+static inline bool kvmhv_on_pseries(void)
+{
+	return !cpu_has_feature(CPU_FTR_HVMODE);
+}
+#else
+static inline bool kvmhv_on_pseries(void)
+{
+	return false;
+}
+#endif
+
+/*
+ * Structure for a nested guest, that is, for a guest that is managed by
+ * one of our guests.
+ */
+struct kvm_nested_guest {
+	struct kvm *l1_host;		/* L1 VM that owns this nested guest */
+	int l1_lpid;			/* lpid L1 guest thinks this guest is */
+	int shadow_lpid;		/* real lpid of this nested guest */
+	pgd_t *shadow_pgtable;		/* our page table for this guest */
+	u64 l1_gr_to_hr;		/* L1's addr of part'n-scoped table */
+	u64 process_table;		/* process table entry for this guest */
+	long refcnt;			/* number of pointers to this struct */
+	struct mutex tlb_lock;		/* serialize page faults and tlbies */
+	struct kvm_nested_guest *next;
+};
+
+struct kvm_nested_guest *kvmhv_get_nested(struct kvm *kvm, int l1_lpid,
+					  bool create);
+void kvmhv_put_nested(struct kvm_nested_guest *gp);
 
 /* Power architecture requires HPT is at least 256kiB, at most 64TiB */
 #define PPC_MIN_HPT_ORDER	18