KVM: MIPS/T&E: Expose CP0_EntryLo0/1 registers

Expose the CP0_EntryLo0 and CP0_EntryLo1 registers through the KVM
register access API. This is fairly straightforward for trap & emulate
since we don't support the RI and XI bits. For the sake of future
proofing (particularly for VZ) it is explicitly specified that the API
always exposes the 64-bit version of these registers (i.e. with the RI
and XI bits in bit positions 63 and 62 respectively), and they are
implemented in trap_emul.c rather than mips.c to allow them to be
implemented differently for VZ.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org

Documentation/virtual/kvm/api.txt

@@ -2061,6 +2061,8 @@ registers, find a list below:
   MIPS  | KVM_REG_MIPS_LO               | 64
   MIPS  | KVM_REG_MIPS_PC               | 64
   MIPS  | KVM_REG_MIPS_CP0_INDEX        | 32
+  MIPS  | KVM_REG_MIPS_CP0_ENTRYLO0     | 64
+  MIPS  | KVM_REG_MIPS_CP0_ENTRYLO1     | 64
   MIPS  | KVM_REG_MIPS_CP0_CONTEXT      | 64
   MIPS  | KVM_REG_MIPS_CP0_USERLOCAL    | 64
   MIPS  | KVM_REG_MIPS_CP0_PAGEMASK     | 32
@@ -2149,6 +2151,12 @@ patterns depending on whether they're 32-bit or 64-bit registers:
   0x7020 0000 0001 00 <reg:5> <sel:3>   (32-bit)
   0x7030 0000 0001 00 <reg:5> <sel:3>   (64-bit)
 
+Note: KVM_REG_MIPS_CP0_ENTRYLO0 and KVM_REG_MIPS_CP0_ENTRYLO1 are the MIPS64
+versions of the EntryLo registers regardless of the word size of the host
+hardware, host kernel, guest, and whether XPA is present in the guest, i.e.
+with the RI and XI bits (if they exist) in bits 63 and 62 respectively, and
+the PFNX field starting at bit 30.
+
 MIPS KVM control registers (see above) have the following id bit patterns:
   0x7030 0000 0002 <reg:16>
 

arch/mips/include/asm/kvm_host.h

@@ -352,7 +352,9 @@ struct kvm_vcpu_arch {
 #define kvm_read_c0_guest_index(cop0)		(cop0->reg[MIPS_CP0_TLB_INDEX][0])
 #define kvm_write_c0_guest_index(cop0, val)	(cop0->reg[MIPS_CP0_TLB_INDEX][0] = val)
 #define kvm_read_c0_guest_entrylo0(cop0)	(cop0->reg[MIPS_CP0_TLB_LO0][0])
+#define kvm_write_c0_guest_entrylo0(cop0, val)	(cop0->reg[MIPS_CP0_TLB_LO0][0] = (val))
 #define kvm_read_c0_guest_entrylo1(cop0)	(cop0->reg[MIPS_CP0_TLB_LO1][0])
+#define kvm_write_c0_guest_entrylo1(cop0, val)	(cop0->reg[MIPS_CP0_TLB_LO1][0] = (val))
 #define kvm_read_c0_guest_context(cop0)		(cop0->reg[MIPS_CP0_TLB_CONTEXT][0])
 #define kvm_write_c0_guest_context(cop0, val)	(cop0->reg[MIPS_CP0_TLB_CONTEXT][0] = (val))
 #define kvm_read_c0_guest_userlocal(cop0)	(cop0->reg[MIPS_CP0_TLB_CONTEXT][2])

arch/mips/kvm/trap_emul.c

@@ -646,6 +646,8 @@ static void kvm_trap_emul_flush_shadow_memslot(struct kvm *kvm,
 
 static u64 kvm_trap_emul_get_one_regs[] = {
 	KVM_REG_MIPS_CP0_INDEX,
+	KVM_REG_MIPS_CP0_ENTRYLO0,
+	KVM_REG_MIPS_CP0_ENTRYLO1,
 	KVM_REG_MIPS_CP0_CONTEXT,
 	KVM_REG_MIPS_CP0_USERLOCAL,
 	KVM_REG_MIPS_CP0_PAGEMASK,
@@ -706,6 +708,12 @@ static int kvm_trap_emul_get_one_reg(struct kvm_vcpu *vcpu,
 	case KVM_REG_MIPS_CP0_INDEX:
 		*v = (long)kvm_read_c0_guest_index(cop0);
 		break;
+	case KVM_REG_MIPS_CP0_ENTRYLO0:
+		*v = kvm_read_c0_guest_entrylo0(cop0);
+		break;
+	case KVM_REG_MIPS_CP0_ENTRYLO1:
+		*v = kvm_read_c0_guest_entrylo1(cop0);
+		break;
 	case KVM_REG_MIPS_CP0_CONTEXT:
 		*v = (long)kvm_read_c0_guest_context(cop0);
 		break;
@@ -817,6 +825,12 @@ static int kvm_trap_emul_set_one_reg(struct kvm_vcpu *vcpu,
 	case KVM_REG_MIPS_CP0_INDEX:
 		kvm_write_c0_guest_index(cop0, v);
 		break;
+	case KVM_REG_MIPS_CP0_ENTRYLO0:
+		kvm_write_c0_guest_entrylo0(cop0, v);
+		break;
+	case KVM_REG_MIPS_CP0_ENTRYLO1:
+		kvm_write_c0_guest_entrylo1(cop0, v);
+		break;
 	case KVM_REG_MIPS_CP0_CONTEXT:
 		kvm_write_c0_guest_context(cop0, v);
 		break;